College of Agriculture, Engineering and Science

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Alleviating delayed field curing-induced deterioration in rice seeds by cathodic water invigoration: a comparison of seed and seedling responses in two upland rice species and their interspecific hybrid.
(2021) Bam, Raphael Kwame.; Varghese, Boby.; Naidoo, Sershen.; Pammenter, Norman William.
Rice constitutes the major source of the world’s food supply. A number of varieties are grown in many parts of the world, all which produce orthodox seeds that are usually stored between growing seasons. As in other crop species, storage-induced loss of seed quality (viability and vigour) is inevitable but considerable research effort has been invested in optimising seed bank storage protocols for rice to ensure acceptably high levels of seed germinability and seedling emergence. However, poor post-harvest practices such as delayed field curing before threshing in developing countries in the humid tropics, such as Ghana, result in curing-induced seed deterioration in the field prior to ex situ storage. Given that many rice growing regions are likely to experience significant levels of climate change, seed processing and storage induced declines in rice seed quality could exacerbate the crop losses incurred by rice farmers in these regions in the future. This motivated the present study which was designed around three aims: 1) to investigate how environmental conditions and the duration of field curing influenced seed macro-structural integrity, susceptibility to microbial infection, and seed germinability and vigour; 2) to identify macro-structural and ultrastructural indicators/ biomarkers of field curing and associated storage-induced stress/ damage; 3) to assess whether the invigoration of field-cured seeds with cathodic water (CW), an established antioxidant-based seed invigoration medium, and deionized water (DW) can alleviate the deteriorative effects of delayed field curing on rice seed cellular integrity, germination and subsequent seedling growth and biomass. The specific objectives of this comparative study, which involved an Asian (Oryza sativa L.) and African (Oryza glaberrima Steud) upland rice species and their interspecific hybrid (O. sativa × O. glaberrima), were as follows: a) to compare the impacts of delayed field curing in wet and dry environments on seed physical, physiological and pathological quality; b) to identify potential ultrastructural biomarkers of seed sensitivity to delayed field curing-induced stress/ damage in embryonic root meristematic cells using transmission electron microscopy (TEM); c) to assess whether CW invigoration alleviates cellular stress/ damage induced by delayed field curing using selected ultrastructural biomarkers of seed sensitivity to such curing-induced stress/ damage; and d) to assess whether invigoration with CW and DW improves seed germinability and emergence, and subsequent plant growth in field cured seeds, relative to non-invigorated (NI) dry seeds.
Assessing the water productivity of sweet potato (Ipomoea batatas (L.) Lam.)
(2022) Mthembu, Thando Lwandile.; Kunz, Richard Peters.; Mabhaudhi, Tafadzwanashe.
In water-stressed countries like South Africa, the reliable quantification of actual crop evapotranspiration (ETA) and yield across a wide range of environments is important for improved agricultural water management. In addition, researchers are shifting their primary focus from well-studied major crops to neglected and underutilised crops. Orange-fleshed sweet potato (Ipomoea batatas (L). Lam.) remains an underutilised root and tuber crop (RTC) in South Africa, despite its potential as being nutrient-dense, high yielding and water use efficient, as reported in local literature. When compared to conventional crops, knowledge is limited on the water use and yield of RTCs under rainfed and precision agricultural production in South Africa. It is therefore important to further investigate whether the water use of orangefleshed sweet potato (OFSP) will hinder its production at the commercial scale. This study attempted to contribute towards the limited research on the crop water productivity (CWP) of OFSP. A rainfed field trial with optimum fertilisation was conducted at Fountainhill Estate (KwaZulu-Natal, South Africa) to estimate seasonal ETA, yield and CWP. The soil water balance method was used to determine ETA accumulated over the growing season from 14 December 2021 to 11 April 2022. Total ETA for OFSP was estimated at 468.13 mm, which was used to calculate fresh and dry CWP values of 7.45 and 2.59 kg m-3 , based on final fresh and dry tuber yields of 34.89 and 12.12 t ha-1 , respectively. Harvested tuber and above-ground biomass samples were sent to a laboratory to analyse nutrient content (NC). The nutritional water productivity (NWP) was determined as the product of CWP and NC, highlighting the potential of OFSP to alleviate malnutrition, especially if grown in rural communities. Field observations were used to partially calibrate the Soil Water Balance (SWB) and AquaCrop models. These models were used to simulate ETA, yield and biomass accumulation, from which CWP and NWP were calculated. Compared to observations, AquaCrop provided a better estimate of CWP (2.55 kg m-3 ) relative to the SWB model (1.16 kg m-3 ). However, AquaCrop simulated higher soil water content relative to measurements from volumetric soil water content sensors. This study showed that under suitable management practices, OFSP has the potential to be grown commercially, since the crop can produce high yields and nutrient contents under rainfed agricultural production. However, to improve production, future studies need to conduct research to improve tuber yield and biomass accumulation. Furthermore, the AquaCrop and SWB models should be calibrated and validated across different agroecological zones in South Africa.
Bioeconomic feasibility of aquaponics in South Africa: leapfrogging for sustainable development of freshwater aquaculture.
(2020) Adeleke, Babatunde Ayoade.; Robertson-Andersson, Deborah Vivienne.; Moodley, Ganas Kandasamy.; Taylor, Simone.
Food security is being threatened globally due to a combination of factors, such as climate change, anthropogenic pressures and burgeoning competition for limited water and land resources. The need to adopt environmentally and economically sound sustainable food production systems which are adaptable to the prevailing environmental stressors is imperative. Aquaponics sustainably converts aquaculture waste into nutrients for plant uptake resulting in an unconventional food production system which potentially provides an economically viable means of food production. Integrated recirculating aquaculture as adaptive technology is complex and capital intensive, thus, must be financially sustainable. This study, therefore, assessed the bioeconomic feasibility of aquaponics (a branch of aquaculture) in South Africa as a potential leapfrog technology for the rapid development of aquaculture, attainment of food security and local economic development. Quantitative and qualitative SWOT analyses, and key success factors of leading aquaculture players in Africa (Egypt, Nigeria and Uganda) were used as a benchmark to assess the South African aquaculture sector. Qualitative analysis of South African aquaculture sector vis-à-vis the leading aquaculture players in Africa reveals a suboptimal environment that is not suitable to drive costeffective and competitive conventional large-scale commercial aquaculture. Also, inadequate enabling environment due to bureaucratic hindrances towards the implementation of well-crafted aquaculture development policies and framework, and higher operating cost were identified. The quantitative SWOT analysis of key aquaculture players in Africa revealed Egypt was having the highest aquaculture development competitive strengths, and Nigeria showed the highest aquaculture development and market opportunities. Quantitative SWOT analysis of key aquaculture species in South Africa showed trout and tilapia have the highest competitive strengths, while abalone, oyster and marron crayfish showed good market opportunities but weak in competitive strengths. Growth performance of Oreochromis mossambicus and the yields from plants – tomato, pepper and cucumber due to the effects of plant density and stem pruning were assessed in a twin system designed, constructed and operationalized as a low-cost, small-scale aquaponic system. The economic viability of the aquaponic system was assessed using the price trend analysis of fresh produce in South Africa, biomass yield, cost inputs and revenue models using conventional aquaponic cultural methods. Financial performance was determined using financial metrics such as return on investment (ROI), net present value (NPV), internal rate of return (IRR) and profitability. Analyses were modelled to determine the financial performance of the aquaponic system. The growth performance and yield of fish cultured in the aquaponic system showed excellent performance based on FCR (1.25 %), survival rate (97.5 %), LWR r2 (0.945), regression coefficient b (3.1) and condition factor K (1.93). Total and marketable yield of vegetables (tomato, sweet pepper and cucumber) significantly increased (p < 0.05) with a higher plant density of 8 plants /m2 compared to 5 plants/m2. Plants with a higher stem pruning to two and three stems performed significantly better than those pruned to one stem (p < 0.05). The interactive effects of a higher plant density and stem pruning resulted in significant (p < 0.05) higher total and marketable yields with all the plants. Economic analysis of the small-scale aquaponic setup and operation did not present economic feasibility with the adoption of conventional cultural techniques (a revenue model of 59: Abstract 41 % fish to plant ratio) as a result of the higher operating cost associated with fish production. A fish to plant revenue model of 42 : 58 % ratio (achieved by adopting optimized cultural technique) however, showed marginal economic viability. Plant yield in aquaponics can be improved for higher economic returns through the synergistic optimization of plant density and stem pruning while adopting other optimal cultural management practices. A minimum revenue model of 30 : 70 % fish to plant ratio is recommended for aquaponic operations in South Africa to attain economic feasibility. Aquaponics thus presents optimistic potential to drive sustainable and feasible food production in South Africa with the adoption of viable production and marketing strategies.
Bone quality and incidence of urolithiasis in male broiler breeders fed a male or female ration.
(2024) Dube, Sithembisiwe.; Tyler, Nicola Claire.
Separate sex feeding is highly practiced in breeder farms as it gives a more targeted approach to nutrition, aligning the dietary requirements with the specific needs of male and female birds. Some breeder farmers give the female ration to male breeders as it saves having two feed silos per house and eliminates the chances of females receiving the wrong feed. However, the drawback is that the female ration contains high crude protein (CP), calcium (Ca), and phosphorous (P), which is more than recommended for male requirements. A total of 40 male broiler breeders fed a male-specific ration (MM), and 40 male broiler breeders fed a female ration (MF) at depletion were acquired from KwaZulu-Natal farms. Kidney weight (KW) and kidney lesion score (KLS) from euthanised male broiler breeders were examined as an indication of urolithiasis. Tibia bone weight (BW), bone thickness(BT), bone breaking strength (BBS), tibia ash% (TA%), organic matter (OM%) and Ca/P% were quantified to assess the effects of excess CP, Ca and P on bone quality. Data collected were subjected to a two-sample t-test at a 95% confidence interval using GenStat statistical analysis software, and principal component analysis (PCA) was performed using XLSTAT. The biplots from the PCA were used to predict correlation among the variables. The study results showed that the kidney weights of MF were significantly larger compared to MM (P<0.001). Kidney lesion scores were observed in 50% MF and were significantly higher than in MM (P<0.001). Significant differences in BW, BBS, TA%, and OM% were found between MM and MF. Bone thickness, and bone Ca%, P% and Ca/P% were not significantly different among the two groups. The findings suggested that high CP, Ca and P in female feed given to male broiler breeders can negatively affect kidney and bone quality. The results indicated a significant correlation between dietary composition, bone strength and the incidence of urolithiasis. The study concluded that the nutritional composition designed for female broiler breeders may not be entirely suitable for the physiological needs of male breeders, contributing to an increased susceptibility to urolithiasis. Also, high Ca can interfere with the absorption or retention of Ca and other minerals like P, resulting in low bone quality.
Breeding bambara groundnut (vigna subterranea (L.) verdc) for enhanced yield and nutritional quality in South Africa.
(2023) Majola, Nomathemba Gloria.; Shimelis, Hussein.; Gerrano, Abe Shegro.
Bambara groundnut (Vigna subterranea (L.) Verdc.; 2n= 2x = 22) is a nutrient-dense grain legume cultivated in sub-Saharan Africa (SSA) and Asia. The current food systems in tropical and subtropical regions depend on the cultivation and use of a few commodity crop species. This causes most indigenous crop species, such as Bambara groundnut, to remain neglected by researchers and underutilised in the value chains. Underutilised crop species have received limited research and development attention from researchers and policymakers, and hence, their economic value, production methods, seed enterprises, product development and commercialisation are not yet fully explored. Due to a lack of systematic genetic improvement, the yield of most underutilised crops is low (<0.85 ton ha-1) and stagnant. Unlocking Bambara groundnut’s economic and value-adding potential as an essential multipurpose food and cash crop will enhance food and nutritional security in developing countries. Research on Bambara groundnut in South Africa is relatively peripheral and there are no known improved varieties of this crop with high yield and nutritional quality. Therefore, specific objectives of this study were: (1) to document the progress made on Bambara groundnut production, utilisation and genetic improvement in SSA to discern the key production constraints, genetic resources and analysis, breeding methods and gains on yield and nutrition to guide breeding; (2) to assess them genotype-by-environment interaction (GEI) effect on grain yield and to select best adapted Bambara groundnut genotypes in South African target production areas for breeding; (3) to determine the compositions of phytochemicals and mineral elements present in Bambara groundnut genetic pool to identify superior and contrasting genotypes to guide product development and breeding; (4) to determine the magnitude of the genetic diversity and population structure of Bambara groundnut collections of South Africa using high throughput single nucleotide polymorphisms (SNP) markers to complement phenotypic and nutrition profile data for genotype selection and breeding; and (5) to determine the combining ability effects and gene action conditioning yield and related traits in Bambara groundnut genotypes to identify the best combiner donor parents and progenies for genetic advancement, cultivar development and release. The first part of the study reviewed progress on Bambara groundnut production, utilisation and genetic improvement in SSA. The study presented key production constraints, genetic resources and analysis, breeding methods and genetic gains on yield and nutritional quality. Modern crop management, production technologies, and value chains are yet to be developed in Africa to achieve economic gains from Bambara groundnut production and marketing. Improved crop management and post-harvest handling technologies, modern varieties with high yield and nutritional quality, value addition and market access are among the key considerations in current and future Bambara groundnut research and development programs. Information presented will guide sustainable production and effective crop breeding to pursue food and nutrition security and improved livelihoods through Bambara groundnut enterprises. In the second chapter of the study, 75 Bambara groundnut genotypes were evaluated across seven selected environments using a 5 x 15 alpha lattice design with three replications. The study revealed significant (p<0.05) differences among genotypes (G), environments (E) and GEI effects on grain yield. A high proportion of the observed variation was due to GEI (36.62%), followed by environment (35.63%) and genotype (24.16%) effects. Grain yield across environments ranged from 1.4 ton ha-1 for ARC Bamb-68 to 0.10 ton ha-1 for ARC Bamb-74. Genotype ARC Bamb-68 (0.96 ton ha-1), ARC Bamb-9 (0.88 ton ha-1) and ARC Bamb-54 (0.84 ton ha-1) attained the highest grain yield across locations, while ARC Bamb-74 exhibited the lowest grain yield of 0.16 ton ha-1. The genotype and genotype-by-environment biplot identified ARC Bamb-17, ARC Bamb-14, ARC Bamb-20, ARC Bamb-18, ARC Bamb-14, and ARC Bamb-26 as the most stable genotypes across locations, while ARC Bamb-18 and ARC Bamb-54 were specifically adapted to Loskop and Brits. The Mafikeng site was ideal for Bambara groundnut evaluation, genotype differentiation, and large-scale seed production. The selected genotypes with high grain yields and stability are valuable genetic resources as breeding parents for Bambara groundnut improvement in South Africa. In the third chapter of the study, 75 genetically diverse Bambara groundnut genotypes were field evaluated across four environments using a 15 x 5 alpha lattice design with three replications during the 2020-2021 cropping season. Genotypes were profiled for fat, phenolic and flavonoids contents at the Agricultural Research Council (ARC) analytical laboratory in South Africa. Further, the genotypes were assessed for the contents of the following minerals: calcium (Ca), iron (Fe), potassium (K), phosphorus (P), zinc (Zn) and nitrogen (N). The nutritional content of the test genotypes varied significantly (P<0.05), which were affected by the genotype and environment interactions. The Ca, Fe, K and Zn content varied from 150.70 to 216.53, 4.30 to 16.77, 771.99 to 1155.89 and 5.50 to 7.17 mg.100 g−1 dry seed sample, respectively. Genotypes, including ARC Bamb-2, ARC Bamb-19, ARC Bamb-73, ARC Bamb-56, ARC Bamb-37, ARC Bamb-3 and ARC Bamb-69 exhibited the highest fat content (>6.00 %). ARC Bamb-40 and ARC Bamb-59 recorded a higher mean Fe content of 16.00 mg.100 g−1. ARC Bamb-2 was the top-performing genotype with high fat content (6%), Ca (211.93 mg.100 g−1), and Zn (7.17 mg.100 g−1 ). Ca, K, and N contents displayed strong correlations (r>0.60, P<0.05). Phosphorus and Zn contents exhibited moderate correlations with Ca. Overall, the study selected genotypes ARC Bamb-73, ARC Bamb-19, ARC Bamb-9 and ARC Bamb-2 with high compositions of essential nutrients for product development or breeding. The selected genetic resources are valuable for trait integration and developing new breeding populations with enhanced nutrient compositions and agronomic and market-preferred traits. In the fourth part of the study, the magnitude of the genetic diversity and population structure of South Africa Bambara groundnut collections was determined using high throughput single nucleotide polymorphisms (SNP) markers. Ninety-three genotypes were genotyped with 2286 SNP markers and phenotyped with some unique complementary morpho-agronomic traits of the crop. The mean genetic diversity value was 0.32, revealing moderate genetic differences among the assessed genotypes. Cluster and structure analyses grouped the tested genotypes into two distinct categories. Further, the analysis of molecular variance partitioned the total genetic variation into among genotypes (90%), within genotypes (8%) and among populations (2%). The results revealed two heterotic groups for hybridisation and selection programs. The following unique genotypes were selected: ARC Bamb-37 (with spreading growth type), ARC Bamb-49 (bunch type), ARC Bamb-61 (semi-bunch) and ARC Bamb-83 (spreading) using the SNP markers and desirable agronomic traits. The study provided new insight on Bambara groundnut genetic profiles of South African collections, which will assist in conservation strategy and management of the crop for effective breeding. The final part of the study assessed combining ability effects and gene action conditioning yield and related traits in Bambara groundnut genotypes to identify the best combiner donor parents and progenies for genetic advancement and breeding. Ten contrasting parents were selected and crossedusing a 10 × 10 half-diallel mating design, and 45 progenies developed. The progenies and their parents were field evaluated using a 5 × 11 alpha lattice design with two replications in two contrasting locations in South Africa. Data was collected on agronomic traits and subjected to statistical analyses to compute genetic parameters. Genotype × location interaction effect was significant (P < 0.05) for the studied agronomic traits. General combining ability (GCA) and specific combining ability (SCA) effects were significant in most assessed agronomic traits, including yield per plant. The GCA × location and SCA × location interaction effects were significant for most traits. A Baker’s ratio of < 1 were recorded for most assessed traits, indicating the preponderance of non-additive gene effects conditioning the traits. The parental lines such as ARC Bamb-25, ARC Bamb-8 and ARC Bamb-55 recorded positive and desirable GCA effects for yield per plant. The progenies ARC25×ARC8, ARC44×ARC9 and ARC6×ARC9 had desirable SCA effects for yield per plant, ARC44×ARC8, ARC44×ARC68, ARC42×ARC8 for higher number of secondary branches per stem, ARC25 ×ARC8 for early maturity, ARC42×ARC55 for higher number of pods per plant and ARC42 ×ARC57 for increased seed width. The new families selected in the current study are useful breeding populations and will be subjected to selection and multilocation evaluation to release the best-performing varieties. Overall, the present study appraised the present production constraints, genetic resources and analysis, breeding methods and genetic gains on yield and nutritional quality to guide future breeding. Moreover, new Bambara groundnut breeding populations were developed with enhanced yield and nutritional compositions for genetic advancement and multilocation selection for variety release and adoption in South Africa.
Cathodic water invigoration of deteriorated orthodox seeds – implications on subsequent plant growth.
(2020) Fatokun, Kayode.; Beckett, Pichard Peter.; Varghese, Boby.; Pammenter, Norman William.
Orthodox seeds deteriorate even when kept under the best of conditions leading to loss of germination, poor seedling growth. In this study, a novel approach via the use of cathodic water, an electrolysed form of calcium magnesium solution, was used to invigorate fresh and controlled deteriorated seeds of wild (Bolusanthus speciosus (Bolus) Harms, Combretum erythrophyllum (Burch.) Sond., Erythrina caffra Thumb.) and agricultural (Pisum sativum L., Cucurbita pepo L.) species. Other treatment solutions investigated alongside cathodic water were un-electrolysed calcium-magnesium solution and deionized water. Fresh seeds of the test species were controlled deteriorated to 50% germination (P50) at 40°C and 100% relative humidity. Thereafter, the seeds were invigorated with the treatment solutions. Fresh and un-primed controlled deteriorated seeds served as the control. In addition, to study the mechanism of invigoration, the effects of priming on the membrane stability index (MSI), amylase activities, lipid peroxidation products malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) were investigated. The effects of priming on the reactive oxygen species (ROS) scavenging enzymes superoxide dismutase, and catalase and DNA (concentration and purity). All priming treatments improved germination, emergence, growth parameters and subsequent seedling photosynthesis relative to the unprimed seeds. In general, cathodic water was most effective at invigorating seeds in the all test species. Also, controlled deteriorated seeds benefitted more than the fresh seeds treatments. Analyses of the lipid peroxidation products and antioxidant enzyme activities in invigorated seeds provided support for the hypothesis that the effectiveness of cathodic water in the invigoration of debilitated orthodox seeds derive from its ability to act as a potent antioxidant. This study, which is a novel approach at bringing the concept of electrochemistry into germplasm conservation via the use of cathodic water, has also confirmed the efficacy of cathodic water in invigorating debilitated seeds. This is especially critical for seeds containing traits that may be under the threat of being lost due to various reasons. The current study reinforces the strong potential of cathodic water in the recovery of aged germplasm and improved yield of orthodox seeded species.
Designing T-cell epitope-based vaccine against Eimeria infection in chicken using immunoinformatics approach.
(2021) Madlala, Thabile.; Adeleke, Matthew Adekunle.; Okpeku, Moses.
Chicken coccidiosis is the most significant ubiquitous, intestinal parasitic disease known to infect chickens globally. It is recognised for incurring significant production loss to the poultry industry, caused by single or multiple Eimeria spp. infections which threaten chicken welfare and productivity. The emergence of drug resistance in parasites and pathogenicity reversion has put pressure on the poultry industry to reduce chemoprophylactic drugs and live vaccines as preventive measures against coccidiosis. Recombinant DNA vaccines have shown promising results as an alternative option, but complete protection has not been reported highlighting the need for the design of new vaccine against this disease. In this study, Eimeria antigens Immune Mapped Protein-1(IMP1) and Microneme Protein-2(MIC2) were explored using reverse vaccinology and immunoinformatics tool to predict and design potential multiepitope vaccine candidate against coccidiosis. A total of 28 and 19 antigenic T-cell epitopes were predicted and used to construct two multiepitope vaccines with 610 and 512 amino acids for IMP1 and MIC2, respectively. The produced vaccines exhibited favoured characteristics for an ideal vaccine candidate; they were antigenic (Vaxijen score of 0.5989 and 0.5103), immunogenic (scores: 10.15 and 9 419), thermostable (instability index <40 ), and non-allergic. The presence of IFN-gamma and IL-4 inducing epitopes in the constructed vaccine enables vaccine to trigger a cellular and humoral response within the host. Molecular docking of designed vaccines with toll-like receptors (TLR4 and TLR5) to determine vaccine interaction and stability was confirmed by molecular dynamics simulation root-mean square deviation (RMDS) and root-mean-square fluctuation (RMSF) analysis. The designed vaccines induced immune response through production of cytokines and antibodies associated with tertiary response. When exposed to online immune simulation C-ImmSim, both vaccines produced potent immune response through production of IgG, Tc and Th cell and memory Bcells. The constructed multiepitope vaccine in this present study is highly promising and as such further experimental work should be done to confirm its suitability against chicken coccidiosis.
Diversity of Eimeria tenella apical membrane antigen-1 from chickens in Mpumalanga province and its in silico epitope prediction as a vaccine candidate.
(2021) Tenza, Petronella Nokukhanya.; Adeleke, Matthew Adekunle.; Fatoba, Abiodun Joseph.
Coccidiosis has been a significant challenge in the poultry industry. There is a high request for the modification of a cost-effective immunizing agent to curtail this disease. Apical membrane antigen 1 (AMA1) has been reported as a protective antigen in sub-unit vaccine development against several apicomplexan parasites such as Plasmodium falciparum, Eimeria tenella and Eimeria maxima. However, knowledge of genetic diversity in this vaccine candidate is imperative. Also, to minimize the cost and time involved in producing a vaccine, computational vaccine design has received much attention through the immunoinformatics method. Therefore, screening for the potential vaccine epitopes in AMA1 that can induce cellular and humoral immune response through the immunoinformatics technique looks promising. This investigation aimed to detect the level of genetic diversity amid Eimeria tenella Apical Membrane Antigen 1(EtAMA1) in selected farms in Mpumalanga province and predict vaccine epitopes from this antigen. Four hundred fresh faecal samples were collected from 10 selected broiler chicken farms in Mpumalanga. The samples were screened for Eimeria oocyst using a compound microscope, and samples containing oocyst were further screened for E. tenella using molecular methods. AMA1 (n=103) was amplified from positive samples for E. tenella, and resulted amplicons were sent to Inqaba Biotec for sequencing and analyzed using MEGA6.06 and DnaSP programs. The results revealed low levels of genetic diversity among Mpumalanga EtAMA1 sequences which were measured by nucleotide diversity (0.0007) diversity, haplotype diversity (0.113) and haplotype number (3). Correspondingly, the haplotype network revealed 4 haplotypes, 3 of which consist of samples from Mpumalanga. Identification of immunogenic B- and T-cell epitopes from EtAMA1 sequences was further carried out and were used to construct a multiepitope vaccine (MEV) using immunoinformatics approaches. The constructed MEV is 311 amino acids long. It was constructed by linking 6 B-cell, 3 CD8+ epitopes and 6 CD4+ epitopes with appropriate adjuvant and linkers. Both adjuvant and linkers were used to increase the immunogenicity of the MEV. The designed MEV was highly antigenic and non-allergenic. The results showed a strong binding affinity of MEV with TLR4. These results suggest that the predicted vaccine could be a significant vaccine candidate against chicken coccidiosis through further experimental validation is still necessary.
Exploring the youth-agriculture nexus: implications on household food security and livelihoods.
(2023) Mukwedeya, Bright Takudzwa.; Mudhara, Maxwell.
The youth-agriculture nexus in Africa is critical to food and nutrition security, employment and livelihoods at multiple scales through multiple pathways. The Zimbabwean government, like several other African governments enacted policies and interventions to harness this opportunity. Despite the government's efforts, getting youth attracted or interested in agriculture has been a challenge while success has been elusive. The information gaps characterising most of Africa's policy environment are contributing to the failure of most youth policies and interventions. Robust and compelling evidence on the intersection of youth and agriculture is lacking. It is against this background that the study explores the youth-agriculture nexus and its implications on household food security and livelihoods. The study's specific objectives include determining the factors affecting rural youth participation in agriculture; examining the factors influencing migration willingness and choice of destination; determining the factors affecting life satisfaction and lastly; examining the factors influencing livelihood choice and food security among youth. The study examines the youth-agriculture intersection from various disciplines, considering noncognitive, demographic, social and economic factors. This is because of the complex and multi-dimensional nature of the youth-agriculture nexus. A pre-tested structured questionnaire collected data from 200 youths across three districts of Mashonaland East Province in Zimbabwe. Various econometric techniques of discrete choice and descriptive statistics analysed the data. The rights to anonymity, informed consent, and confidentiality were upheld to make the study ethical. The descriptive statistics show that most of the youth were males, household heads, unemployed, married, looking for a job and have a secondary level of education. Also, the results show that most of the youth in the study were food insecure, dissatisfied with their lives and willing to engage in migration. The study sheds light on the importance of noncognitive factors (expectancy and subjective task value) in understanding the youth-agriculture nexus. The results reveal that expectancy, utility and intrinsic value and cost statistically significantly influences youth career decisions and life outcomes. It follows that youth with expectancy, intrinsic or utility value engage and spent more hours in agriculture. Further, youth with utility or intrinsic value have high life satisfaction compared to their counterparts without utility or intrinsic value. The study also reveals that traditional factors such as age, marital status, level of education, access to land, household size and employment status statistically significantly influence youth career decisions and life outcomes. The study concludes that both noncognitive and traditional factors are critical in understanding youth career decisions and life outcomes and combined can provide a holistic and better understanding of the youth-agriculture nexus. In line with the literature, the future of agriculture and food security in rural Zimbabwe is uncertain. The results reveal that most of the youth are leaving or losing interest in agriculture. In the study, over 70 percent of the youth expressed low interest in engaging in the sector in the coming years. Second, a relatively high number of youths were willing to migrate. The results show that 69 percent of the youth in the study were willing to engage in migration. Last, low life satisfaction was a general characteristic among the youth. Over 60 percent of the youth in the study expressed dissatisfaction with their lives. Further, the study reveals a shift in some youth narratives in agriculture. First, a significant number of youths in the study opted for non-agricultural livelihoods over agriculture. Second, international migration has accelerated in rural Zimbabwe. Thus, rural migration is no longer limited to internal migration as many youths opted to engage in international migration. With a shift in youth narratives and uncertainty in agriculture and food insecurity in rural Zimbabwe, the study recommends the integration of noncognitive factors in policy decisions. Further, the study suggests the adoption of an interdisciplinary approach to the design of youth policies and interventions in agriculture. Also, the study recommends the need to set up multi-stakeholder platforms in policy decisions, planning and investment. Last, policy priority should focus on closing the large disparities between urban and rural Zimbabwe in terms of social services such as education, credit and communication.
Genetic characterization of citron watermelon (citrullus lanatus var. citroides [L.H. Bailey] mansf. ex greb.) and development of experimental hybrids.
(2023) Ngwepe, Mantlo Richard.; Shimelis, Hussein.; Mashilo, Jacob.
Citron watermelon (Citrullus lanatus var. citroides [L.H. Bailey] Mansf. ex Greb.) is indigenous to sub-Saharan Africa (SSA) with multiple uses, including human food and animal feed. Its succulent leaves are used as leafy vegetables, while the ripened yellow and orange-fleshed fruits are used to prepare various traditional dishes, and the seeds are roasted and consumed as snack. It is an emerging potential rootstock for producing grafted sweet watermelon (Citrulus lanatus var. lanatus) to improve fruit yield and biotic and abiotic stress tolerance. It is also a source of novel genes for breeding in sweet watermelon to improve fruit yield, quality and disease resistance. Citron watermelon in SSA is mainly cultivated using unimproved landrace varieties. Landraces exhibit marked phenotypic variation for fruit shape, size, skin colour patterns, and seed coat colours. Phenotypic and genetic variation among South African citron watermelon landraces is yet to be systematically assessed for diverse use and cultivar design. The overall goal of this study was to initiate a pre-breeding program for citron watermelon through identification and selection of unique and complementary genotypes for production, value-adding and breeding. The specific objectives of this study were: i. To determine the extent of genetic diversity among South African citron watermelon landrace accessions using selected simple sequence repeat (SSR) markers to identify genetically divergent accessions for trait integration and variety development; ii. To assess the phenotypic diversity of citron watermelon landrace accessions of South Africa and to select desirable genotypes with suitable agronomic and horticultural traits for direct production, breeding and conservation; iii. To estimate variance components, heritability and genetic advance of phenotypic traits in citron watermelon to guide the selection of superior genotypes for direct production and breeding; iv. To determine the combining ability and hybrid performance of citron watermelon genotypes for agronomic traits for breeding. In the first study, 48 citron watermelon landrace collections widely grown in the Limpopo Province of South Africa were genotyped using 11 selected SSR markers. The SSR markers amplified a total of 24 alleles, with a mean expected heterozygosity value of 0.38, indicating moderate genetic diversity among the studied accessions. Analysis of molecular variance attributed 8%, 75%, and 17% of the molecular variation between populations, among accessions and within accessions, respectively. Three distinctive genetic groups were identified based on cluster analysis. The following distantly related genotypes are recommended as breeding parents namely: WWM03, WWM04, WWM15, WWM16, WWM18, WWM22, WWM23, WWM24, WWM25, WWM26, WWM28, WWM33, WWM34, WWM35, WWM38, WWM39, WWM41, WWM66, WWM76, WWM78, WWM81, WWM84, WWM86 and WWM89 (selections from Cluster I), WWM14, WWM37, WWM42, WWM44, WWM46, WWM50, WWM65, WWM79, WWM85 and WWM87 (Cluster II), and WWM38, WWM47 and WWM48 (Cluster III). These are useful parental lines for pre-breeding to develop and release new varieties with multiple uses. In the second study, 36 selected citron watermelon landrace accessions were evaluated under field conditions across two environments using a 6 × 6 lattice design with three replicates. Data on key qualitative and quantitative traits were collected and subjected to non-parametric and parametric statistical analyses. The accessions showed wide phenotypic variation and unique traits for genetic improvement. Positive and significant correlations (p < 0.001) were recorded between total fruit yield per plant with plant height (r = 0.64), number of harvestable fruits (r = 0.70), number of marketable fruits (r = 0.73) and marketable fruit yield (r = 0.96). Seed yield per plant positively and significantly (p < 0.001) correlated with number of male flowers (r =0.68), plant height (r = 0.61) and total fruit yield (r = 0.79). Principal component analysis identified nine components which accounted for 86.38% of total variation amongst accessions for assessed phenotypic traits. The study recommended citron watermelon accessions such as WWM14, WWM16, WWM39, WWM41, WWM67 and WWM79 for use as leafy vegetables owing to their profuse branching ability and longer vine production. Whereas accessions including WWM03, WWM17, WWM35, WWM40, WWM50, WWM67, WWM79 and WWM85 are selected with larger fruit size. Accessions WWM05 and WWM09 are sour-flesh types which are suitable genetic stocks for breeding sweet-and-sour and sweet dessert watermelons. Orange-fleshed accessions such as WWM03, WWM04, WWM46, WWM64, WWM66 and WWM67 are recommended for fresh consumption, cooking, processing or variety design. Accessions WWM02, WWM03, WWM08, WWM14, WWM16, WWM23, WWM38, WWM40, WWM41 and WWM67 have red and white seed coat colour which are superior selections to prepare roasted citron watermelon seed snack. In the third study, variance components, heritability and genetic gains of phenotypic traits were estimated involving 36 accessions of citron watermelon grown under field conditions across two test environments using a 6 × 6 lattice design with three replicates. High broad-sense heritability and genetic advance as percent of the mean were recorded for fruit length at 83.86 and 4730.45%, seed length (77.73 and 1731.27%), hundred seed weight (73.73 and 4027.36%), fruit diameter (70.44 and 2949.64%) and fruit weight (70.39 and 8490.05%), respectively. Step-wise regression analysis revealed marketable fruit yield and total number of fruits per plant explaining 89% (R2 = 0.89) of total variation for total fruit yield per plant, whereas number of seed per fruit and hundred seed weight explained 92 (R2 = 0.92) of total variation for seed yield per fruit. Citron watermelon landrace accessions WWM03, WWM14, WWM16, WWM39, WWM65, WWM67 and WWM79 with high total fruit yield and seed yield per fruit were selected for production or breeding programme. In the fourth study, five selected parental genotypes were crossed in a 5 × 5 half-diallel mating design to develop 10 hybrids. The 15 families (five parents and 10 F1 hybrids) were evaluated across two environments using a randomized complete block design (RCBD) with three replications. General combining ability (GCA) and specific combining ability (SCA) effects were significant (p < 0.001) for most traits. Environment × GCA was non-significant, whereas Environment × SCA effects were significant (p < 0.001) for most traits. The ratios of GCA/SCA variances were less than unity for most traits, indicating non-additive gene action of the traits. Broad-sense heritability varied from low to moderate, implying variable selection response of the assessed traits among the F1 hybrids. The parental genotypes WWM16 with positive GCA effects for fruit and seed yield and WWM66, with positive GCA effects for the number of seeds per fruit and seed yield, were identified for hybrid breeding. The following F1 hybrids, namely: WWM04 × WWM16, WWM03 × WWM66 and WWM16 × WWM50 with positive SCA effects on total fruit yield per plant and marketable fruit yield per plant, and WWM04 × WWM50, WWM03 × WWM16 and WWM03 × WWM66 with positive SCA effects for number of seeds per fruit and total seed yield were identified. The study identified novel and best-performing F1 hybrids of citron watermelon for economic traits and are recommended for multi-environmental evaluations, variety registration and commercialization. Overall, the study revealed genetic and phenotypic variation in citron watermelon to select and recommend suitable genotypes for production and for breeding new generation varieties based on market needs and consumer preferences. The study recommends accessions such as WWM14, WWM16, WWM39, WWM64, WWM67, WWM76 and WWM79 with high fruit yield, and WWM03, WWM04, WWM14, WWM15, WWM16, WWM24, WWM28, WWM37, WWM46, WWM66 and WWM68 exhibiting high fruit and seed yield for breeding or direct production. The parents WWM04, WWM03 and WWM16 were identified as good combiners for fruit or seed yield and related-component traits for future breeding. The F1 hybrids derived from these parents, including WWM04 × WWM16, WWM03 × WWM16, WWM03 × WWM66, WWM16 × WWM50, and WWM04 × WWM50 were best performing for economic traits and new breeding population development.
Optimization of antifungal production by Bacillus species in the presence of nanoparticle supplementation and preliminary scale-up.
(2023) Nzimande, Sikhulile Nosimo.; Gueguim Kana, Evariste Bosco.; Ramchuran, Santosh Omrajah.; Sanusi, Adeyemi Isaac.
The intensive agricultural practices used to meet global crop production demands have resulted in the rigorous use of chemical pesticides. These ultimately compromise crop production as well as the environment. In order to alleviate this, cheaper and environmentally friendly, biocontrol agents have been considered as an alternative to chemical pesticides. Biosurfactants are a promising alternative to chemical pesticides due to their higher biodegradability, lower toxicity, and environmental friendliness. Amongst the many bacterial and fungal biosurfactant producers, biosurfactants from Bacillus species show promise as biocontrol agents. These biosurfactants are known for their wide biotechnological use in agricultural, industrial, and medicinal fields. However, large scale production is still faced with challenges such as low yields and high production cost thus raising the need for modelling, optimization, catalytic and scale up investigations. Hence, a study was undertaken with the aim of enhancing biosurfactant production through process modelling and optimization with subsequent assessment of the scale up potential of the optimized process. A Response Surface Methodology (RSM) using box Behnken design was used to investigate the optimal process conditions for improved biosurfactant production from B. subtilis BS20. The investigated process parameters included glucose concentration (10 – 30 g/L), incubation temperature (25 – 45℃) and incubation time (24 – 96 h). The developed model gave a high coefficient of determination (R2 ) = 0.86, p-value of 0.0279 and F-value of 4.62 for the modelled biosurfactant production. Optimized process conditions of 11.5 g/L glucose concentration, 24 h incubation time and 41o C for incubation temperature were obtained and produced a maximal antifungal activity of 68 mm. Moreover, supplementary inclusion of seven (7) different nanoparticles as a biocatalyst in the cultivation of B. subtilis BS20 was carried out using the optimal process condition to further improve antifungal (biosurfactant) production. The inclusion of nanoparticles favored increased biomass yield, but biosurfactant with high antifungal activity was not obtained. Moreover, when it comes to commercializing new bioprocess and bioproduct developments, bio – process scale-up in the biotechnology industry is an essential stage. This study therefore evaluated the scale up of biosurfactant production based on constant power consumption, Reynold number and impeller tip speed. The stirrer speed (n), impeller diameter (di), number of impellers (N), power number (Np), broth density (⍴), working volume and geometric factor (fc) were correlated with impeller tip speed (Vtip), Reynolds number (𝑅𝑅𝑅𝑅) and power consumption rate (P/V) to obtain the most suitable criterion for biosurfactant production in a 10 L bioreactor. Implementing constant Vtip value from the 1 L scale: 93 rpm, Reynold number (Re) 5.9E - 04, Power (P) 0.32 W, Power to Volume ratio (P/VL) 160 W/m3 , circulation time (tc) 5.2 s and shear stress (γ) 15.5 S-1, at 41 °C, gave the highest antifungal activity of 65 mm zone of inhibition in the 10 L scale bioreactor. The antifungal activity obtained for constant Vtip were comparable to those obtained at 1L bioreactors (57 mm), this showed that the bioprocess dynamics for achieving high antifungal activity are available, further paving the way for feasible commercialization strategies. This study has elucidated the optimum process conditions for B. subtilis BS20 metabolism for improved biosurfactant production resulting in significant antifungal activity. Furthermore, findings showed that the inclusion of nanoparticles biocatalyst to the process enhanced biomass yields. Process scale up provided preliminary data for large scale production of biosurfactant production from B. subtilis BS20.
Perceptions, willingness, opportunities, and effects of youth participation in agricultural enterprises.
(2023) Giwu, Ongama.; Mdoda, Lelethu.
Agriculture is a pivotal driver of South Africa's economic growth and development, necessitating active participation from the youth to ensure sustainability. Notwithstanding, agricultural production is significantly impacted by adverse climatic conditions, a shortage of labor, and inadequate market access, posing a substantial threat to current and future food security. To mitigate these challenges, imperative enhancements are required within the smallholder farming sector. Addressing these issues will be pivotal for ensuring a resilient and sustainable agricultural system. The integration of youth into agricultural enterprises is very important for the sector's development and improvement due to qualities such as high energy level, ability to use innovative technology, openness to new developmental ideas, and fast thinking. Despite being a critical resource, most of the youth is losing interest, migrating to agriculture and the is low involvement of young people in agriculture which raises concerns about the industry's future. This has resulted in a loss of the most important segment for production and innovation adoption of agriculture which will affect the agricultural output and food security components. This research study seeks to investigate the perceptions, willingness, opportunities, and effects of youth participation in agricultural enterprise factors, focusing on the Umzimvubu Local Municipality in the Eastern Cape province. The study sought to achieve the following specific objectives: (i) profiling the characteristics and involvement of youth in agricultural enterprise, (ii) investigating the nature of youth perceptions and their influence on youth’s aspiration to engage in agricultural enterprises, (iii) assessing challenges and opportunities for youth participating in agricultural enterprises, (iv) determination of factors influencing the willingness and interest of youth participation in agricultural enterprises, (v) determination of the contribution and effects of youth engaged in agricultural enterprise on employment creation and poverty alleviation. The research methodology that was used in the reasons for the phenomenon. The population of interest for this study was drawn from Umzimvubu Local Municipality in the Eastern Cape Province of South Africa. Judgemental sampling was employed to survey 210 youth aged 19-35 years using structured questionnaires, and various statistical analyses, including descriptive statistics, Perception and Aspiration Indices, Binary Logistic Regression, and Propensity Score Matching, were conducted. The findings reveal that youth display moderate perceptions regarding agriculture's potential to improve living standards, resulting in generally low aspirations and poor overall perceptions of the industry. Challenges faced by youth in agriculture include poor markets, access to technical assistance, access to mentors, lack of financial support, lack of information on inputs, vi pricing, water scarcity, and insufficient land. Empirical results revealed that household income, size, education, marital status, and perceptions were the main factors influencing youth participation in agricultural enterprises. Propensity Score Matching indicates a positive impact of youth participation on income, suggesting a potential to boost household income and alleviate poverty. The study recommends that policymakers allocate resources strategically and adopt innovative approaches to enhance youth participation in agriculture. The government should prioritize skills development and capacity-building among youth, introducing them to profitable agricultural enterprises that promote decent work practices through trainings. Various strategies, including provision of free or subsidized inputs, market facilitation, technical assistance, and business knowledge, are proposed. Moreover, involving youth in policy and program planning is advocated for a holistic and inclusive approach to sustainable agricultural development.
Physiological and biochemical investigations into the reinvigoration of deteriorated Brassica oleracea L. (Cabbage) and Lactuca sativa L. (Lettuce) seeds with antioxidants and inorganic salt solutions.
(2021) Adetunji, Ademola Emmanuel.; Varghese, Boby.; Naidoo, Sershen.; Pammenter, Norman William.
This study focused on reinvigorating deteriorated Brassica oleracea L. (cabbage) and Lactuca sativa L. (lettuce) seeds with antioxidants and inorganic (electrolysed and non-electrolysed) salt solutions. All pre-treatment solutions were applied to fresh (control) and controlled deteriorated (CDd) seeds at 75% viability (P75), 50% viability (P50) and 25% viability (P25). The pre-hydration treatments were compared in terms of their effects on seed germination, seedling vigour, electrolyte conductivity (EC), accumulation of lipid peroxidation products, protein carbonylation (PC), antioxidant enzymes and germination enzymes. The study also investigated the effects of invigorating CDd seeds with selected antioxidants on subsequent seedling growth, gas exchange and photochemistry under greenhouse conditions. Controlled deterioration, in general, resulted in the loss of seed vigour and viability but at higher rates in lettuce than cabbage, and increased EC and PC, and lowered antioxidant and germination enzymes activities in both species. However, significant lipid peroxidation was only recorded in lettuce seeds. Antioxidant pre-treatments enhanced viability of CDd seeds of cabbage at P25 and lettuce at P50 and P25, and improved seedling vigour of fresh, P75 and P50 cabbage, and P50 and P25 lettuce seeds. Antioxidant pretreatments reduced EC and lipid peroxidation in lettuce seeds, while PC was reduced in both species. The treatments also elevated antioxidant and germination enzymes activities in P25 cabbage seeds and P50 and P25 lettuce seeds. The inorganic salt pre-treatments did not enhance percentage seedling production in CDd cabbage seeds. However, in CDd lettuce seeds, Cacontaining solutions and electolysed (cathodic water) treatments promoted percentage normal seedling production and enhanced seedling vigour irrespective of pre-treatment solution pH or seed deterioration level. In the greenhouse studies, certain antioxidants promoted seedling vigour and leaf area in both species and enhanced shoot dry weight and gas exchange in lettuce. In summary, CDd lettuce seeds responded better to both types of invigoration (i.e., antioxidants and inorganic salt solutions) than cabbage seeds, while antioxidants appeared to be relatively more beneficial than inorganic salts in both species. The results suggest that the benefits of certain pre-treatment solutions were based on the enhancement of the activities of key antioxidant and germination enzymes, and the efficiency of photosynthesis at the early stages of growth. The results argue for the use of these seed pre-hydration treatments for mitigating poor stand establishment brought about by seed ageing, and as a useful approach to reinvigorating seeds in long-term storage collections for ensuring global food security.
Pre-breeding of okra (abelmoschus esculentus [L.] moench) for drought tolerance.
(2023) Mkhabela, Sonto Silindile.; Shimelis, Hussein.; Gerrano, Abe Shengro.
Okra (Abelmoschus esculentus [L.] Moench; 2n = 2x = 130) is an important vegetable and oil crop. It is extensively grown in tropical and subtropical regions with limited and erratic rainfall conditions. A lack of improved cultivars with drought tolerance hinders the production of okra in sub-Saharan Africa (SSA). Considerable phenotypic and genotypic variation present in okra genetic resources from SSA useful for cultivar design with enhanced fresh pod and oil yields and drought tolerance. However, the genetic diversity in SSA’s okra germplasm collection is yet to be explored for breeding targeting economic and horticultural traits. There has been limited progress in the breeding of okra for drought tolerance. Therefore, the specific objectives of this study were i) to determine the response of selected okra genotypes to drought stress using fresh fruit yield and yield-related traits to identify and select candidate genotypes for drought tolerance breeding, ii) to determine genetic diversity present among okra accessions using simple sequence repeats (SSR) and complementary phenotypic markers and to select genetically divergent and superior parental accessions for pre-breeding, iii) to assess the levels of drought tolerance in preliminarily selected okra accessions based on leaf gas exchange and chlorophyll fluorescence to determine best-performing genotypes for drought-tolerance breeding and iv) to determine the combining ability and heterosis of selected okra accessions for yield and yield-related traits to identify superior parents and progenies for breeding. The first part of the study involved 26 okra genotypes that were evaluated in glasshouse and field environments under drought-stressed (DS) and non-stressed (NS) conditions using a 13 × 2 alpha lattice design with two replications. The findings revealed significant (P < 0.05) genotype x testing environment x water condition interaction effects for most traits, allowing for the selection of okra genotypes suited for drier conditions. Yield per plant (YPP) positively and significantly correlated with fresh pod length (FPL) (r = 0.66; P ≤ 0.001), dry pod weight (DPW) (r = 0.80; P ≤ 0.001) and number of pods per plant (NPP) (r = 0.58; P ≤ 0.001) under DS condition in the field environment. The study identified genotypes with high yield and other desirable phenotypic attributes, which are useful genetic resources for future crosses and the selection of promising progenies based on combining abilities analyses and heritability under water-limited environments. In the second study, 26 preliminarily selected okra accessions were assessed using nine highly polymorphic SSR markers and phenotyped under DS and NS environmental conditions using a 13 × 2 alpha lattice design with two replications. The SSR markers revealed a mean heterozygosity value of 0.54, indicating moderate genetic diversity among the tested okra accessions. Cluster analysis based on phenotypic and SSR markers differentiated the accessions into three distinct genetic groups. Pod yield per plant (PYPP) was positively and significantly correlated with fresh pod length (FPL) (r = 0.81), above-ground biomass (ABG) (r = 0.69), and harvest index (HI) (r = 0.67) under DS conditions, and FPL (r = 0.83) and AGB (r = 0.60) under NS conditions. Genetically complementary accessions such as LS04, LS05, LS06, LS07, LS08, LS10, LS11, LS15, LS18, LS23, LS24, and LS26 were identified for their high yield potential and related yield-improving traits under DS conditions. The identified accessions were recommended as parents for hybridization and selection programs to improve the yield potential of okra under drought-stressed environments. In the third part of the study, 26 genetically diverse okra accessions were screened for physiological traits response under NS and DS conditions in a controlled glasshouse environment using a 13 × 2 alpha lattice design and three replications in two growing seasons. Statistical analyses revealed a significant genotype × water condition interaction effect for transpiration rate (T), net CO2 assimilation (A), intrinsic water use efficiency (WUEi), instantaneous water use efficiency (WUEins), minimum fluorescence (Fo′), maximum fluorescence (Fm′), maximum quantum efficiency of photosystem II photochemistry (Fv′/Fm′), the effective quantum efficiency of PSII photochemistry (ɸPSII), photochemical quenching (qP), nonphotochemical quenching (qN) and relative measure of electron transport to oxygen molecules (ETR/A). The results suggested variable drought tolerance of the studied okra accessions for selection. Seven principal components (PCs) contributing to 82% of the total variation for assessed physiological traits were identified under DS conditions. Leaf gas exchange parameters, T, A and WUEi, and chlorophyll fluorescence parameters such as the ɸPSII, Fv′/Fm′, qP, qN, ETR and ETR/A had high loading scores and correlated with WUEi, the ɸPSII, qP and ETR under DS conditions. The study identified drought-tolerant accessions, namely LS05, LS06, LS07 and LS08 based on high A, T, Fm′, Fv′/Fm′ and ETR, and LS10, LS11, LS18 and LS23 based on high AES, Ci, Ci/Ca, WUEi, WUEins, ɸPSII and AES. The selected genotypes are high yielding (≥5 g pods/plant) under drought stress conditions. The data presented will complement phenotypic data and guide breeding for water-limited agroecologies. Eight selected okra genotypes were crossed in the fourth part of the study to generate new genetic combinations and breeding populations. The parents were selected based on their high yield potential and tolerance to drought stress. The genotypes were sourced from the Agricultural Research Council-Vegetable, Industrial and Medicinal Plants (ARC-VIMP), South Africa, assembled from diverse regions of origin. The selected eight parents were crossed using an 8 × 8 half diallel mating design during the 2021 cropping season. The parents were planted under field conditions at the ARC-VIMP research station during the 2021/2022 growing season. Subsequently, 28 new generations were developed. The crosses and eight parents were field evaluated using a 12 × 3 lattice design with three replications. The genotypes were evaluated under NS and DS conditions at two locations, namely the ARC – Loskop and ARC – Brits sites. Significant (P<0.01) effects of genotype, environment, and genotype × environment interaction was recorded for fresh pod yield and component traits. General combining ability (GCA) and specific combining ability (SCA) effects were significant (P<0.05) for most traits, indicating the role of additive and non-additive gene action underlying the inheritance of the assessed traits. The GCA × environment and SCA × environment interaction effects were significant for days to flowering (DTF), number of leaves per plant (NOL), fresh pod length (FPL), number of fresh pods per plant (NFPP) and pod yield per plant (PYP). Parental genotypes LS09, LS10 and L24 showed positive GCA effects for PYP under DS conditions and were selected to be valuable germplasm for variety design to widen genetic variability for drought tolerance and yield-related traits. Crosses LS01 × LS17, LS01 × LS18, LS09 × LS10, LS09 × LS18, LS09 × LS24, LS15 × LS18, LS15 × LS21, LS15 × LS24 and LS17 × LS21 expressed positive SCA effects for PYP under DS condition and are recommended for genetic advancement, production, and commercialization in water-scarce environments of South Africa. Overall, the study discerned considerable genetic diversity among the evaluated okra genotypes. Further, the study selected parental lines and new families with good product profiles, drought tolerance and combining ability for genetic advancement and variety design for water-limited environments in South Africa and similar agroecologies.
Pre-breeding of sorghum [sorghum bicolor (L.) moench] for drought tolerance in the semi-arid zones of Nigeria=Ukulungisela ukuzalanisa kweSorghum [Sorghum bicolor (L.) Moench] Yokubekezelela Isomiso Ezindaweni Ezomile ZaseNigeria.
(2023) Yahaya, Muhammad Ahmad.; Shimelis, Hussein Ali.
Sorghum [Sorghum bicolor (L.) Moench] is a staple food crop serving millions of people in Africa and Asia's arid and semi-arid agro-ecologies. Sorghum is widely cultivated in Northern Nigeria, serving diverse value chains, including the food and feed sectors and the brewery industry. However, the potential production and productivity of sorghum in Africa, including Northern Nigeria, is constrained by severe drought stress associated with climate change. Furthermore, smallholder farmers in Nigeria still cultivate low-yielding and drought-susceptible unimproved sorghum landraces. Developing drought-tolerant sorghum cultivars adapted to semi-arid regions would enhance yield gains and stability with desirable product profiles according to the needs of the farmers and the marketplace. Therefore, the overall objective of this study was to improve sorghum productivity in Nigeria by developing new generation, locally adapted and drought-tolerant varieties. The specific objectives of this study were to: (1) present the current opportunities and constraints to sorghum production in Nigeria and make recommendations as a guide to new variety design and sustainable production, (2) determine drought tolerance and genotype-byenvironment interaction (GEI) effect on grain yield of a population of African sorghum genotypes to identify high-yielding and drought-adapted genotypes for production and breeding, (3) assess the genetic diversity and deduce the population structure among 200 sorghum accessions to guide the selection of contrasting parents for pre-breeding and breeding of drought-tolerant sorghum cultivars and (4) determine the combining ability, heterosis and gene action conditioning agronomic traits and grain yield among sorghum genotypes to select genetically superior and contrasting parental genotypes and new families for drought tolerance breeding, cultivar release and commercialization. In the first chapter, a participatory rural appraisal (PRA) study was conducted in three selected sorghum growing zones in Northern Nigeria involving 250 farmers. Socio-economic data were collected through surveys and focus group discussions. Results showed that sorghum was cultivated mainly by males (80%) who had grade 6-12 level of education (31.3%), with a productive age of 21-45 years (75.7%) and a household family size of below five members (52.3%). Low-yielding landrace varieties such as Kaura (37.4%) and Fara-fara (29.3%) were the most widely cultivated types across the study zones due to their good grain quality. The major farmers' preferred traits from a sorghum variety were high yield, drought tolerance and Striga resistance. The study recommends integrated sorghum technology development incorporating the described preferences of the farmers for sustainable production and economic gains of the crop. The second chapter examined 225 sorghum genotypes assembled from diverse origins to determine drought tolerance and GEI effects on grain yield. The collections were evaluated under non-stressed (NS), pre-anthesis drought stress (PreADS), and post-anthesis drought stress (PoADS) conditions under field and greenhouse environments. The additive main effect and multiplicative interaction (AMMI) analysis revealed that genotype (G), environment (E), and GEI were significant (p<0.05) and accounted for 38.7, 44.6, and 16.6% of the total explained variation in grain yield, in that order. AMMI 4 was the best-fitting model for genotype selection with better grain yield. Based on AMMI 4 and the Best Linear Unbiased Predictors (BLUPs) analyses, genotypes Yar Lazau and Dangama Wulchichi, with a grain yield of 5.6 t/ha and 6.3 t/ha, were selected as being suitable for non-stressed conditions, respectively. Genotypes ICNSL2014-022-4 and Takumbo with BLUPs of 2.5 t/ha and 2.6 t/ha were best-suited for pre-anthesis drought stress conditions, whereas genotypes Danyar Bana and Gagarau - 4 with BLUPs of 4.2 t/ha and 4.3 t/ha are recommended for post-anthesis drought-prone environments, respectively. The identified sorghum genotypes are valuable genetic resources to develop novel drought tolerance cultivars or for production in dry agro-ecologies of sub-Saharan Africa characterized by pre-and-post anthesis drought stress. In the third chapter, diversity arrays technology (DArT) –derived single nucleotide polymorphism (SNP) markers were used to assess the genetic diversity and discern the population structure of 200 sorghum accessions to select complementary lines for breeding. The markers have moderate discriminatory power, with the polymorphism information content ranging between 0.09 to 0.38. The average gene diversity value (0.32) was high, while the average observed heterozygosity (0.15) was relatively low, a typical value for autogamous crop species like sorghum. The population structure and cluster analyses revealed four main clusters with a high level of genetic diversity among the accessions studied. The variation within populations (41.5%) was significantly higher than that among populations (30.8%) and between samples within a structure (27.7%). The high genetic variation within the population could be attributed to the preservation of sorghum landraces by farmers and differences in the genetic constitution, adaptation and parentage. The study identified distantly related sorghum accessions such as Samsorg 48, Kaura Red Glume (from Cluster 1); Gadam, AS 152 (Cluster 2); CSRO1, ICNSL2014−062 (Cluster 3); and Yalai, Kafi Mori (Cluster 4) useful in developing new gene pools and novel genotypes for the West and Central Africa (WCA) sorghum breeding programs. Based on the phenotypic and genotypic data, 12 contrasting parents were selected for breeding population development with high yield and drought tolerance. In the last chapter, 12 contrasting sorghum parents were selected from a diverse set of 225 genotypes exhibiting variable agronomic traits, including high grain and drought tolerance and farmer-preferred attributes. The 12 parents were crossed using a half-diallel mating design to create 66 F1 progenies. The F1 progenies, the parents, and two check varieties were evaluated under three environments in Nigeria. The results revealed the presence of significant variations amongst test genotypes allowing the selection of suitable parents and hybrids for traits of interest. The contribution of the specific combining ability (SCA) variance to total variance was higher than that of the general combining ability (GCA) for most of the studied traits, indicating that nonadditive gene action was more dominant in conditioning trait inheritance. GCA x environment and SCA x environment interaction effects were significant (p<0.05) for days to anthesis, aboveground biomass and grain yield. Parental genotypes Samsorg 7, Masakwa, and SSV2008091, recorded significant and positive GCA effects for grain yield and are useful germplasm resources for breeding high-yielding cultivars. Crosses AS 152 x SSV2008091, Samsorg 7 x Kurumbasau, AS 152 x ICNSL2014-022-8, and Masakwa x Hindatu exhibited high and positive SCA effects and were the top performers recording above-ground biomass yield of 29.3, 23.4, 27.2 and 16.5 t/ha and grain yield of 6.4, 6.6, 6.6 and 6.5 t/ha, in that order. The crosses exhibited high parent heterosis for grain yield and other agronomic traits, revealing that hybrid breeding is an effective strategy for boosting sorghum production. The newly selected F1 progenies had higher yields than the local checks and are recommended for hybrid or pure line breeding and variety release in Nigeria's drought-prone areas and similar sub-Saharan Africa (SSA) agro-ecologies after continuous selection and multi-environment testing. Overall, the study identified drought stress as the most critical sorghum production constraint in Northern Nigeria. Also, the study highlighted significant genetic diversity among the test genotypes. Best performing genotypes Yar Lazau, ICNSL2014-022-4 and Danyar Bana were selected as suitable for non-stressed, pre-anthesis and post-anthesis drought stress conditions, respectively. The selected genotypes are recommended for production or breeding in droughtprone areas. In addition, the study identified drought-tolerant and early-maturing genotypes (e.g., Samsorg 7, Masakwa, and SSV2008091) with good general combining ability effects for breeding population development and heterosis breeding in the semi-arid region of Northern Nigeria. IQOQA Amabele [Sorghum bicolor (L.) Moench] iyisivuno sokudla okuyinhloko esiphakela izigidi zabantu e-Afrika kanye ne-agro-ecologies eyomile necishe koma yase-Asia. Amabele atshalwa kakhulu eNyakatho yeNigeria, asetshenziselwa uchungechunge lwezinto ezahlukahlukene, kufaka phakathi imikhakha yokudla kanye nomkhakha wokuphiswa kotshwala. Kodwa-ke, ukukhiqizwa okungenzeka kanye nomkhiqizo wamabele e-Afrika, kufaka phakathi iNyakatho yeNigeria, kucindezelwa ukucindezeleka okukhulu kwesomiso okuhambisana nokuguquka kwesimo sezulu. Ngaphezu kwalokho, abalimi abancane eNigeria basalima amabele akhiqiza kancane nesezindaweni ezizwelayo esomisweni. Ukuthuthukisa kokutshalwa kohlobo lwamabele abekezelela isomiso ezifundeni ezomile kungathuthukisa ukuzuza kwesivuno nokuzinza ngamaphrofayili omkhiqizo ofiselekayo ngokwezidingo zabalimi kanye nendawo yemakethe. Izinhloso ngqo zalolu cwaningo zazithi: (1) ukwethula amathuba amanje kanye nezingqinamba zokukhiqiza amabele eNigeria futhi wenze izincomo njengesiqondiso sokuklama izinhlobonhlobo ezintsha kanye nokukhiqizwa okuqhubekayo, (2) ukunquma ukubekezelela isomiso kanye nomphumela wokusebenzisana kwegenotype-by-environment (GEI) ekuvuneni okusanhlamvu kwabantu be-African sorghum genotypes ukuhlonza amagenotypes aphezulu futhi avumelaniswe nesomiso sokukhiqiza nokuzala, (3) ukuhlola ukuhlukahluka kwezakhi zofuzo nokuthola isakhiwo sokusabalala phakathi kokufinyelela kwamabele angama-200 ukuqondisa ukukhethwa kwabazali abahlukile bokuzalanisa kwangaphambili nokuzalanisa amacultivars amabele abekezelela isomiso futhi (4) ukunquma ikhono lokuhlanganisa, iheterosis kanye nesenzo segene esilungisa izici ze-agronomic kanye nesivuno sokusanhlamvu phakathi kwamagenotypes amabele ukukhetha amagenotypes aphakeme ngofuzo futhi ahlukile wabazali kanye nemindeni emisha yokuzalanisa ukubekezelelana kwesomiso, ukukhululwa kwecultivar nokuthengisa. Esahlukweni sokuqala, ucwaningo lwe- participatory rural appraisal (PRA) lwenziwe ezindaweni ezintathu ezikhethiwe zokukhulisa amabele eNyakatho yeNigeria ezibandakanya abalimi abanga-250. Imininingwane yezenhlalo nezomnotho yaqoqwa ngokusebenzisa inhlolovo kanye nezingxoxo zeqembu lokugxila. Imiphumela ikhombise ukuthi amabele alinywa ikakhulukazi ngabesilisa (80%) ababenezinga lemfundo lebanga le-6-12 (31.3%), abaneminyaka ekhiqizayo yeminyaka engama-21-45 (75.7%) kanye nobukhulu bomndeni wasekhaya obungaphansi kwamalungu amahlanu (52.3%). Izinhlobo zomhlaba ezithela kancane ezifana neKaura (37.4%) neFara-fara (29.3%) zaziyizinhlobo ezitshalwa kakhulu kuzo zonke izindawo zokufunda ngenxa yekhwalithi yazo enhle yokusanhlamvu. Izici ezikhethiwe zabalimi abakhulu ezivela ezinhlobonhlobweni zamabele zaziyisivuno esiphezulu, ukubekezelela isomiso nokumelana neStriga. Ucwaningo luncoma ukuthuthukiswa kobuchwepheshe obuhlanganisiwe bamabele okufaka izintandokazi ezichaziwe zabalimi zokukhiqiza okuqhubekayo kanye nokuzuza kwezomnotho kwesivuno. Isahluko sesibili sihlole amagenotypes anga-225 amabele ahlanganiswe kusuka ezimvelaphini ezahlukahlukene ukunquma ukubekezelela isomiso nemiphumela ye-GEI ekuvuneni okusanhlamvu. Amaqoqo ahlolwe ngaphansi kwezimo ezingacindezelekile, ezinon-stressed (NS), ukucindezeleka kwesomiso sangaphambi kwe-anthesis, ipre-anthesis drought stress (PreADS), kanye nepost-anthesis drought stress (PoADS) ngaphansi kwezindawo zensimu kanye negreenhouse. Umphumela oyinhloko wesengezo kanye nokuhlaziywa kokusebenzisana kwemultiplicative (AMMI) kuveze ukuthi igenotype (G), imvelo okuyi-environment (E), ne-GEI yayibalulekile (p<0.05) futhi yaba ngama-38.7, 44.6, ne-16.6% wokuhlukahluka okuphelele okuchaziwe kwesivuno sokusanhlamvu, ngaleyo ndlela. I-AMMI 4 yayiyimodeli efaneleka kakhulu yokukhethwa kwegenotype ngesivuno esingcono sokusanhlamvu. Ngokusekelwe ekuhlaziyweni kwe-AMMI 4 kanye neBest Linear Unbiased Predictors (BLUPs), amagenotypes uYari Lazau noDangama Wulchichi, ngesivuno sokusanhlamvu se-5.6 t / ha ne-6.3 t / ha, bakhethwa njengabafanele izimo ezingacindezelekile, ngokulandelana. IGenotypes ICNSL2014-022-4 neTakumbo enama-BLUP we-2.5 t / ha ne-2.6 t / ha yayilungele kakhulu izimo zokucindezeleka kwesomiso sangaphambi kwe-anthesis, kanti amagenotypes Danyar Bana noGagarau - 4 nge-BLUPs ye-4.2 t / ha ne-4.3 t / ha kunconywa ezindaweni ezithambekele esomisweni ngemuva kwe-anthesis, ngokulandelana. Igenotypes yamabele ehlonziwe iyimithombo yofuzo eyigugu ukuthuthukisa amacultivars okubekezelela isomiso senoveli noma ukukhiqizwa kuma-agro-ecologies omile e-Afrika engezansi kweSahara ebonakala ngokucindezeleka kwesomiso sangaphambi kokuthunyelwe kwe-anthesis. Esahlukweni sesithathu, idiversity arrays technology (DArT) – nezimpawu amaderived single nucleotide polymorphism (SNP) kwasetshenziselwa ukuhlola ukuhlukahluka kwezakhi zofuzo nokuqonda isakhiwo senani sokufinyelela kwamabele okungama-200 ukukhetha imigqa ehambisanayo yokuhiqiza. Izimpawu zinamandla okubandlulula ngokulinganisela, ngokuqukethwe kolwazi lwepolymorphism okuphakathi kuka-0.09 kuya ku-0.38. Inani elijwayelekile lokuhlukahluka kwezakhi zofuzo (0.32) laliphezulu, kanti isilinganiso sabona iheterozygosity (0.15) yayiphansi kakhulu, inani elijwayelekile lezinhlobo zezitshalo ze-autogamous njengamabele. Isakhiwo senani kanye nokuhlaziywa kweqoqo kwaveza amaqoqo amane aphambili anezinga eliphezulu lokuhlukahluka kwezakhi zofuzo phakathi kokufinyelela kokufundiwe. Ukuhlukahluka ngaphakathi kwenani (41.5%) kwakuphakeme kakhulu kunalokho phakathi kwenani (30.8%) naphakathi kwamasampula ngaphakathi kwesakhiwo (27.7%). Ukuhlukahluka okuphezulu kwezakhi zofuzo ngaphakathi kwenani kungabangelwa ukulondolozwa komhlaba wamabele ngabalimi kanye nokwehluka komthethosisekelo wofuzo, ukuzivumelanisa nezimo kanye nokuba ngumzali. Ucwaningo luveze ukufinyelela kwamabele okuhlobene kude njengeSamsorg 48, i-Kaura Red Glume (kusuka ku-Cluster 1); Gadam, AS 152 (Cluster 2); CSRO1, ICNSL2014−062 (Cluster 3); noYalai, uKafi Mori (Cluster 4) owusizo ekuthuthukiseni amachibi amasha ezakhi zofuzo kanye namagenotypes amasha ezinhlelo zokuzalanisa amabele zaseNtshonalanga naphakathi ne-Afrika (WCA). Ngokusekelwe emininingweni yephenotypic negenotypic, abazali abayi-12 abaphikisanayo bakhethwa ukuthuthukisa inani lesivuno esiphezulu nesinokubekezelela isomiso. Esahlukweni sokugcina, imithombo eyi-12 eyahlukene yamabele yakhethwa esethini ehlukahlukene yamagenotypes anga-225 abonisa izici eziguquguqukayo ze-agronomic, kufaka phakathi okusanhlamvu okuphezulu nokubekezelela isomiso kanye nezici ezikhethiwe zomlimi. Imithombo eyi-12 yaxutshwa kusetshenziswa umklamo wokukhwelana wesigamu sediallel ukudala inzalo ye-66 F1. Inzalo ye-F1, imthombo, kanye nezinhlobo ezimbili zokuhlola zahlolwa ngaphansi kwezindawo ezintathu eNigeria. Imiphumela yaveza ukuba khona kokuhlukahluka okuphawulekayo phakathi kwamagenotypes okuhlola okuvumela ukukhethwa kwemithombo efanelekayo kanye namahybrid ezici ezithakazelisayo. Umnikelo ispecific combining ability (SCA) ukuhlukahluka kokuhlukahluka okuphelele kwakuphakeme kunalokho kwekhono igeneral combining ability (GCA) iningi lezici ezifundiwe, okubonisa ukuthi isenzo segene esingangeziwe sasibusa kakhulu esimweni sefa lesici. I-GCA x imvelo kanye ne-SCA x imvelo kwakubalulekile (p<0.05) ezinsukwini kuya ku-anthesis, ngaphezu kwebiomass yomhlaba kanye nesivuno sokusanhlamvu. Amagenotypes awumthombo i-Samsorg 7, i-Masakwa, ne-SSV2008091, aqophe imiphumela ebalulekile futhi emihle ye-GCA yesivuno sokusanhlamvu futhi ayimithombo ewusizo yegermplasm yokuzalanisa amacultivars aphezulu. Ukuxutshwa kwe-AS 152 x SSV2008091, i-Samsorg 7 x Kurumbasau, i-AS 152 x ICNSL2014-022-8, ne-Masakwa x Hindatu kubonise imiphumela ephezulu futhi emihle ye-SCA futhi yayingabadlali abaphezulu abaqopha isivuno se-biomass esingaphezulu komhlaba we-29.3, 23.4, 27.2 ne-16.5 t / ha kanye nesivuno sokusanhlamvu se-6.4, 6.6, 6.6 no-6.5 t / ha, ngaleyo ndlela. Ukuxuba kwabonisa iheterosis ephezulu yomthombo wesivuno sokusanhlamvu nezinye izici ze-agronomic, eveza ukuthi ukuzalanisa ihybrid kuyindlela ephumelelayo yokukhulisa ukukhiqizwa kwamabele. Inzalo esanda kukhethwa ye-F1 yayinesivuno esiphezulu kunokuhlolwa kwendawo futhi inconywa ukuzalanisa umugqa wehybrid noma ohlanzekile kanye nokukhishwa kwezinhlobonhlobo ezindaweni zaseNigeria ezithandwa isomiso kanye ne-agro-ecologies efanayo yesub-Saharan Africa (SSA) ngemuva kokukhethwa okuqhubekayo nokuhlolwa kwemvelo eningi. Sekukonke, ucwaningo lwaveza ukucindezeleka kwesomiso njengengcindezi ebucayi kakhulu yokukhiqiza amabele eNyakatho Nigeria. Futhi, ucwaningo lwaqhakambisa ukuhlukahluka okuphawulekayo kwezakhi zofuzo phakathi kwamagenotypes okuhlola. Amagenotypes enza kahle kakhulu uYar Lazau, ICNSL2014-022-4 noDanyar Bana akhethwa njengafanelekile ezimweni zokucindezeleka ezingacindezelekile, zangaphambi kwe-anthesis kanye nezimo zokucindezeleka kwesomiso ngemuva kwe-anthesis, ngokulandelana. Amagenotypes akhethiwe anconywa ukukhiqizwa noma ukuzala ezindaweni ezithambekele esomisweni. Ngaphezu kwalokho, ucwaningo lwaveza amagenotypes abekezelela isomiso futhi avuthwa ekuqaleni (isib., iSamsorg 7, iMasakwa, ne-SSV2008091) ngemiphumela emihle ejwayelekile yokuhlanganisa ikhono lokuthuthukiswa kwenani elizalayo kanye nokuzalanisa iheterosis esifundeni esomile saseNyakatho Nigeria.
Responses to chilling and cryopreservation of recalcitrant seeds of Ekebergia capensis from different provenances.
(2020) Bharuth, Vishal Behary Lal.; Beckett, Richard Peter.; Pammenter, Norman William.
Recalcitrant seeds are shed at relatively high water contents and are metabolically active. The effect of chilling the recalcitrant seeds of purportedly a single species, Ekebergia capensis, from Port Elizabeth (PE; Eastern Cape), St Lucia (KwaZulu-Natal [KZN]) and Tanzania (tropical southern Africa) was tested. Viability and axis ultrastructure, solute leakage and protein synthesis were investigated. Additionally, cryopreservation of embryonic axes (explants) was studied. In particular, the ability of cathodic water to improve explant survival was tested, and related to its effect on the production of potential harmful reactive oxygen species such as superoxide (·O2-) and hydrogen peroxide (H2O2), and its ability to maintain levels of total aqueous antioxidants (TAA). Shoot and root ultrastructure were examined after each cryopreparative step in explants treated with and without cathodic water, and ultrastructure correlated with survival. The seeds from PE retained 80% viability after 12 weeks storage at 1° and 3°C and 100% when stored at 6°C. Those from St Lucia were dead after 38 d storage at 3°C. All the seeds from Tanzania were dead after 9 d when stored at 3°C. The rate of protein synthesis decreased gradually over the storage period, irrespective of the provenance. Electrolyte leakage from axes showed that those from St Lucia and Tanzania ‘leaked’ solutes irrespective of the duration or temperature or storage, but those from PE showed an initial increase, which then decreased. A 30% mass loss was achieved after 48 d, 230 h and 21 h for seeds from PE, St Lucia and Tanzania, respectively. Nuclear ribosomal ITS1 sequences revealed the presence of three well-to-strongly-supported monophyletic clades corresponding to the geographical areas from which the seeds were sampled (PE, KZN and Tanzania). Axes from the seeds from St Lucia and Tanzania lost ultrastructural integrity during storage while those from PE did not. The levels of ·O2- and H2O2 increased gradually after each cryopreparative step. Using cathodic water allowed 30% of PE explants to survive cryopreservation, while none of the St Lucia explants did. Root ultrastructure was well preserved, however, gradual ultrastructural deterioration was observed in the shoot meristem.
Screening acacia mearnsii (black wattle) seedlings for frost tolerance using an artificial frost technique, combined with proteomic analysis.
(2023) Jugmohan, Mayuri.; Laing, Mark Delmege.; Bairu, Michael Wolday.; Chan, Julian Moreno.
Acacia mearnsii de Wild. (commonly known as black wattle), was first introduced to South Africa in the 1800’s. Today, it is one of the leading commercially grown forestry crops in South Africa due to its usefulness and versatility. Black wattle is a source of high-quality tannin and raw material for wood pulp. It is also excellent for building and as a source of firewood. These uses have contributed to its popularity as a crop for both commercial farmers and small growers. Since its introduction to South Africa, abiotic stresses such as frost damage have affected the silviculture of black wattle, and this has resulted in major financial losses for the forestry industry. Over several decades, breeding research has been conducted with the aim of developing genetically improved seed for frost prone areas. However, this has yet to be achieved. Screening for frost tolerance in black wattle has mainly been conducted using field trials. While this provides the most realistic means of screening, it has several challenges. Field trials are time consuming, expensive and require much effort. Furthermore, frost events are unpredictable in timing and in magnitude, thus affecting frost damage screening trials, with levels of zero to extreme frost occurring in any one year at a selected site. This does not allow for a productive plant breeding program to consistently screen for frost tolerance. The current study focussed on the development of an artificial frost screening method for black wattle. A protocol comprising of eight days of moderately cold temperatures (adaptation) and one day of extremely cold temperature (frost tolerance) was established using a temperature-controlled chamber. The frost damage that resulted from the implementation of this protocol produced similar levels of damage as those experienced in previous field trials. This protocol was thereafter tested in two separate trials involving 100 families of wattle accessions that had previously been ranked in field trials that had been run in frost prone areas. A weak correlation was observed between the results of the artificial frost screening trials and the corresponding field results (r=0.24 to 0.28, rs=0.20 to 0.28). Kruskal-Wallis tests showed a statistical similarity between the medians of one of the artificial frost screening trials and the field frost damage evaluations, and a significant difference between the medians of the two artificial frost screening trials that were conducted. The understanding of the molecular aspects that contribute towards frost tolerance in black wattle is extremely limited. Several studies involving a molecular approach to understanding this trait in other woody species have shown promising results. Frost tolerance is a multigenic trait and therefore a proteomic approach was chosen as the best option to identify biomarkers associated with it. Protein extraction from black wattle has not been previously conducted and therefore a protocol that dealt with the interference of phenolics and that was compatible with downstream proteomic techniques was developed. During the protein extraction protocol development, three different protein extraction methods were compared. These methods differed in terms of their precipitation agent combinations. These combinations included acetone and methanol, phenol and ammonium acetate and ammonium acetate and methanol. The combination of phenol and ammonium acetate produced the highest protein yield, as well as the most distinct protein spots after separation by two-dimensional gel electrophoresis. This method was used to extract proteins from 40 black wattle families with varying levels of frost tolerance, before and after cold stress treatment. These extracted proteins were thereafter separated using two-dimensional gel electrophoresis so that changes in protein expression as a result of cold exposure could be analysed. Multivariate analyses of the proteomic data revealed that six proteins were upregulated in frost-tolerant black wattle families. The identified proteins were: two isoforms of oxygen-evolving enhancer protein 1, probable 1-acyl-sn-glycerol-3-phosphate acyltransferase 4, ribulose bisphosphate carboxylase/oxygenase activate, chaperonin 60 subunit alpha 1 and stromal 70 kDa heat shock-related protein. After identification by mass spectrometry, it was established that these proteins have previously been shown to contribute to the protection of cellular membranes, maintenance of photosynthetic processes and the prevention of protein misfolding and aggregation. These proteomic functions have been observed in previous studies to be associated with the process of cold acclimation in plants and thus seem to play a role in frost tolerance in black wattle. The establishment of an artificial frost screening protocol and the proteomic profiling of black wattle for frost tolerance are important tools for preliminary screening of families prior to field trials. By using these protocols fewer black wattle families will require field testing. This will be beneficial both in terms of cost, effort and time associated with field trials. The development of artificial methods for the induction of stresses and the proteomic changes that result from these are valuable tools for understanding the mechanisms that plants use to cope with abiotic and biotic threats.
Structural, nutritional and protein functional properties of trichilia emetica and trichilia dregeana seeds=Izakhiwo Zesakhiwo, Ukudla Kanye Namaprotheni Asebenzayo Embewu ye-Trichilia emetica ne-Trichilia dregeana.
(2022) Tsomele, Gugu Felicity.; Siwela, Muthulisi.; Wokadala, Obiro Cuthbert.
Food and nutrition insecurity are prevalent in developing regions, especially in the predominantly low-economic status of sub-Saharan Africa. Yet, several edible domesticated and wild plants are grossly under-utilised as food sources. The woody plants Trichilia species are indigenous to Africa and are also found in other developing countries. Although the oily seeds of Trichilia species seem to have great potential for contributing towards the alleviation of malnutrition in the developing regions, they are grossly under-utilised and there is a dearth of scientific literature regarding their nutritional potential. To improve the utilisation of Trichilia seeds on a commercial scale, it is vital to study their physical characteristics and the nutritional and food-related (functional) physico-chemical properties of their components. In this study, the structural and chemical composition of Trichilia emetica (T. emetica) and Trichilia dregeana (T. dregeana) seeds, in addition to the nutritional and functional properties of their proteins, were investigated and compared with the soybean. The results of the seeds analysis showed that Trichilia seeds had difficulty sliding on surfaces due to their oblate shape. Trichilia seeds showed lower sphericity (0.66) than soybean (0.99), with higher bulk density (645.9 kg/m3 and 433.6 kg/m3, respectively) and lower true density (875.8 kg/m3 and 950.4 kg/m3, respectively). The porosities for T. emetica and T. dregeana were significantly lower (55.07% and 54.38%), with a higher geometric mean diameter (29.7mm and 16.9 mm) than soybean. Trichilia species showed similar shapes, but different localisation of the seeds‟ protein bodies when compared with soybean. Trichilia seeds‟ protein bodies were larger in size and more round in shape than those of the soybean. The other investigations in this study determined the nutritional properties of the flour and protein of T. emetica and T. dregeana seeds, and compared the chemical structure and functional properties of protein in the Trichilia seeds with the soybean. The results showed that T. emetica and T. dregeana seeds contained substantial protein (25.6% and 17.3%, respectively) and high concentrations of fat (49% and 51.5%, respectively). Potassium, calcium, iron and zinc were the major minerals in the Trichilia seeds. T. emetica and T. dregeana protein had substantial concentrations of Phenylalanine, Leucine, Isoleucine, Valine and Lysine and Methionine, which were comparable with those of the soybean. The concentrations of essential amino acids in Trichilia seeds, similar to their concentrations in soybean, were above the recommended Food and Agricultural Organisation standards for adults. The proportion of essential amino acids to total amino acids of T. emetica and T. dregeana seeds was similar to that of the soybean. The Trichilia spp protein had more β-conformation than α-helices (21%) comparable with soybean protein. The protein concentrates of T. emetica seed had higher Water holding Capacity, Foaming Capacity and Foaming Stability with lower Oil holding Capacity and Emulsion activity Index when compared with soybean and T. dregeana seeds. The findings of the current study indicate that the physical and nutritional properties of T. emetica and T. dregeana seeds and their protein properties had comparable properties to existing commercial oilseeds. This could improve the utilisation of the seeds as complementary foods and can cause an increase in the number of available food sources for food and nutrition security, thereby improving the livelihoods of individuals. However, there would be a need to modify the existing technologies for drying, milling, packaging and transportation to accommodate the Trichilia seeds. Furthermore, the bioavailability of the minerals and protein of the Trichilia seeds should be assessed. Iqoqa Izitshalo ezinokhuni eziyizinhlobo zeTrichilia ziyindabuko e-Afrika futhi zitholakala nakwamanye amazwe asathuthuka. Nakuba imbewu enamafutha yezinhlobo zeTrichilia ibonakala inamandla amakhulu okufaka isandla ekunciphiseni ukungondleki ezifundeni ezisathuthuka, isetshenziswa kancane kakhulu, ikakhulukazi ngoba ayicwaningwa kakhulu, ngokwesayensi. Kulolu cwaningo, ukwakheka kwesakhiwo namakhemikhali eTrichilia emetica (T. emetica) kanye nembewu yeTrichilia dregeana (T. dregeana), ngaphezu kwezakhi zokudla nokusebenza kwamaprotheyni ako, kwaphenywa futhi kuqhathaniswa nobhontshisi wesoya. Imiphumela ibonise ukuthi imbewu yeTrichilia yayinesphericity ephansi (0.66) kunesoybean (0.99), enenqwaba ephezulu (645.9 kg/m3 and 433.6 kg/m3, ngokulandelana) kanye nobuningi beqiniso obuphansi (875.8 kg/m3 and 950.4 kg/m3, ngokulandelana). Amaporosities e-T. emetica ne-T. dregeana ayephansi kakhulu (55.07% no-54.38%), ngegeometric ephakeme isho ububanzi (29.7 mm no-16.9 mm) kunobhontshisi wesoya. Imizimba yamaprotheyni yembewu yezinhlobo zeTrichilia yabonisa izimo ezifanayo, kodwa indawo ehlukile futhi yayinkulu futhi ijikeleza kakhulu uma iqhathaniswa nobhontshisi wesoya. Ucwaningo lwathola ukuthi imbewu ye-T. emetica ne-T. dregeana iqukethe amaprotheyni amakhulu (25.6% no-17.3%, ngokulandelana) kanye nokujiya okuphezulu kwamafutha (49% no-51.5%, ngokulandelana). IPotassium, icalcium, i-iron nezinc kwakungamaminerali amakhulu embewini yeTrichilia. Amaprotheyni embewu yeTrichilia spp emibili ayenokujiya okukhulu kwama-amino acid abalulekile iPhenylalanine, iLeucine, i-Isoleucine, iValine neLysine neMethionine, eyayiqhathaniswa naleyo kabhontshisi wesoya futhi ngaphezu kwamazinga Enhlangano Yokudla Nezolimo anconyiwe kubantu abadala. Amaphrotheyni embewu yeTrichilia spp ayene-β- conformation kakhulu kune-α-helices (21%), eyayiqhathaniswa namaprotheyni kabhontshisi wesoya. Amaprotheyni okugxila kwembewu ye-T. emetica kwakunezinga eliphakeme lokumumatha amanzi, iFoaming Capacity kanye neFoaming Stability ene-Oil holding Capacity ephansi kanye nomsebenzi we-Emulsion Index uma kuqhathaniswa nembewu yesoybean ne-T. dregeana. Sekukonke, okutholakele kubonisa ukuthi, ngemuva kokuguqulwa okuthile okudingekayo kwemishini yokucubungula yamanje, imbewu yeTrichilia ssp ingasetshenziswa endaweni yezimbewu zikashukela zokuhweba ezisetshenziswa njengamanje njengesoyabean, ezifundeni ezisathuthuka lapho iTrichilia ssp ivuma kakhulu.
The effect of varying dietary nutrient densities on performance: experimental investigations on the response of broiler chickens to different energy and lysine levels.
(2024) Ndlebe, Loyiso.; Ciacciariello, Mariana.; Tyler, Nicola Claire.
The overall objective of the study was to determine the influence of varying dietary apparent metabolizable energy (AMEn) and digestible lysine (dLys) inclusion levels on the overall growth performance of Cobb 500 broilers. Two experiments were conducted, and in each experiment a total of 1440 unsexed day-old Cobb 500 broiler chicks were randomly allocated to one of 48 pens (i.e. 30 chicks per pen) in a completely randomized block design. In experiment 1, the effect of incremental changes in dietary AMEn while maintaining a constant dLys: AMEn ratio was assessed. Experimental diets were formulated to contain eight different dietary AMEn concentrations ranging from 11.30 to 13.05 MJ/kg (+0.25MJ/kg) respectively, while adjusting dLys levels tomaintain a constant dLys: AMEnratio of 0.97. The broilers received a common broiler started diet for a period of 14 days, after which the experimental diets were introduced (Day 14-35 of the trial). Feed intake decreased linearly with incremental changes in dietary AMEn. Dietary AMEn intake and energy efficiency ratio (EER) differed significantly between treatments. Dietary AMEn increased linearly with incremental changes in AMEn, while EER exhibited a quadratic response. No significant differences in body weight gain (BWG) were observed for the entire treatment period (Day 14-35). According to the response curve equation (𝑌 = −58.952𝑥2 + 1473.9 − 6937.9), BWG was optimised at 12.55 MJ/kg. Increasing AMEn while maintaining the dLys: AMEn ratio improved feed conversion ratio (FCR), and significant differences occurred between the lowest and the highest nutrient densities. In experiment 2, the influence of varying dietary dLys levels in isoenergetic diets was evaluated. Experimental diets were formulated to contain eight different dietary dLys levels ranging from 0.95 to 1.30% (+0.05%). Dietary AMEn concentration was kept constant at 12.1 MJ/kg giving dLys: AMEn ratios 0.78, 0.83, 0.87, 0.91, 0.95, 0.99, 1.03 and 1.07. The broilers were fed a common broiler started diet for the first 14days, whereafter the experimental diets were fed from Day 14-35 of Experiment 2. Feed intake and AMEn intake were not affected by the incremental changes in dietary dLys. Energy efficiency ratio, dLys intake and digestible lysine ratio (dLysER) differed significantly between dietary treatments. Digestible Lys intake increased, while dLysER decreased with an increase in dLys inclusion level. Overall, BWG differed significantly between treatment groups, with an increasing quadratic response (𝑌 = −1119𝑥2 + 2871.7𝑥 + 301.11, 𝑃 < 0.05). Feed conversion ratio decreased (improved) linearly with increasing dLys levels. It can be concluded that broilers can sustain optimal growth performance in a range of dietary AMEn concentrations, provided that an ideal balance between dietary AMEn and nutrients is maintained. Furthermore, adjusting the dLys: AMEn ratio when feeding one dietary AMEn concentration for growing and finishing will optimise broiler performance. Keywords: broiler, digestible lysine, dietary energy, apparent metabolizable energy, energy concentration; digestible lysine: energy ratio; performance
The utilization of amaranthus leaf powder to supplement ujeqe (steamed bread) wheat flour for the alleviation of food and nutrition insecurity in Empangeni South Africa.
(2023) Olusanya, Ruth Nachamada.; Unathi, Kolanisi.; Ngobese, Nomali Ziphorah.; Mayashree, Chinsamy.
Malnutrition persists in many developing countries, leading to an increased concern in the farming sector to deliver at least 70% of food to feed 40% of the anticipated global population of nine billion persons by the year 2050. Such projections call for a keen interest in studies that explore underutilised edible crops for food and nutrition security of the world’s growing population. Malnutrition of all forms including micronutrient deficiencies, “called hidden hunger”, is currently an issue of concern. About 870 million people across the globe are unable to access sufficient nutritious food that optimises dietary needs. Also, 98% of this hungry population live in the developing countries, where 15% of the population is undernourished, Susceptible persons to malnutrition identified include infants, young children, and young women of childbearing age. The impact of malnutrition impairs children’s vision at an early age, slows down cognitive development and retards general development. All forms of malnutrition are nutrient-related preventable challenges; however, it is identified as the leading factor to most morbidity and mortality rates; which limits the livelihoods of many individuals especially smallholder farmers who are residents in informal settlements of urban centres and rural communities. A food-based approach where available nutrient-dense food is incorporated as an ingredient in staple food has been identified as a good strategy to tackle malnutrition. Amaranthus is an ancient C4 plant, a drought tolerant plant that requires little attention yet maximum yield; with huge potential to provide food for nutrition security. Adequate nutrition, at the household level, is indispensable for the proper functioning of the human system and well-being. However, most marginalised, and less privileged people often follow a monotonous starchy/cereal-based diet as this is the available food to fall back on. Extensive studies have shown that about 30 000 varieties of edible plants are dispersed around the world. These plants are cheap, accessible, and highly endowed with medicinal and nutritional benefits. However, only 7000 have been utilised as food while others are underutilised including Amaranthus. It is perceived that most people harvesting Amaranthus leaves for food are the most disadvantaged and marginalised in the rural communities, thus preference issues, perceptions and stigma are linked to Amaranthus underutilisation. Amaranthus seeds have been investigated as enhancers of staple foods. Similarly, leaves of Amaranthus have been identified with great potential to enhance the nutritional value of staple foods for improved nutrition security, optimizing well-being, and improving livelihoods. However, Amaranthus leaves are yet to be explored as a supplement in many traditional foods, including Ujeqe. Online databases of peer-reviewed articles and books were reviewed around the nomenclature, nutritional, and nutraceutical value and objectives were conceived for this study. A mix design (qualitative and quantitative) research method was adopted and a purposive convenience random sampling approach was utilised for the study. Participatory Rural Appraisal (PRA) tools such as transact walks, observation and key informant interviews were conducted. Semi-structured open-ended questionnaires were used to conduct a series of face-to-face interview with six key informants in five markets (n = 30) from urban and rural formal and informal markets where commonly sold/consumed varieties of Amaranthus were identified. Semi-structured questionnaires (100) were administered to gather data around the utilisation of Ujeqe and Amaranthus leaves as potential food for improved nutrition security. A clustered data of (91) respondents was analysed, using descriptive content analysis. The findings of the survey show that Ujeqe is consumed as a meal or as a snack by all people except babies. Also, it is a special meal well appreciated for its simplicity of ingredients and the mode of preparation thus, it is a convenient food that can be served at any time of the day, even in ceremonies, religious functions, and traditional worship of ancestors. Ujeqe’s complementary foods that were identified included legumes and protein-rich foods of animal origin including Usu which are less accessible to the less-privileged hence, some consume it alone as a snack or as a single food. Studies have shown that cereal-based foods without vegetables and fruits are inadequate for optimum well-being because they are lacking/limited in essential nutrients. Amaranthus plants have been investigated as food plant with essential nutrient. Its grains have been used as fortificants, but the leaves have been neglected and its application in Ujeqe steamed bread (USB) is rarely reported in the literature. Amaranthus seeds have been processed into flour and used as food fortificants in staple food. However, the processing of Amaranthus leaves is still very low. Thus, the most common species of Amaranthus grown and sold in formal and informal market in the study site (Amaranthus dubius) was sourced and self-processed into Amaranthus leaf powder (ALP) under a controlled food laboratory environment. The ALP was analysed for macro and micronutrients and utilised to develop 0%, 2%, 4% and 6% prototypes of ALP supplemented Ujeqe which was analysed for macronutrient and micronutrient content. The sensory attributes of ALP supplemented Ujeqe were evaluated using 60 untrained panellists. Moisture content of plain wheat flour (PWF) and ALP in the range 10.6-4.41g; were within the quality shelf-life before usage. The carbohydrate for this study (41.6-74.3g) and fat (1.58- 4.47g) were higher in both raw materials for the study (ALP and PWF). Likewise, the ash (2.37-17.97g) and protein (11.96-31.56g) were recorded as higher in the raw materials for the study. The micronutrient content of the raw materials showed that ALP had a higher nutritional composition than PWF with a statistically significant difference at p < 0.05. Mineral content of calcium was (30.00-2600mg), magnesium (40-120mg), zinc (3.267-7.068mg), copper (1.00- 17.34mg) manganese (1.434-3.00mg) and iron (7.200-24.00mg). The moisture of the ALP enriched Ujeqe prototypes was low, connoting a keeping quality of the shelf-life of the enriched ALP Ujeqe food products. All the macronutrient nutrients of ALP supplemented Ujeqe (Table 3) were enhanced with increased concentration of ALP. The enrichment was noted in the ash content of the 2% (2.2-0.0g), 4% (2.05-0.01g) and 6% prototypes (2.31-0.03g) respectively, with a statistically significant difference at p < 0.05. Likewise, levels of copper, phosphorus, calcium, zinc, manganese, and iron were recorded. All supplemented Ujeqe were enriched in nutrient content. The sensory evaluation indicated that all samples were acceptable. The 6% ALP Ujeqe prototype was the most enriched, but the 2% sample was the most acceptable prototype compared to the control sample followed by 4% and 6% respectively. There was no statistically significant difference in the overall consumer acceptability level of the enriched sample when compared with 0%, 2% and 4% ALP supplemented prototypes. The ALP supplemented Ujeqe was enhanced both in macro and micronutrients. The high ash content of the food samples in this study connotes ALP-supplemented sample richness in mineral content. The mineral content of the raw material, ALP was significantly higher than PWF, supplemented Ujeqe with 6% ALP containing the highest mineral content. Hence, from the nutritional point of view, the formulation was enriched significantly in some selected mineral content. Therefore, ALP supplementation in staple foods like Ujeqe can be a potential foodbased approach that is cost-effective and a sustainable measure for addressing food and nutrition insecurity, especially among the malnourished population. Fibre was not analysed in this study. Thus, future studies can explore ALP-supplemented Ujeqe’s fibre content and microbial tests can be carried out to determine its shelf stability. Continuous research around underutilised food plants including Amaranthus for food and nutrition security can be explored in other staple foods as viable measures to tackle nutrition security. Also, the need for effective implementation of relevant research to help in the domestication of Amaranthus cannot be overemphasised. Thus, improving the small-scale farming of Amaranthus to a larger scale appears to be a realistic way forward. Therefore, the South African government should assist small-scale farmers of Amaranthus with all the extension services needed as this may enhance their productivity and provide food and nutrition security for the community. Similarly, policymakers should consider the provision of land, finance, fertiliser, seeds, herbicides, fences, insecticides, and grants to encourage farmers to plant leafy vegetable foods like Amaranthus for nutrition security. Enhancing small-scale farmer’s capital should involve financial support from the government and the provision of land.

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