Browsing by Author "Odindo, Alfred Oduor."

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Agronomic characterization and evaluation of pigeon pea landraces in KwaZulu-Natal Province of South Africa.
(2015) Hluyako, Lindah London.; Magwaza, Lembe Samukelo.; Odindo, Alfred Oduor.
Abstract available in PDF file.
Assessing the effect of crop intensification in improving aricultural productivity in smallholder farmers' fields : a case study of northern KwaZulu-Natal, South Africa.
(2017) Mthembu, Hloniphile.; Odindo, Alfred Oduor.
Crop intensification is adopted by different countries to address their challenges, which may include low standards of food and nutrition security, limited arable land and land degradation. To assess the effect of crop intensification in improving agricultural productivity in smallholder farmers in Northern KwaZulu-Natal, a qualitative study and in-field experiment were conducted. In a qualitative study the Participatory Rural Appraisal (PRA) tools namely, focus group discussions, transect walks and key informant interviews was used. A random purposive sample of 249 smallholder farmers from 5 local municipalities of uMkhanyakude district was undertaken. The following information was explored: different farming systems; landscape; availability of irrigation systems or water sources; classification of farming soil types; perception of soil fertility; planting and rainfall patterns. Smallholder farmers’ demographics, socio-economic status, typical farming systems, differences between backyard gardens and crop fields, water sources, knowledge and skills on farming systems and practices, understanding and benefits of mixed farming, crop mixing and intercropping, soil fertility and soil acidity management were also explored. The findings of the study revealed that the age of the smallholder farmers ranged between 40-65 years. About 90% of the smallholder farmers who participated in this study were females. 45% of smallholder farmers’ households are headed by females. A typical household of the smallholder farmers, is characterised by more than two dwelling places in one household compound with mixed farming. Water is a serious problem in uMkhanyakude district. 70% of the farmers primarily used indigenous knowledge and acquired their skills on farming systems and practises from generation to generation indigenous knowledge system. In-field experiment was conducted. It was laid out in a randomized complete block design (RCBD) with three replicates having a net plot size of 3.6m x 5m. The following treatments were evaluated: Maize intercropped with beans (T1), Maize intercropped with pumpkins (T2), Maize intercropped with beans and pumpkins (T3), Maize sole crop control (T4), Beans sole crop control (T5), Pumpkins sole crop control (T6) and Bean intercropped with pumpkins (T7). Productivity was measured using the following indices: Land Equivalent Ratio (LER), Area Time Equivalent Ratio (ATER), Competition Ratio (CR), Relative Crowding Coefficient (K) and Aggressivity (A), Actual Yield Lost (AYL), Intercropping Advantage (IA) and Monetary Advantage Index (MAI). The study revealed that the intercropping system with three crop species in all three location showed greater values of LER (1.8, 1.9, and 1.7) and ATER (1.8, 1.9, 1.7). The crowding coefficient (K) was the highest in Mtubatuba and Hluhluwe treatment 3 (maize/bean/pumpkin) (80.72 and 61.78) respectively. Intercrops showed positive Agressivity, and greater competition ratio and actual yield loss when compared with the main crops. Intercropping advantage (IA) and monetary advantage (MAI) in treatment 3 (maize/bean/pumpkin in all locations showed greater values (58327, 12850, 5532) and (54573, 59487, 19606) respectively. The productivity of the intercropping system where there are more than two crops is considered greater in terms of land equivalent ratio (LER), area time equivalent ratio, (ATER).
Assessing the fertiliser value of co-composted biochar compost made from black soldier fly larvae faecal residue.
(2021) Nkomo, Nqobile.; Odindo, Alfred Oduor.; Missengue, Roland.
The Black Soldier Fly Larvae (BSFL) technology can treat faecal sludge emptied from full Urine Diverting Dry Toilets (UDDT’s). A residue containing residual mineral elements such as nitrogen (N), phosphorus (P), potassium (K), and high organic matter, pathogens, and potentially heavy metals is left behind. Improper disposal of the residue can pose a challenge and lead to environmental pollution and health threats. However, there is potential for recycling BSFL Residue. The fertiliser value of BSFL Residue as an organic fertiliser has not been studied in South Africa. This study was carried out to evaluate the use of co-composted biochar compost made from BSFL Residue as a plant nutrient source for maize production. The residue was pyrolysed for 120, 90, and 60 minutes at 300 °C, for 60 and 45 minutes at 400 °C, and 60, 45, and 30 minutes at 500 °C. Biochar pyrolysed at 300,400, and 500 °C for 60, 45, and 30 minutes, respectively, was not burned and was analysed for physico-chemical, and biological characteristics. Biochar yield decreased significantly with increasing pyrolysis temperature. Surface area, pH, extractable phosphorus (P), exchangeable bases, trace metals significantly increased with pyrolysis temperature. Pathogens were destroyed with pyrolysis. Biochar pyrolysed at 500 °C for 30 minutes was chosen based on its characteristics as a bulking agent in the co-composting experiment. Co-composting of the residue was carried out, and chemical and physical characteristics of BSFL Residue composts (COMBI (compost with biochar) and (COMP (compost without biochar)) were compared to chicken manure (CM) and BSFL Heated Residue (HR). pH and exchangeable bases in BSFL Residue COMBI were higher than BSFL Residue Compost but less than BSFL HR and CM. Composting with biochar significantly increased trace elements, water holding capacity, total P, and total N in the BSFL Residue COMBI compared to BSFL Residue Compost. The BSFL Residue COMBI, BSFL Residue COMP, BSFL Residue, HR, CM, Chemical Commercial Fertiliser (CCF), and control were incubated in a sandy Cartref soil over a 112-day incubation period to determine phosphorus and nitrogen release patterns. Phosphorus decreased in all treatments during the first 21 days except for the control. Phosphorus release started after day 21, and the pattern for BSFL Residue COMBI and BSFL residue Compost were comparable, indicating the potential of using these amendments for crop production. Chicken manure had the least phosphorus released at the end of the incubation. Ammonium decreased with a concomitant increase in nitrates for all treatments. Nitrate release was lower for BSFL Residue COMBI compared to BSFL Residue Compost. An additional source of N is needed if BSFL Residue COMBI is to be used as a fertiliser based on P. The highest nitrate release was observed in CM. Amendments used in the incubation were used at the recommended and double recommended application rate to grow maize in a greenhouse pot trial. Statistically similar yields were obtained in grain harvested from COMBI, COMP CCF, and CM. More researchshould be carried out on the residual effect of BSFL COMBI on subsequent maize growth to establish possible residual fertility on the second cycle of growth. Keywords: biochar; biochar co-compost; black soldier fly larvae;faecal matter; fertiliser-value; nutrient recycling; phosphorus; pyrolysis; crop growth.
Assessing the potential use of struvite and effluent from decentralized wastewater treatment systems (dewats) as plant nutrient sources for early maize ( zea mays) growth.
(2021) Sokhela, Fortunate Sthabile.; Odindo, Alfred Oduor.; Muchaonyerwa, Pardon.
The Decentralised Wastewater Treatment System (DEWATS) effluent has been shown to contain considerable concentrations of mineral elements such as nitrogen (N) and phosphorus (P), which are important for plant growth. The use of effluent for agriculture as a sole nutrient source is limiting in terms of macronutrient and micronutrient content supplied to plants. There is little information about the effects of combining the effluent with struvite and commercial fertilizer for crop production. The study aimed to determine the effect of applying struvite and DEWATS effluent as nutrient sources combined or in combination with urea/single superphosphate (SSP) fertilizers on the growth, nutrient uptake, and biomass production of maize. The specific objectives were: (1) to determine N and P release pattern of struvite when applied solely or combined with urea relative to SSP fertilizers combined with urea in a sandy soil, (2) to determine N and P release pattern of DEWATS effluent applied solely or combined with struvite and or SSP fertilizers in a sandy soil, (3) to investigate the effect of applying struvite and DEWATS effluent as nutrient sources combined together or with urea/SSP fertilizers on the growth, nutrient uptake and biomass production of maize. Two soil incubation experiments were set up under controlled room temperature at 25oC and 80% atmospheric humidity to determine the N and P release pattern of human excreta derived materials (HEDMs) (struvite and DEWATS effluent) with supplementary chemical fertilisers urea and SSP. The first experiment was laid out as a single factor analysis with the following treatments: (i) struvite alone, (ii) urea alone, (iii) SSP alone, (iv) struvite + urea, (v) SSP + urea. Each treatment was replicated 3 times to give 15 experimental units (in 5 litre ventilated containers). The second experiment was also laid out as a single factor comprising the following treatments: (i) effluent alone, (ii) struvite + effluent, (iii) effluent + SSP, and (iv) a control, all replicated 3 times to give 12 experimental units (in 5 litre ventilated containers). The fertiliser materials were applied to achieve an equivalent of 200 kg N/ha and 60 kg P/ha to meet maize nutrient requirements from the Cartref (sandy soil). The effluent in the study was applied as an irrigation source to achieve a 100% soil water holding capacity while supplying nutrients at the same time. Data was collected on the ammonium N, nitrate N, and extractable P release weekly, for 56 days. A pot trial was set up in 20 litre pots in the tunnel at 26oC air temperature and 65% atmospheric humidity to determine the effect of applying struvite and treated effluent from the anaerobic filters (AF) on growth, nutrient uptake, and biomass production of maize. The pot experiment was set up as a 9 x 2 factorial experiment in a completely randomised design (CRD) with the following treatments: fertilizer combinations (8 levels- (i) struvite + urea (recommended rates); (ii) ) struvite + urea (half recommended), (iii) struvite + effluent (recommended rates); (iv) struvite + effluent (half recommended); (v) SSP + effluent (recommended rates); (vi) SSP + effluent (half recommended); (vii) SSP + urea (recommended rates); (viii) SSP + urea (half recommended) and the control. The second treatment was maize variety with 2 levels –‘Colorado’ and ‘IMAS’. The treatments were replicated three times. Three maize seeds were planted per pot and were thinned 3 weeks after planting to one plant per pot. The amount of water applied as irrigation was based on Cartref soil water requirements. Soil moisture was maintained at 70-100% field capacity. The soil incubation experiment showed that there were significant (P<0.05) differences among treatments- struvite (S), effluent (E), SSP (P), urea (U), struvite + urea (SU), struvite + effluent (SE), effluent + SSP (PE), SSP + urea (PU) and zero fertilizer. The combination of HEDMs and commercial nutrient sources released higher ammonium-N and nitrate-N than sole applications and when commercial SSP + urea was applied together. Ammonium N declined over time and nitrate N increased rapidly over time. The findings suggested that the fertiliser combination of HEDMs and commercial fertiliser increased nutrient N availability to the soil. Phosphorus did not change over time in all treatments. The pot experiment result showed that there were significant (P<0.05) differences observed in plant height, leaf number, chlorophyll content, dry matter, N and P uptake, and grain + cob yields among the different fertiliser combinations (SE, SU, PE, PU) at both recommended and half recommended application rates. In conclusion, optimising N and P supply through a combination of the effluent and struvite or with inorganic fertilisers could potentially be considered as a better option for providing a balanced supply of nutrients than when applied separately.
Assessing variability in yield performance and nutritional quality of citron watermelon (citrullus lanatus var. citroides (L.H. Bailey) mansf. ex greb.) genotypes under drought conditions.
Mandizvo, Takudzwa.; Odindo, Alfred Oduor.; Mashilo, Jacob.
Research is needed to investigate the potential of Neglected Underutilized Crop Species (NUCS) such as citron watermelon, to increase crop diversity and mitigate the effects of prolonged drought because of climate change. Little is known about citron watermelon’s food quality attributes (seed popping yield, nutritional value, and lignin content). In addition, there is a need to understand the agro-morphological, physiological and biochemical characteristics associated with drought tolerance in citron watermelon. Therefore, the objectives of this study were: (1) to assess citron watermelon genotypes for food quality attributes (popping yield, chewability and nutritive value) of seeds based on visual appearance, (2) to screen citron watermelon accessions for drought tolerance using morphological and physiological traits, (3) to study the root system architecture of citron watermelon accessions and identify droughtadaptive root traits for cultivar improvement under water-stressed environments and (4) to reveal how citron watermelon responds to combined stress (water deficit and high temperature) with respect to growth, water status, reserve mobilization and metabolite partitioning at seedling stage. The first study determined whether citron watermelon seed’s nutrient composition and physical properties are related to the visual appearance of seed coat. Brown and red-coloured seeds have a higher popping yield than dark-coloured seeds with poor popping ability and are prone to burning during roasting. Seed coat thickness was closely related to hemicellulose contents and cellulose across all seed coat colours. High hemicellulose, cellulose and lignin contents were found in dark and red seeds associated with thick seed coats and increased chewing strength than white seeds. From a nutritional perspective, dark and red seeds were good sources of Cu, Zn, nitrogen and sulfur than brown seeds. Dark and brown seeds were good Mg sources, whereas dark and red seeds were vital sources of potassium. The second study determined variation in drought tolerance among South African citron watermelon landrace accessions for selection and use as genetic stock for drought-tolerance breeding in this crop and closely related cucurbit crops such as sweet watermelon. The forty citron watermelon accessions evaluated showed varying levels of drought tolerance based on morphological and physiological traits. These allowed five distinct groupings, namely: A (highly drought-tolerant), B (drought-tolerant), C (moderately drought tolerant), D (droughtsensitive) and E (highly drought-sensitive) based on various drought tolerance indices. The following accessions (WWM02, WWM-05, WWM-09, WWM-15, WWM-37(2), WWM-39, WWM-41 (A), WWM-46, WWM-47, WWM-57, WWM-64, WWM-66, WWM-68 and WWM-79) were categorized as highly-drought tolerant and accessions WWM-03, WWM-08, WWM-14, WWM-21, WWM-33, WWM-35(1), WWM-35(2), WWM-67 and WWM-76 as drought tolerant. These are useful genetic stocks for improving drought tolerance in this crop and related cucurbit crops, including sweet watermelon. The third study examined citron watermelon accessions’ root system architecture and identified drought-adaptive root traits for cultivar improvement under water-stressed environments. The study showed that plasticity and biomass allocation shift according to genotype, presumably to optimise the use of limited resources. The study found significant phenotypic variation in root architecture among citron watermelon accessions that may relate to differences in water uptake. The following traits of root system architecture (RSA) (total root length, root system width, convex hull area and total root volume) were associated with drought tolerance. Further, RSA traits such as root dry mass and root shoot mass ratio were highly correlated with root branch count, root system depth, total root length and leaf number. These traits are useful selection criteria for breeding and developing water-efficient citron watermelon accessions for cultivation in drought-prone environments. The fourth study identified multiple abiotic stress-induced modifications in different phytosterols (campesterol, sitosterol and stigmasterol) in the seedling axis (embryonic leaf and root) of genetically distinct citron watermelon accessions. Detailed evaluation of phytosterols was done and the effects of the changes observed in stressed plants were discussed.
Assessment of sweet sorghum lines for genetic diversity using quantitative traits and SSR markers.
(2016) Chinyama, Sombo.; Sibiya, Julia.; Odindo, Alfred Oduor.
The increase in energy demand, volatile oil prices and climate change has led South Africa to reduce its dependency on fossil fuels and promote biofuels. Sweet sorghum [Sorghum bicolor (L.) Moench] has been considered as one of the promising crops due to its sugar-rich stalk to supplement sugarcane which is the major feedstock for bioethanol. Establishing genotypic variability for biomass yield and sugar-related traits in sweet sorghum is therefore essential for developing superior cultivars. The objectives of the study were: (i) to assess sweet sorghum lines for agronomic performance and genetic diversity using quantitative morphological traits and (ii) to assess sweet sorghum lines for genetic diversity and interrelationships using simple sequence repeat (SSR) markers. Twenty-five sweet sorghum lines collected from International Crops Research Institute for the Semi-Arid Tropics (ICRISAT-Kenya) and the African Centre for Crop Improvement (ACCI-South Africa) were evaluated during the 2015/2016 season in KwaZulu-Natal (KZN) province at Ukulinga Research Farm in Pietermaritzburg and Makhathini Research Station in Jozini. Seven agronomic traits; fresh biomass yield, fresh stalk yield, grain yield, plant height, stalk diameter, panicle length and days to 50% flowering, and six quality traits; fibre, dry matter, °brix, °total brix, total fermentable sugars and ethanol were recorded. The sweet sorghum lines revealed highly significant variations for the 13 quantitative characters assessed in this study. The extent of variation was highly influenced by environment and genotype by environment interaction. Genotypes designated as IS 2331, IESV 92008 DL, ICSV 700, AS 244, URJA and SS 27 were identified as suitable genotypes with high plant height, dry matter, fibre, °brix, °total brix, total fermentable sugars and ethanol. The specified genotypes also exhibited medium to late maturity with relatively high fresh biomass and fresh stalk yield. Genotype 91018 LT showed the highest fresh biomass yield, fresh stalk yield, stalk diameter and relatively high grain yield. High levels of trait heritability were observed for fresh stalk yield (98%), stalk diameter (93%), fresh biomass yield (81%), panicle length (76%), fibre (73%) and plant height (66%). Heritability estimates were influenced by the environment and genotype by environment interaction. Principal component analysis resulted in the first three principal components showing 83% of the total variability among the genotypes. Ethanol, total fermentable sugars, °total brix, fresh stalk yield and °brix contributed mainly to PC 1, whereas fresh biomass yield and stalk diameter contributed mainly to PC 2. The dendrogram generated from cluster analysis divided the genotypes into two main clusters and three singletons (ICSB 324, ICSB 654 and ICSV 700). Cluster I comprised 54% of the total germplasm and included only one ACCI genotype (SS 27), while cluster II comprised of 33% of the total variation. The morphological variability analysis of the genotypes was also complimented with the use of molecular markers. The 24 sweet sorghum lines were genotyped with 10 simple sequence repeat (SSR) markers and distance-based method was used to analyze the data. Variation was observed for all the markers with allelic size ranging from 1 to 36 bp. A total of 61 alleles were generated with an average of 6.1 alleles per locus. The polymorphism information content (PIC) values ranged from 0.32 to 0.86 with an overall mean value of 0.62, showing a high discriminating ability of the markers used. The largest genetic distance was observed for AS 244 (GD = 1.9), while IESV 92001 DL and IESV 92008 had the smallest genetic distance (GD = 0.50). The dendrogram generated from cluster analysis using SSR markers classified the 24 sweet sorghum lines into two major clusters. Cluster I comprised of 12.5% of the total genotypes which included URJA, SS 27 and ICSB 654. It was observed that all ACCI genotypes apart from AS 244 were grouped in Cluster I, with URJA and SS 27 being very closely related. Cluster II was observed to be the largest (87.5%) with 21 genotypes, which further formed 3 sub-clusters (A, B and C) and a singleton (AS 244). The results from molecular marker characterization were similar to those obtained using PCA analysis of morphological traits which grouped genotypes into four clusters, with the same type of genotypes in each group. The information obtained in this study coupled with phenotypic characterization can be used by plant breeders to select parents or pure lines that can be used in developing improved cultivars. This will therefore contribute to the production of sweet sorghum and promotion of its use for bioethanol in South Africa.
Characterisation of cowpea accessions based on agro-morphological traits, nutritional quality and molecular markers.
(2017) Ringo, Goodluck Douglass.; Sibiya, Julia.; Odindo, Alfred Oduor.
Abstract available in PDF file.
Chemical mutagenesis of wheat for herbicide resistance.
(2012) Ndou, Vuledzani Nico.; Shimelis, Hussein Ali.; Odindo, Alfred Oduor.
Weed infestation is one of the yield limiting factors in crop production. Weeds have negative effect on crop growth and productivity due to competition, allelopathy or hosting other harmful organisms. For large-scale wheat production, the use of wide spectrum pre-emergence or post-emergence herbicides remains the most valuable weed control tool. In South Africa, annual grass weeds are a major wheat production constraint, which is usually managed through application of pre-emergence herbicides. Due to limited water availability and low soil moisture content, these herbicides can often become ineffective and result into high weed infestations, which then have to be managed by manual cultivation or post-emergence herbicidal applications. However, there are no effective selective post-emergence herbicides available to control grass weeds in wheat. There is also limited option to use broad-spectrum post-emergent herbicides because they non-selectively kill the crop and weeds. Consequently, the use of herbicide resistant crops is a viable weed management system in wheat production. Breeding herbicide resistant crop varieties would allow farmers to safely use post-emergence herbicides without damaging the crop. Subsequently yield and quality losses will be reduced significantly. Thus, the development of herbicide resistant crop varieties through mutation breeding is a novel approach for effective weed management under both small-scale and commercial farmers. Mutagenesis has been recognized as one of the most efficient method to induce genetic variation in plants. Through induced mutations, development of new variants is possible that could be manipulated in plant breeding programs. Mutation leads to alteration of various traits in crop plants including plant height, improved nutritional quality, shorter growing period, increased tolerance or resistance to abiotic and biotic stresses. Ethylmethanesulphonate (EMS) is one of the most widely used chemical mutagens to induce mutagenesis in crop plants. The objectives of this study were to: 1) determine the optimum EMS concentration, treatment temperature and duration that would provide desired germination percentage and vigorous and healthy seedlings for effective mutagenesis in wheat, 2) investigate variations in agro-morphological traits in two selected wheat varieties (SST56 and SST875) after EMS mutagenesis and 3) select herbicide resistant wheat germplasm after inducing genetic variation using EMS using two selected wheat varieties (SST56 and SST875). The objectives were achieved through three independent studies as outlined below: In the first study seeds of four selected wheat varieties (B936, B966, SST387 and SST875) were treated in two replicates with three EMS concentrations (0.3, 0.5, and 0.7%), three temperature regimes (30, 32.5 and 35 °C) at four time durations (0.5, 1, 1.5 and 2 hrs). Results showed highly significant interactions (P<0.01) among varieties, EMS concentrations, temperature and exposure time on seedling emergence, germination and seedling height. Seeds treated with the highest EMS dose (0.7%), temperature (35ºC) and long exposure time (2 hr) showed delayed emergence by 18 days. At 30ºC, 0.5hr and 0.3% EMS varieties B936, B966 and SST875 had early emergence (6 days). B936 and SST387 had 50% while B966 and SST875 had 53% and 57% germination, respectively. These results were observed at EMS level of 0.7%, 300C and 1.5 hr exposure time in B936 and EMS at 0.5%, 350C and 1.5 hr in B966. SST387 and SST875 required EMS dose at 0.5%, 32.50C and 2 hr treatment time. Other low or high treatment combinations were invariably ineffective comparedto untreated control. During the second study two selected varieties (SST56 and SST875) were subjected to EMS mutagenesis using 0.5% v/v EMS at 32.5oC for 1 hr. Field trials were carried out at Ukulinga research farm of the University of KwaZulu-Natal in the randomized complete block design with two replicates. Data on nine important agro-morphological traits were collected and analyzed using the analysis of variance (ANOVA), correlation and principal component analysis (PCA) procedures. Significant variations were found among the agro-morphological traits between M1 individuals compared to untreated checks. The mutagenesis significantly reduced seed germination in the field at 40% in both varieties. The treatment significantly delayed days to heading by 8 days and shortened days to maturity by 13 days in both varieties. EMS treatment also significantly reduced plant height at 18 cm in SST56 and 21 cm in SST875 and spike length reduced by ~2.5 cm in both varieties. Plant height had positive and significant correlation with number of tillers, number of seeds per spike, flag leaf length and 100 seed weight. However, it had negative correlation with the number of days to maturity. The PCA revealed that three principal components (PC1, PC2 and PC3) accounted to 57% of the total variations among the agro-morphological traits in both varieties. PC1 alone contributed to 27.7% of the variation which was well-correlated with plant height (0.767), tiller number (0.812), number of seeds per spike (0.599) and seed yield (0.720). PC2 explained 15.6% of the variation and well-correlated with germination percentage (0.784), spike length (0.554) and flag leaf length (0.772). PC3 accounted to 12.4% of the variation and had negative correlation with days to maturity (-0.730). In the last study, seeds of two selected wheat varieties (SST56 and SST875) were treated with EMS at 0.5% concentration for 2 hr at 32.5ºC. Treated seeds and comparative controls were planted at the experimental farm of the University of KwaZulu-Natal using the randomized complete block design. Four weeks after planting M1 plants and untreated standard checks were sprayed with two herbicides, i.e. metsulfuron-methyl and bromoxynil at three different doses viz. 2x, 4x and 8x above the recommended rate of 4 g ha-1 and 2 kg ha-1, respectively. Two weeks after the treatment herbicide resistance were assessed. Results showed significant difference among varieties, tested herbicides and doses used. The EMS treated wheat lines showed variable degree of herbicide resistance compared to untreated controls. Overall, the study established the requirement of variety specific EMS dose and treatment temperature and duration that could be used for inducing large-scale mutation to select targeted mutant individuals in wheat. Further, the study found that EMS has the potential to increase agro-morphological variations in wheat to select useful and novel mutants with desired phenotypic traits and herbicide resistance which will be subjected for further selections to identify stable and herbicide resistance lines.
Comparative analysis of two greenhouse microclimates in the sub-humid climate of South Africa.
(2014) Thipe, Ellen Letsogile.; Workneh, Tilahun Seyoum.; Odindo, Alfred Oduor.; Laing, Mark Delmege.
Development of small-scale greenhouse facilities that are suitable for the southern African agro-climatic conditions is one of the options that can be adopted to help alleviate food insecurity and malnutrition in Southern African countries. A comparative study was undertaken to analyse the temperature and relative humidity (RH) of two types of greenhouse tunnels, namely, the fan-pad evaporatively-cooled (FPVT) and the open-ended naturally-ventilated tunnels (NVT). The effect of the microclimates on crop growth, yield and quality, using tomatoes during the summer months and lettuce in winter, were also investigated. The effects of the integrated agro-technologies involving greenhouse microclimate and storage conditions on the postharvest quality of four tomato cultivars was also studied. The daytime temperature was lower in the FPVT than in the NVT during both summer and winter periods. Night-time temperatures were not significantly (P>0.05) different. The RH was higher in the FPVT than in the NVT, both during the day and at night. There was also a marked vertical and horizontal variation of temperature and relative humidity. Tomato vegetative growth was significantly (P<0.05) higher in the FPVT, but there were no significant (P>0.05) differences in the total yield and the total marketable yield of tomatoes grown in the FPVT and the NVT. However, the total yield was 24% higher in the NVT, but the total marketable yield was 8.3% higher in the FPVT. Highly significant (P<0.01) cultivar differences were observed, with Bona performing the best in terms of total yield and total marketable yield under both NVT and FPVT microclimates. During winter, there were no significant (P>0.05) differences in the growth and yield of lettuce crops resulting from the effect of the microclimate, although there was a higher incidence (by 26.9%) of leaf tip-burn in the FPVT. Between the two lettuce cultivars, growth was faster and the yield was 11.5% higher for Ballerina than for Nadine. However, Ballerina also had 24 to 29.6% more leaf tip-burnt leaves than Nadine. The integrated agro-technology study involving pre-harvest and postharvest treatments, which included the effect of greenhouse microclimate and postharvest storage environmental conditions on the texture, colour, TSS and pH of the four tomato cultivars, had significant (P>0.05) effects. NVT-grown tomatoes had and retained a firmer texture (by 7.4%) for a longer period, had a higher TSS value (by 10.3%), but a more rapid colour change, from mature-green to red-ripe, than FPVT tomatoes. Among the four tomato cultivars, Bona was the least firm and changed colour from green to red more rapidly, but it had the highest TSS and acidity than of the other three cultivars. With cold storage conditions at 13°C and 85% RH, the firmness of Bona was improved by 24.1% and the colour changes were reduced by 18.6%, compared to those under ambient air conditions (23± 2°C and 52± 4% RH). The cultivars Star 9037 and Star 9009 had the highest firmness and changed colour the least, but had the lowest TSS and highest pH values. This study has provided information about the microclimate of two types of greenhouses and their performance, in terms of the effects on growth, yield and quality of four tomato cultivars in summer and two lettuce cultivars in winter. The microclimate in the FPVT encouraged vegetative growth and improved the quality of the tomatoes. In the NVT, although the total yields were higher, the higher temperatures and insect/pests reduced the quality of the tomatoes. In winter, although the daytime temperatures were higher in the NVT, lettuce growth was not negatively affected, whereas in the FPVT, high humidity resulted in lower quality lettuce. The study also provided information on the integrated agro-technologies, involving greenhouse microclimate and postharvest storage environmental conditions on the postharvest quality attributes of tomatoes available on the South African market. NVT-grown tomatoes need cold postharvest storage, to reduce the ripening, in terms of colour, whereas FPVT grown tomatoes need cold postharvest storage conditions, in order to maintain a firmer texture for a longer period. It has also shown that the selection of the most suitable cultivar is important for profitable cultivation of vegetable crops in greenhouses. The study has further shown that small-scale naturally-ventilated greenhouses can be used for commercially-oriented agriculture to produce crops, with the aim to reduce poverty, create employment and address malnutrition. In addition, the study has shown that there is a need for further research aimed at reducing the daytime heat load of the greenhouses during the summer months, and the night-time heat loss during winter and a cost-benefit analysis, to establish the cost of production associated with the two tunnels. Furthermore, greenhouse microclimate research can be extended to the other South African climatic regions, to provide extensive information about the performance of these facilities and their effects on other greenhouse crops such as peppers and cucumbers.
Cowpea seed quality in response to production site and water stress.
(2007) Odindo, Alfred Oduor.; Modi, Albert Thembinkosi.; Southway, Colin.
Cowpea (Vigna unguiculata. L) is an important African crop. However, it is also an underutilized grain legume. Consequently, there is not enough research data on cowpea seed physiology. Whereas there is evidence of cowpea being a drought tolerant crop, there is no evidence to associate plant drought tolerance with seed quality in response to water stress. This study sought to understand the effect of production site and water stress on cowpea seed quality development with respect to germination capacity and vigour. Patterns of raffinose family of oligosaccharides (RFO) during seed development to mature dry stage were used to physiologically relate seed performance to water stress. The effect of water stress and exogenous ABA on the accumulation of stress LEA proteins (dehydrins) in relation to seed quality development and germination was investigated. RFOs are known for their roles in desiccation sensitivity but no studies have shown their significance in cowpeas. Seeds of six cowpea cultivars were produced at two distinct growth sites characterised by irrigated and dry land conditions. The seeds were assessed during six developmental stages, for water content, dry matter accumulation, and performance. Harvested seeds were then planted in a pot experiment under controlled conditions to examine the effect of water stress on seed quality development and data collected during three developmental stages. Harvested seeds from the pot experiment were subsequently analyzed for changes in RFO accumulation during development using gas chromatography. The seeds were also used to investigate the effect of water stress and ABA on the accumulation of stress LEA proteins (dehydrins) in relation to seed quality development in cowpea. In addition, this study evaluated the use of image analysis as a method that can be used to objectively determine seed coat colour variation in cowpea. Statistical variation in individual seed’s solute leakage for cowpea cultivars differing in seed coat colour and produced under different environmental conditions was explored and correlations were done between seed conductivity test with other aspects of seed performance during germination. Furthermore the results of the conductivity test were compared with accelerated aging test, in relation to seed performance. The study provided evidence that cowpea seed lots produced under different environmental, and possibly management conditions may not differ with respect to seed quality as determined by germination capacity and vigour. However, significant differences between sites with respect to seed maturation patterns determined by water content and dry matter accumulation were observed. Adverse maternal environmental effects on the subsequent performance of seeds in a drought tolerant crop may not necessarily lead to poor performance. Cultivar differences in response to simulated drought conditions at the whole plant and tissue level can be considerable and highly variable; however, these differences may not have adverse effects on the germination and vigour of the seeds. Drought avoidance mechanisms at the whole plant level in cowpea are quite efficient in allowing the species to adapt to simulated drought conditions. These mechanisms may allow the cowpea cultivars to maintain metabolism and restore conditions for their continued growth under water stress; and produce few seeds of high germination capacity and vigour. Stachyose was found to be the predominant member of the raffinose family of oligosaccharides in cowpea. It is suggested that stachyose accumulation could be used as an indicator of stress tolerance in cowpea. However, the relationship between RFO concentration and the acquisition of desiccation remained as a matter of speculation in the present study and is still generally inconclusive. There was no evidence to suggest the acquisition of maximum desiccation tolerance is associated with maximum seed vigour. It is suggested in cowpea, which is drought tolerant, that maximum vigour does not necessarily imply the acquisition of maximum desiccation tolerance; rather there is a minimum level of desiccation tolerance that is required for the development of optimal seed vigour. The use of an in vivo approach in the study of LEA function in cowpea enabled the accurate comparison of two different groups of LEA proteins in developing cowpea seeds under conditions of water stress and in relation to germination and vigour. Both group 1 LEA and group 2 LEA (dehydrin) were shown to increase in concentration in response to water stress. In addition group 1 LEA protein was observed to be relatively abundant in cowpea seeds. A maternal influence on LEA protein gene expression under conditions of water stress, which may induce dehydrin accumulation vii during the earlier stages of seed development, was implied by the observation that dehydrin-like proteins were induced after two weeks of development in cowpea plants subjected to stress during the vegetative phase. In addition, the exogenous application of ABA delayed radicle protrusion; this was associated with a delay in the disappearance of LEA proteins and is suggestive of a relationship between LEA protein accumulation and the acquisition of desiccation tolerance. The study has demonstrated that image analysis can objectively discriminate seed coat colour variation in cowpea. Dark coloured seeds in general performed better than light coloured seeds; however seed coat colour was not always associated with better performance. A newly developed Aging Stress Differential Index (ASDI) has been used in this study to demonstrate a link between seed coat colour and sensitivity to water stress. The ASDI correlated well with the observations relating stress tolerance to stachyose accumulation. The skewed distribution patterns in individual electrical conductivity and the presence of extreme values may have implications with respect to the suitability of using standard statistical analyses which compare mean values to evaluate such data. In addition variation in individual electrical conductivity may also be influenced by cultivar differences and the chemical composition of the seed coat. Therefore associations between seed coat colour and electrical conductivity as a measure of performance should be treated with caution. The AA test does reflect changes in seed vigour, however ranked electrical conductivity values after AA did not consistently reflect differences in seed performance between cultivars and sites, and they did not correlate well with other aspects of performance.
Crop fertigation (nitrogen and phosphorus) with decentralised wastewater treatrment system effluents and effects on soil and groundwater.
(2018) Musazura, William.; Odindo, Alfred Oduor.; Buckley, Christopher Andrew.; Hughes, Jeffrey Charles.; Tesfamariam, Eyob Habte.
Urbanisation is contributing to increased informal settlements in peri-urban areas and municipalities are facing challenges in providing sanitation. The decentralised wastewater treatment system (DEWATS) is a low cost, water-borne, onsite sanitation technology that can potentially serve peri-urban areas. The DEWATS treats human excreta to produce effluent that contains mineral nutrients, especially nitrogen (N) and phosphorus (P). Discharging treated wastewater into water bodies may cause pollution. Considering water scarcity, poverty and hunger issues in most developing countries, reuse of treated wastewater in agriculture promotes sustainable development if done in an environmentally friendly manner. This study therefore aimed at understanding the effects on crops, soils and the environment of fertigating with DEWATS effluent. All the studies were conducted at Newlands-Mashu experimental site (30°57’E, 29°58'S), Durban, South Africa. A field experiment investigated the effects of DEWATS effluent on tissue cultured banana (Musa paradisiaca var Williams) and taro (Caucasia esculenta). The study was carried out in a randomised complete block design with two irrigation treatments (DEWATS effluent without fertiliser vs tap water + fertiliser). Two crops were grown in an intercrop over two cropping cycles using drip irrigation. Two sources of effluent from the DEWATS were used. Effluent after treatment through a horizontal flow constructed wetland (HFCW) was used during the first cropping cycle and anaerobic filter effluent (AF) was used in the second cropping cycle. Data was collected on soil leachates, soil chemical properties, water table level, crop growth, yield and nutrient uptake, with a focus on N and P. Fertigation with DEWATS significantly (p < 0.05) increased taro growth during the first cropping cycle. No significant differences (p > 0.05) were reported for crop yield, N and P uptake and leaching between treatments showing its potential to substitute for inorganic fertilisers. The AF effluent significantly (p > 0.05) increased soil inorganic N in the 0.3 m soil depth (rooting zone) after the second cropping cycle thereby acting as important N fertiliser source. Based on the findings no water table hazards due to low deep percolation and subsurface lateral flow was detected. However, subsurface drainage must be constructed in areas where water table rises to prevent groundwater pollution. A pot experiment was conducted to investigate fertigation of banana using DEWATS effluent on three different soil types. A factorial study was conducted in a complete randomised design. The treatments were three soil types (Inanda (Ia); Rhodic Hapludox / acidic clay soil, Sepane (Se); Aquic Haplustalf / clay loam soil and Cartref (Cf); Typic Haplaquept / sandy loam soil) * two irrigation sources (DEWATS effluent vs tap water + fertiliser) * four replicates. The Ia soil was collected from Worlds View, Pietermaritzburg (29°35′S, 30°19′E), the Cf soil from KwaDinabakubo, Hillcrest (29°44’S; 30°51’E) and the Se was from the field trial site at Newlands-Mashu. Soils for the tap water + fertiliser treatment were mixed with inorganic fertilisers based on recommended crop requirements before being packed in a 90 L pot. The study was carried out over 728 days and all soils were irrigated to field capacity. Data was collected on banana growth (total leaf area and plant height), yield, N and P uptake and leaching, and soil chemical properties. Use of DEWATS effluent significantly (p < 0.05) increased banana growth and yield in the Cf soil thereby showing ability of effluent to improve productivity in nutrient deprived soils. The NH4+-N and P concentrations significantly increased in all DEWATS effluent fertigated soils. Therefore, the effluent is a source of fertiliser that can potentially be used in place of conventional inorganic fertilisers. The N leached from the DEWATS treatment was significantly (p < 0.05) lower than from the tap water + fertiliser treatment hence its use is environmentally sustainable. In all soils fertigated with DEWATS effluent, N leaching was significantly high in Ia soil hence fertigation in such a soil needs proper scheduling. The soil water balance (SWB-Sci) model was used to simulate water, and N and P dynamics in DEWATS effluent fertigated soil. The model was calibrated and validated based on data collected in the field studies. The crop growth model was successfully validated as it met all the standard statistical criteria required (i.e. r2 > 0.8, MAE < 20 % and D > 0.8). High concentrations of inorganic N and P in topsoil fertigated with DEWATS effluent were simulated. Nitrate leaching was comparably higher in DEWATS effluent fertigated soils but without significant impact on ground water contamination in the respective soil. Therefore, the use of DEWATS effluent in clay soils is sustainable. The calculated land area required to fertigate banana and taro in an intercrop using effluent from each DEWATS was 117 m2·household-1 (23.3 m2·person-1). If banana is grown as a sole crop land requirement could have been Cf (290 m2 household-1; 58 m2 person-1), Ia (260 m2 household-1; 52 m2 person-1) and Se (200 m2household-1; 40 m2 person). Based on these findings it can be concluded that DEWATS effluent increases crop growth, yield, nutrient uptake and soil inorganic N and P within the rooting zone like more conventional practices. On-farm irrigation management practices such as scheduling with room for rainfall helps to prevent N and P leaching and rising water table. The SWB-Sci model is an irrigation scheduling and nutrient (N and P) management tool which may be used by decision makers and local governments in producing practical guidelines for sustainable wastewater use projects.
Dormancy breaking methods and priming techniques to improve seed germination in gynandropsis gynandra (L.) briq syn cleome gynandra L. (Cleomaceae).
(2022) Mangena, Khungeka.; Odindo, Alfred Oduor.
Gynandropsis gynandra, commonly known as spider plant, is a leafy vegetable that belongs to the Cleomaeae family. Spider plant is used for its medicinal properties, but also as a nutritional supplement, and an animal (e.g., cows) feed. Farmers experience low and uneven germination when planting this species that studies ascribed to physiological dormancy which leads to low and uneven germination. The study was conducted to understand mechanisms involved in breaking dormancy in spider plant seeds. The objectives were (a) to determine the effects of packaging materials and storage period on seed germination, and (b) to determine the effects of priming agents and duration on seed germination of G. gynandra. These objectives were achieved through two experiments based on six accessions of G. gynandra originated from West Africa, East Africa, and Asia. In the first experiment, the seeds were stored for four months at room temperature of 25℃ in brown paper bags, aluminium foil paper, and black polystyrene bags. After every storage period, the seeds were tested for electrical conductivity (EC), viability using tetrazolium chloride and germination ability to study the effects of storage period and packaging material on seed viability and vigor of G. gynandra. In the second experiment, the six accessions were subjected to two priming agents, PEG-4000, and distilled water, and tested for germination. Final germination percentage (FGP), mean germination time (MGT), mean germination rate (MGR), coefficient of the velocity of germination (CVG), and radicle length (RL) were recorded. Data analysis was done using Genestat version 20th edition (VSN International, United Kingdom) at a 5% level of significance. The study showed that G. gynandra fresh seeds displayed physiological dormancy which can be broken by storing seeds for at least two months depending on the genotype in aluminium foil paper. In this study, seed priming with PEG-4000 and distilled water had no effect on seed germination of G. gynandra.
Effect of ABR effluent irrigation on Swiss chard (Beta vulgaris subsp. cicla) growth and nutrient leaching.
Musazura, William.; Odindo, Alfred Oduor.; Tesfamariam, Eyob Habte.
The Decentralised Waste Water Treatment System (DEWATS) is used in countries such as India and Indonesia for the treatment of human waste. The waste is passed through a series of baffles where it is anaerobically degraded, resulting in the production of the Anaerobic Baffled Reactor (ABR) effluent. Disposal of the effluent can still pose a challenge if not done properly and lead to environmental pollution. The effluent has been shown to contain high concentrations of mineral elements such as nitrogen and phosphorus, which are important for plant growth. There is little information on the use of effluent for agriculture particularly under the South African climatic and edaphic conditions. This study investigated the effect of using ABR effluent on the nutrient uptake, growth and yield of Swiss chard (Beta vulgaris subsp. cicla) on selected soil types. Field and tunnel experiments were carried out at Newlands Mashu Permaculture Centre in Durban (longitude of 30°57'E and latitude of 29°58'S). The initial experiment planted in the summer season of 2012 was designed to collect baseline data on growth and yield of Swiss chard and other selected crops under rain-fed vs. irrigated conditions using tap water. The treatments were laid out using a randomised complete block design (RCBD) with three replications. The treatments included: tap water irrigation without fertiliser application (TW); tap water irrigation with fertiliser application (TWF) and rain-fed with fertiliser application (RFF). The second experiment was conducted in winter 2012 with the aim of investigating growth and yield of Swiss chard irrigated with ABR effluent during the dry season. In the second study, the treatment “tap water irrigation without fertiliser application” was substituted with irrigation with ABR effluent while the other treatments were maintained. The third experiment was conducted in the summer season of 2013. The treatments remained similar to those of the winter 2012. Soil samples were collected from the top 30 cm before planting and after harvesting for chemical analyses. A neutron probe access tube was also installed in the middle of each plot in order to monitor soil water status and irrigate plots according to the root zone soil water deficit. Wetting Front Detectors (WFDs) were installed at 30 cm and 50 cm depths to monitor nutrient leaching. The leachates collected by WFDs were analysed for nitrates and phosphates using Merck Reflectoquant test kit. Similarly, the ABR was analysed for its chemical composition before each irrigation event. Treatment effect on Swiss chard and soil was tested by analysing fresh crop biomass, dry biomass, chlorophyll content, crop nutrient uptake and soil chemical properties. Parallel studies were conducted in a tunnel to investigate growth and yield response of Swiss chard grown on different soils (acidic, clayey loam and sandy loam soil) treated with varying fertiliser rates. The experiment was laid out as a factorial treatment structure with the following factors: Irrigation source (2 levels); soil type (acidic, clayey loam and sandy loam soil) and fertiliser application rate (No fertiliser, half-optimum recommended rate and optimum recommended rate based on soil analyses) replicated four times. The Swiss chard was grown in the tunnel in pots for 11 weeks. Crop growth and chlorophyll data, similar to that collected from the field was also collected from the pot trials. Data analysis was done using GenStat® 14th Edition (VSN International, Hemel Hempstead, UK). The results from the baseline study (experiment 1) did not reveal significant differences between treatments (TW, TWF and RFF) thus suggesting that the inherent soil fertility was high and could support Swiss chard growth. There were significant differences (P<0.05) between the treatments (ABR, TWF and RFF) during the winter season (experiment 2) with respect to Swiss chard biomass. Swiss chard plants produced under rain-fed conditions had lower dry mass compared with those that were irrigated using ABR effluent and tap water with fertiliser. However, the effect of using ABR effluent on Swiss chard biomass was comparable to tap water with fertiliser because these did not differ significantly. The results from the third experiment showed a lack of significant differences with respect to N and P leaching between the irrigation sources (ABR, TWF and RFF). Controlled experiments in the tunnel revealed a significant interaction between soil type and irrigation source. Swiss chard pots containing acidic soil and irrigated using the effluent showed significantly higher dry mass (P < 0.01), fresh mass (P< 0.05) and leaf area index (P < 0.001) compared to those irrigated with tap water. In conclusion the ABR effluent may have a liming effect which could have possibly increased Swiss chard growth in acidic soil. ABR effluent was more useful as an irrigation source in winter than in summer; however in summer the effluent could be more useful as a fertiliser source in areas where water is not limiting for crop production. N and P leaching and uptake could not be associated with irrigation using ABR effluent.
The effect of bioslurry, grass clippings and pumpkin live mulch on soil water content and maize production.
(2016) Ngubo, Nelile.; Odindo, Alfred Oduor.; Everson, Theresa Mary.
Abstract available in PDF file.
The effect of ethylmethanesulfonate (EMS) on morphological characteristics and seed quality development of Vernonia (Centrapalus pauciflorus var.ethiopica Willd.)
(2015) Boyanee, Andre Bwandola.; Odindo, Alfred Oduor.
Vernonia (Centrapalus pauciflorus Willd.) belongs to the Asteraceae family (Compositae). The crop can produce epoxidized vernolic acid oil that can be used by industries to produce products such as paints.Crop production is significantly hampered by non-uniform seed maturity, lodging due to tall plant height, seed shattering and lack of appropriate technologies. There is need for research to address these challenges and improve productivity. Firstly, this study compared two selected vernonia mutant lines (Vge-1 and Vge-4) and untreated controls with respect to morphological traits and seed quality development. A field experiment was conducted as a factorial design with 2 lines (Vge-1 and Vge-4) and 2 treatments (ethylmehanesulphonate treated and untreated seeds) at the University of KwaZulu- Natal Research farm at Ukulinga in Pietermaritzburg. The experiment was laid out in a Randomized Complete Block design (RCBD) with four replications, thus giving 16 experimental units (plots measuring 3mx6m). Data was collected on plants height, leaf number of secondary heads, mass of heads per plant and yield. Highly significant differences (P<0.001) were observed with respect to leaf number and seed mass.Vge-1 mutants plant produced more leaves (48 leaves per plant) compared with untreated controls (40 leaves), Vge-4 treated seeds had higher mass of heads per plant (2.46g) compared untreated controls Vge-4 with (0.75g). Vge-4 had seed yields of 3.5 ton/ha compared with untreated controls (3ton/ha). The effect of EMS application on growth parameters in vernonia lines resulted in an increase in leaf number, mass of seed per heads and seed yield of Vge-4; this line could be important than Vge-1 for potential use of vernonia as a new industrial crop. Secondly, the study determined the pattern of seed quality development of Vge-1 and Vge-4 compared to untreated controls. Vernonia flowers were tagged at flowering stage and sampled at weekly intervals from seed development up to maturity. Twenty seeds from each line (both treated and untreated controls) at each developmental stage were used to determine solute leakage using conductivity meter (CM100). Percentage germination was determined using a growth chamber set at a constant temperature of 25oC. Samples of twenty seeds were used for determination of seed moisture content using Kett’s PM650 seed soil moisture meter (Kett instruments, USA). Viability tests were done using 2, 3, 4-triphenyl tetrazolium chloride (TZ) solution. Seed viability was evaluated by assessing the proportion of stained embryo according to the ISTA Rules and Methods for Seed Testing. Five seeds of each line (both treated and untreated controls) were scanned using an electron microscope to observe morphological changes during embryo development. The results showed that germination (%) was generally iv low but differed significantly (P<0.01) between the lines; Vge-1 untreated seeds had the highest germination percentage (60%) compared with Vge-1 treated with (58%). The low germination percentage in vernonia could probably be attributed to seed dormancy. Thirdly, the study investigated the effect of gibberellic acid (GA) and potassium nitrate on seed dormancy in vernonia lines. A total of 100 seeds per treatment (treated seeds of Vge-1 and Vge4 and untreated controls) were subjected to three different temperatures regimes (25/25°C; 25/17°C or 30/17°C) and 0.7mM gibberellic acid or 1mM KN03. Seeds germination was assessed on daily basis by recording seeds with a radicle protrusion of at least 2mm. Highly significant differences and interactions (P<0.001) were observed between temperatures and dormancy breaking chemicals with respect to percentage germination, mean germination time (MGT) and germination index (GI).The GI increased with GA3concentration application. The mean germination time (MGT) also improves for all treatments. Fourthly, the effect of EMS on seedling growth was investigated. Harvested seeds of the two lines Vge-1 and Vge-4 were soaked in 0.372%, 0.744% and 1.1% EMS solutions for 2 hours and rinsed in water for 30 minute. The experiment was laid out as 2x4x4x3 treatment structure using a completely randomized design with the following factors: Vernonia lines with 2levels (Vge-1 and Vge-4); EMS concentration 4 levels (0.372%, 0.744%, 1.1 % and control); duration time 4level (0.5, 1, 1.5 and 2 hour) and temperature 3 levels (30oC, 32.5oC and 35oC) replicated 3 times, giving a total of 96 treatments combinations and 288 experimental units. The treated seeds were sown in seedling trays filled with sterilized soil. The following data were collected; seedling emergence, seedling length, germination percentage and the presence of chlorophyll mutants. Highly significant differences (P<0.001) were observed between EMS treatments with respect to seedling vigor, germination percentage and seedling height. The seedling length decreased with increased EMS concentration. EMS concentration increased emergence percentage and germination index. Increasing EMS concentrations, temperature, exposure time and duration negatively affected on all the traits measured in the study. EMS had the effect of causing mutations as evidenced by the various chlorophyll mutants identified in the study. The major findings of this study suggest that EMS as mutagen was effective in inducing genetic variability in vernonia. This suggests that EMS can be used for creating new vernonia lines.
Effects of biochar addition on soil nitrogen retention and vegetable uptake in intensive production systems, China.
(2017) Yu, Ying Liang.; Odindo, Alfred Oduor.; Pillay, Balakrishna.; Yang, Linzhang.
China has a limited area of cultivated land per capita and an increasing population. Maintaining a high crop yield is essential to meet the large food demand and to assure grain self-sufficiency. With the pace of economic development, the demand for vegetables keeps growing. In Southern China, many of the fields used to grow vegetables were previously under paddy production. Compared to the paddy production system, the vegetable production system is intensive with excessive use of nitrogen fertilizer. Excessive nitrogen fertilizer application has changed soil chemical properties and nutrient dynamics, and thus created a negative impact on sustainable agricultural development. A preliminary study was conducted in the absence of nitrogen fertilizer to determine the effect of field utilization conversion on soil nitrogen uptake by pakchoi. It was found that soil pH values and organic matter content decreased with intensive vegetable planting and nitrogen leaching loss was higher from vegetable soils compared to that from paddy soils. Although the soil mineral nitrogen content in vegetable soils was higher than that in paddy soils, nitrogen uptake by plants from vegetable soils was lower than that from paddy soils, and decreased quickly in the later growing seasons. The lower plant nitrogen uptake was attributed to the high nitrogen leaching loss and soil acidity caused by the excessive application of nitrogen fertilizer in vegetable production systems. Therefore, it is imperative to find suitable approaches to mitigate nitrogen leaching loss and soil acidity in vegetable production systems and promote nitrogen retention and vegetable nitrogen uptake for sustainable productivity. Biochar is a fine-grained and porous substance produced through pyrolysis processes, under oxygen-free conditions, from a wide range of biomass. In recent years, biochar has received more attention with regard to its capacity to increase crop yields by ameliorating the soil environment and regulating nutrient processes. According to previous studies, biochar is an option for mitigating soil acidity and nitrogen leaching problems in vegetable soils due to its alkalinity and adsorption properties. However, studies of biochar addition to vegetable production systems have not been well documented. The effect of biochar addition on leachate volume is still lacking. Whether the mineral nitrogen retained by biochar can be re-used by plants is still unknown. Few studies have investigated the effect of biochar addition on nitrogen processes and soil acidity under continuous growing conditions. Therefore, with the aim of determining the effect of biochar on soil nitrogen retention and vegetable nitrogen uptake, pakchoi was planted in a pot experiment during four continuous growing seasons with three biochar addition rates (0, 1% w/w and 5% w/w). In the 1st, 2nd and 3rd seasons, pakchoi was applied with 15N-labelled urea and in the 4th season no nitrogen fertilizer was provided. The results of this study were presented in four parts (soil nitrogen retention, soil acidity, vegetable nitrogen uptake and a distinction between two nitrogen sources in vegetable nitrogen uptake i.e. nitrogen left in the soil and nitrogen loss). The main conclusions are as follows: Biochar addition significantly increased the soil mineral nitrogen content by enhancing nitrogen retention in soils and soil nitrogen mineralization. Part of the mineral nitrogen retained by biochar was still bioavailable for plant uptake in the soil. Biochar significantly reduced nitrogen leaching loss by decreasing leachate volumes and nitrate concentrations in the leachate. Biochar addition significantly ameliorated or retarded soil acidity by promoting soil pH buffering capacity, reducing soil acidification rates and maintaining soil bases contents induced by biochar. The mitigation of soil acidity was not only as a result of biochar’s natural alkalinity but can also be attributed to the altered nitrogen processes (promotion of plant nitrate uptake, reduction of nitrification and nitrate leaching and maintaining soil bases contents) with the addition of biochar. Biochar’s mitigation of soil acidity was partly dependent on its effect on soil properties (such as bases contents) and processes (such as nitrification, nitrate leaching and plant nitrate uptake) rather than its natural alkalinity. Biochar maintained pakchoi yields and nitrogen uptake during four growing seasons. The fertilizer nitrogen recovery efficency was improved with an increase in the recovery of fertilizer nitrogen in the soil and the decrease in the recovery of fertilizer nitrogen in leachate. Fertilizer nitrogen was the major source for pakchoi nitrogen uptake, soil residual nitrogen and nitrogen leaching loss, while nitrogen from soil mineralization was the major nitrogen source for biochar retention. When nitrogen fertilizer was absent in the 4th season, the nitrogen fertilizer left in the soil from the 1st to 3rd seasons decreased sharply and fertilizer nitrogen retained by biochar was simultaneously released. The conclusion was that biochar addition could promote soil nitrogen retention and maintain high nitrogen uptake by vegetables in continuous growing seasons. However, the comprehensive effect of biochar on nitrogen loss still needs to be assessed before recommending extended utilization of biochar in vegetable production systems in China.
Effects of organic and inorganic fertilisers on the growth of pseuderanthemum atropurpureum, soil fertility and leachate composition.
(2018) Constance, Duane Wayne.; Bertling, Isa.; Odindo, Alfred Oduor.
The use of fertilisers in agricultural production systems, particularly nitrogen and phosphorous, has been shown to be one of the causes of eutrophication as a result of the excessive enrichment of freshwater systems through surface runoff and soil infiltration. The contamination of freshwater bodies from horticultural production systems in South Africa has, however, been rarely studied, although influx from such systems are considered highly polluting elsewhere. Eutrophication is particularly considered a major problem in areas with limited water resources. Phosphate is especially limiting in contributing to eutrophication in South African rivers and dams. The development of harmful algal blooms, particularly from cyanobacteria, has been a concern for a long time due to toxins introduced into freshwater systems from these algae. This study investigated whether the use of organic fertilisers compared with inorganic fertilisers was potentially less detrimental to freshwater systems as a result of leachate nutrient and algal microorganism composition; further it was examined, if organic fertiliser was more beneficial to plant growth of Pseuderanthemum atropurpureum. Liquid and soluble granular organic and inorganic N equilibrated fertiliser treatments were applied at low, medium and high concentrations based on recommended label rates. Plant growth parameters were determined from mean height, number of leaves, size of leaves, number of nodes, internode length and number of branches. The species was grown over a period of three months and the experiment was repeated three times. Leaf tissue was analysed for mineral nutrient content and chlorophyll a, b and total chlorophyll. Leachate was analysed for mineral nutrient content including total phosphate, orthophosphate and chlorophyll a. Growth media was analysed for total nitrogen, ammonium and nitrate. A phase contrast light microscope was used to identify larger algal microorganisms and a scanning electron microscope (SEM) to identify smaller algal microorganisms from growth media extracted leachate. One specimen of green algae and some diatoms were identified, including two which may be found in eutrophic waters, but would not pose a threat similar to some species of cyanobacteria, if leached into freshwater systems over a period of time. Further, results showed that total phosphate and orthophosphate concentrations were significantly higher in leachate extracts from bark-based growth media across all fertiliser treatments and at all rates of treatment compared with soil-based growth media. This may have been due to a lack of binding sites in soilless media such as bark. Nitrate concentrations from organic soluble granular treatments were higher in both growth media types, whilst other treatments were similar. Ammonium and leachate nitrogen concentrations were found to be also similar. This may explain why plant growth traits assessed together were similar across all parameters tested. No single fertiliser compared with any other, produced plants that were superior in all growth characteristics measured. It is, therefore, suggested that the fertiliser treatments used in this study be applied at the half rate and plants be rather grown in randles growth medium than gromor for the production of Pseuderanthemum atropurpureum.
The effects of urine and urine-separated plant nutrient sources on growth and biomass production of perennial ryegrass (Lolium perenne. L)
(2015) Mchunu, Ntobeko.; Odindo, Alfred Oduor.; Bame, Irene Bongsiysi.; Muchaonyerwa, Pardon.
Urine contains plant essential nutrients, which may pose pollution problems if disposed of in the environment. Struvite is a concentrated phosphorus fertilizer produced by precipitation of Magnesium Ammonium Phosphate after addition of magnesium salts into urine. The struvite effluent has been shown to contain high concentrations of mineral elements such as nitrogen, which are important for plant growth. Urine can further be nitrified directly to produce a nutrient source with more of nitrate- N than ammonium- N. There is little information on use of these urine product for agriculture particularly in South Africa. The aim of this study was to determine the effect of urine and urine products, struvite (S), struvite effluent (S.E) and nitrified urine concentrate (NUC), on the growth and biomass production of perennial ryegrass. The specific objectives were (1) to determine nitrogen release pattern of urine and urine products (S, S.E and NUC) in two different soils (Cartref and Inanda soil), (2) to determine the effect of the application of urine and urine products on growth and biomass production of perennial ryegrass. A soil incubation experiment was set up under controlled room temperature at 25oC and 80% atmospheric humidity to determine nitrogen release pattern of urine and the urine products in two different soils. The experiment was designed as a 6 x 2 x 2 factorial treatment structure with five nutrient sources (urine, struvite effluent, struvite effluent + struvite, nitrified urine concentrate) and no fertilizer treatment as a control). The fertilizer materials were applied at two levels (recommended rates and double the recommended rates based on N rate). The two soil types used were the Inanda (acidic clay soil) and Cartref (sandy soil). The treatments were replicated three times giving 72 experimental units (in 2 kg ventilated containers). Data was collected on the ammonium and nitrate- N release on weekly basis for the period of 70 days. A pot trial was set up in 1 kg pots in the tunnel at 26oC air temperature and 65% atmospheric humidity to determine the effect of the application of urine and urine products on growth and biomass production of perennial ryegrass. The pot experiment was also designed as a 6 x 2 x 2 factorial treatment structure with six nutrient sources consisting of urine, struvite effluent, struvite effluent + struvite, nitrified urine concentrate and two controls; an inorganic fertilizer source (NPK 2:3:2) and no fertilizer treatment. The nutrient sources were either applied once off split applied three times. The fertilizer materials were applied at two levels (recommended rates and double the recommended rates) based on N rate. The treatment combinations were replicated three times. Plants were cut back to 5cm above the ground after attaining a cutting height of 20 cm height, and were allowed to regrow this was repeated four times. Soil moisture was maintained at 70-100% field capacity. The soil incubation experiment showed that there were significant (P<0.05) differences observed among treatments- U, S.E, S.E+S, NUC, NPK and Zero fertilizer, and among application rate. In Inanda soil, ammonium- N declined with incubation time while nitrate-N and mineral- N did not increase significantly. In the Catref soil ammonium- N declined with incubation time while nitrate- N and mineral- N increased significantly. The findings suggested that the Cartref soil released more nitrogen than Inanda soil hence it had more total mineral- N than Inanda soil Pot experiment result showed that there were significant (P<0.05) differences observed in dry matter production and plant height among the treatments, application method (once- off and split rate), application rates (recommended and double rate) and cuts (harvest), likewise in plant height. Dry matter production increased significantly with days after cuts- 1, 2 and 3 and it declined with time after cut 3 at cut 4. Split rate application method had significantly more dry matter than once- off application method. The recommended rate had significantly more dry matter than double rate. Treatment NUC responded significantly different within cuts. NUC treatment at recommended had significantly higher dry matter yield then all treatments at cut 1 and 3. At the same time there were no significant differences in dry matter production between NPK and urine and urine products. All treatments had however significantly higher dry matter than zero fertilizer treatment. The findings of the study suggested that urine and urine products are equally as effective as mineral fertilizer especially in sandy soil and that splitting the application is a useful strategy to manage urine and urine products for optimum dry matter production.
Ethylmethanesulfonate mutagenesis in selected Vernonia galamensis variety ethiopica lines.
(2012) Hadebe, Sandile Thamsanqa.; Odindo, Alfred Oduor.; Shimelis, Hussein Ali.
The overriding objective of this study was to induce genetic variation in Vernonia (Vernonia galamensis variety ethiopica) using ethylmethanesulfonate (EMS) and select mutants for subsequent selective breeding. Vernonia is an underutilised, potential novel oilseed crop with multiple applications in industry mostly due to the production of naturally epoxidised vernolic acid oil. Commercial cultivation of vernonia is significantly hampered by non-uniform seed maturity, tall plant height, seed shattering and lack of appropriate technologies for mechanical harvesting, seed threshing and cleaning. Mutations of a single or few genes possessing target traits are invaluable in crop improvement programs. Chemical mutagenesis using EMS is an important, affordable and effective method to induce random useful genetic mutations in crop plants. Ethylmethanesulfonate mutagenesis has previously been reported to affect various agronomic traits, induce a wide variety of phenotypic mutations and alter both seed oil content and fatty acid profile on several crops. The objectives of this study were: (i) to determine an optimum EMS treatment combination i.e. exposure duration, temperature and dose that would enable 50-60% germination at minimum days to emergence in selected V. galamensis var. ethiopica lines (Vge-1, Vge-4, Vge-7 and Vge-10), (ii) to induce genetic variation using predetermined optimal treatment conditions and select mutants in V. galamensis variety ethiopica lines (Vge-1 and Vge-4) and (iii) to evaluate oil content and fatty acid compositions among seeds of chloroplast mutants, EMS treated seeds and untreated controls of Vge-1 and Vge-4. Before any mutation is administered in plants, it is important that the optimal mutation dose is determined. The lethal dose 50 (LD50) was the standard used in this study to find optimal treatment conditions. Significant interactions (P<0.001) existed between EMS, line, time and temperature with respect to days to 50% emergence, germination percentage and seedling height. Optimal days to 50% emergence (10-12 days) and germination (50- 58%) was achieved for Vge-1, Vge-7 and Vge-10 when treated with 0.372% EMS at 350C for 1 hour treatment. The optimal treatment combination for Vge-4 was 0.372% EMS at 32.50C for 2hr. The treatment combinations that yielded optimum results in the tested lines were utilized to induce large scale mutations in V. galamensis to select target mutants in the field. Large scale mutation was conducted using the observed optimal treatment conditions. Ethylmethanesulfonate mutagenesis significantly delayed days to head formation, days to flowering and days to maturity on both lines. Delays in days to emergence were only significant in Vge-4. EMS treatment also significantly reduced germination percentage, number of seeds per head, number of fertile plants, plant height and plot yield for both Vge-1 and Vge-4. Thousand seed weight significantly increased in treated seeds of the two lines. Chlorophyll mutants were observed for tested lines associated with high count of sterility for both lines. Ethylmethanesulfonate successfully induced phenotypic mutation in selected vernonia lines, however at this stage the effect of mutation on vernonia seed oil content and fatty acid was unknown. Liquid gas chromatography method was employed for oil and fatty acids analysis. In Vge-1, significant differences were observed in composition of linoleic and oleic acid due to the mutagenesis. Significant increases in linoleic and oleic acid composition were found in chloroplast mutants due to EMS mutagenesis. No significant differences were detected in fatty acid compositions in Vge-4 after the EMS treatment. Differential responses were observed when lines were compared at various EMS mutation levels showing significant effect on vernolic, linoleic and oleic acids compositions. In both lines no differences were detected on seed oil content, palmitic acid, steraic acid and arachidic acid compositions after the treatment. Oil content significantly and positively correlated with vernolic acid for Vge-1 (P<0.001; r= 0.898) and Vge-4 (P<0.05; r= 0.65). Vernolic acid significantly and negatively correlated with other fatty acids. The study found that EMS mutagenesis significantly changed the oleic acid and linoleic acid compositions in vernonia. However, the oil content and vernolic acid composition were not significantly affected by EMS treatment. This study established that EMS was successful in inducing genetic variation (in agronomic traits, seed oil content and fatty acid composition) in the two tested lines of V. galamensis. Data from a single planting generation is insufficient to conclude fully on the effect of EMS on V. galamensis; therefore it is highly recommended that further multigenerational studies should be conducted with an increased number of testing lines from a wide range of environmental backgrounds.
Evaluating seed quality and performance of low and high phytic acid maize (Zea mays L.) under varying phosphorus rates and water regimes in dryland conditions.
Bakhite, Mohammed Abdalla Elgorashi.; Odindo, Alfred Oduor.; Magwaza, Lembe Samukelo.
Maize (Zea mays) being the staple crop for many communities in Sub-Saharan Africa and also used for animal feeding, a considerable effort has been made to improve quality and yield. In recent times plant breeders have focused on reducing phytic acid (PA) on maize seeds to improve grain nutritional quality. Although studies of low phytic acid genes have been reported in temperate maize, the current research was based on the tropical genetic background which was screened for low phytic acid. This is the first report for applied breeding of the trait in the tropical maize. Little is known on the agronomy and responses of tropical maize specifically to water stress and its response to phosphorus application. No studies provided on the seed quality performance and response of low phytic acid maize to water stress and phosphorus application. Reducing Phytic acid of tropical maize could have negative effects on seed quality and yield. The primary objective of this study was to compare the performance of low phytic acid (LPA) maize seeds of tropical origin with three other varieties i.e. high phytic acid (HPA) of tropical origin, SC701 and LS8520 based on seed quality and water stress. The study consisted of two maize synthetic populations differing in phytic acid (PA) content (from the African Center of Crop Improvement (ACCI)); namely, LPA and HPA synthetic populations. Both the LPA and HPA synthetic populations were derived from a tropical second generation (F2) population and were selected based on their phytic acid (PA) content. They were produced at the Ukulinga Research Farm, University of KwaZulu-Natal (29°40'05.7"S 30°24'20.9"E), in Pietermaritzburg, South Africa. These two maize synthetic populations were compared with two commercial maize varieties (from McDonald Seeds), white maize (SC701) and yellow maize LS 8520 R (484) which in this study was coded LS8520. All seeds used in this study were produced under identical production conditions and in the same growing season, thereby ensuring that the seeds were of the same physiological age. The first experiment investigated the characterisation of LPA maize varieties for seed germination and vigour. Seed quality was evaluated using the standard germination test and accelerate aging test together with electric conductivity test (EC). The second experiment was conducted as a pot trial to investigate the effect of exogenous phosphorus application on seed quality and yield of low phytic acid maize varieties. In third experiment, a field study over two seasons (2015/2016 and 2016/2017) was conducted at Ukulinga Research Farm in Pietermaritzburg, under dryland conditions. The objective of the experiment was to evaluate the newly produced ACCI’s two genetically synthetic maize populations of LPA and HPA under dryland field condition and compare them with the commercial white and yellow tropical maize varieties their germination, growth, yield and yield components. Lastly, an experiment under controlled conditions on photosynthetic efficiency and yield responses of LPA and HPA maize tropical lines to deficit irrigation. The study was carried out under controlled environment conditions. The objective was to evaluate the photosynthetic efficiency of low phytic acid (LPA) and high phytic acid (HPA) tropical maize varieties grown under water-stressed conditions. The results of the first experiment indicated that the performance of LPA varieties was comparable to those of commercially produced varieties. This study suggests that the combination of LPA lines of tropical origin used in this study was satisfactory to meet the minimum seed quality parameters particularly seed germination and vigour. The results for phosphorus application showed that the application of phosphorus improved the growth, flowering and yield of LPA and other varieties as well. The mean germination time (MGT), germination vigour index (GVI), electrical conductivity (EC) (μS g-1), root length, shoot length and the root-shoot ratio of the harvested seeds after phosphorus application were also improved. When the LPA and HPA tropical maize exposed to dryland environments the results revealed that the SC701 variety outperformed the other three varietiess in growth and yield. It was concluded that the LPA maize performed lower under field conditions. In the water stress trial, results showed that LPA maize varieties recorded higher values of stomatal conductance (gs) and transpiration rate (T) compared to HPA and SC701 for both normal and water stress conditions. HPA showed a significantly (P< 0.001) higher value of photosynthetic rate (A) than LPA and SC701 for all the water stress treatments. HPA and SC701 were comparable in most of chlorophyll fluorescence parameters. With regard to yield, HPA showed increased performance in terms of overall yield and seed weight, and this suggests that HPA varieties are less sensitive to water stress than LPA maize varieties. The results from this study have proven that LPA maize varieties are sensitive to limited conditions and further research under a wide range of environmental conditions is required. Overall, the results indicated that the seed germination of LPA was comparable to other varieties but the yield remains low. There is a need to conduct more experiments to demonstrate the performance of LPA under field conditions in response to phosphorus application and water stress. These differences between the traits could help breed programs. The selection for LPA and HPA tropical maize should be based on their physiological performance to be planted in temperate zones to grant higher yield performance.