Improving phosphorus uptake by cassava (Manihot esculanata Crantz) using Arbuscular Mycorrhizal Fungi (AMF)

Abstract

Phosphorus uptake cassava (Manihot esculanta Crantz) were tested using on thirty-six plants per plot under dryland conditions at four different sites selected Bioresource group 1 (BRG 1) of northern KwaZulu-Natal of South Africa, which is described as Moist, Coastal Forest, Thorn and Palm veld, exhibiting sub-tropical characteristics. Soils in this region are very low in Phosphorus (P) due to high fixation by iron and aluminium oxides. With its high root yields coupled with efficient nutrients miner, cassava removes large quantities of N, P, K and Mg. With the ever-increasing prices of P fertilizer, which impact on the socio-economic livelihood of smallscale farmers, there is the need to look into improving the P uptake by the crop by alternative means apart from using mineral fertilizers. The objective of this study was to investigate the use of Arbuscular Mycorrhizal Fungi (AMF) to improve P uptake by cassava in agricultural soils. Laboratory studies were conducted at Soil Fertility and Analytical Services in Cedara (Pietermaritzburg). A Latin Square design (LSD) was used. Four treatments used were Untreated (Control), P-fertilizer, AMF, and P + AMF. Correlation and path-coefficient (probabilities) were computed. The P + AMF were significantly (p<0.05) taller than those in P-fertilizer treatment plots but were significantly (p<0.05) similar to those in Control and AMF-treated plots. Percent leaf P was statistically similar at the four sites with grand mean of 0.4%. Adding AMF and P+AMF to the soil substantially increased leaf P concentration to 0.5%. Tubers collected from P+AMF-treated plots were significantly (p<0.05) the longest, while those from Control plots were the shortest. P, and AMF-treated plots increased tuber length relative to the Control. All soil treatments significantly (p<0.05) increased tuber yields over the Control-treatment plots. However, AMF and P+AMF treated plots were significantly higher than P and control plots. This study suggests that using AMF or P+AMF can improve cassava yield as compared P alone or control – untreated cassava plants. Cassava producers in northern KwaZulu- Natal should consider using AMF or P+AMF to optimize tuber yield. A further study into the economic implications of the use of AMF is recommended.