Physiological Resilience of Bambara Groundnut (Vigna subterranea L. Verdc) Genotypes to Intermittent Periods of Drought Stress at Different Growth Stages

Different genotypes of Bambara groundnut (Vigna subterranea L. Verdc) grow well under conducive environmental conditions, provided that adequate soil moisture is available during vegetative and reproductive phases. However, drought stress is the major limiting factor to bambara production, which accounts for up to 40% of yield losses. This situation could worsen due to drastic and rapid changes in the global climate. Landraces grown by farmers are low-yielding. Understanding the physiological response of different genotypes to drought stress is key to achieving food security through crop improvement and diversification. This study focused on variations in the response of Bambara groundnut genotypes to intermittent drought stress during the crop’s critical growth (vegetative and reproductive) stages. The experiment was undertaken at CSIR-Crops Research Institute Screen-house. The treatments were used in a factorial experiment with three replications in a randomized complete block design. The Bambara genotypes showed considerable variability in tolerance to drought stress. Drought stress during vegetative and reproductive stages significantly reduced crop growth indices, the leaf relative water content, chlorophyll content and leaf area. Drought stress during vegetative and reproductive stages had a more severe impact on the seed yield of genotype Nav Red, reducing it by 69% and 13%, respectively. Farmers should pay more attention to adopting drought-tolerant and high-yielding varieties for improved Bambara groundnut productivity and livelihoods.

Enhancing the Productivity and Sustainability of Bambara Groundnut (Vigna subterranea (L.) Verdc.) Production Using Inorganic Phosphorus Fertilizer

Phosphorus (P) is a vital element required for nodulation, stomatal regulation and photosynthesis in legume crops. P-deficiency in tropical soils limits the growth and productivity of Bambara groundnuts. The current study focused on determining the potential suitability of underutilized crops for food security using phosphorus fertilizer as soil amendment practice. A field trial was carried out at the Council for Scientific and Industrial Research—Crops Research Institute (CSIR-CRI), over two growing seasons to determine the optimum P rate for Bambara production. This trial was laid out in a split plot in a randomized block design with three replications. Bambara genotypes represented the main plots while four P fertilizer rates (0, 30, 45 and 60 kg P2O5 ha-1) were the sub-plots. The appropriate application rate of 60 kg P2O5 ha-1 showed excellent performance based on growth and yield analysis, and the results indicate a positive significant interaction between landraces and phosphorus fertilizer rates. The biological suitability of 60 kg P2O5 ha-1 increased the number of nodules per plant for Tiga Necuru, Kenya Capstone and Nav Red by 42.8%, 51.3% and 42.1% respectively, over control plots. The same for pod yield is 12%, 28% and 52% significantly higher than when P was applied at 45, 30 and 0 kg P2O5 ha-1 respectively. The results further revealed that on days to flowering and maturity, the plant height, the number of branches and dry matter increased significantly at each level of P fertilizer rate applied. Bambara production at 0 kg P fertilizer rate might not be sufficient to enhance Bambara productivity significantly. The outcome of this study reveals the suitability of phosphorus fertilizer application in enhancing the sustainability of Bambara groundnut productivity and the potential of Bambara in diversifying crop production to ensure food security.