Evaluation of water-deficit stress tolerance in Bambara groundnut landraces for cultivation in sub-tropical environments in India

Abstract

In the perspective of climate change scenario, resilient crops are essential for future cultivation. Bambara groundnut (Vigna subterranea L. Verdc.) is legume and well known for its drought tolerance, mainly cultivated in Africa. This study was under taken to evaluate Bambara groundnut landraces for pod and biomass yields. Promising landraces were analysed for drought tolerance under fully irrigated (IR100), 50% water cut (IR50) and progressive water-deficit stress for 6 days (IR0) in pot culture experiment. Wide variations were recorded in leaf chlorophyll and carotenoid, chlorophyll a fluorescence, relative water content, water potential, proline, epicuticular wax load, vegetative growth and pod yields, under different soil moisture regimes. Drought tolerant landraces were able to maintain leaf-water-relation traits and photosynthetic efficiency under both IR50 and IR0. Such as, slopes between relative water content and depleting soil moisture in IR0 were higher in SB 4-2 (3.5) and Uniswa Red (2.6) and, lower in DodR Tz (2.0) and S 19-3 (1.9). Also, leaf epicuticular wax load showed different patterns both in its inherent and acquired potential, for example, inherent potential was lower and acquired higher in SB 4-2, while inherent potential was higher and acquired lower in S 19-3. Under normal irrigation, pod and biomass yields were higher in DodR Tz and SB 4-2 whereas reduction in pod and biomass yields were lower in S 19-3 and DodR Tz, under water-deficit. Variations in all characters studied were significantly (P < 0.01) influenced by landrace, suggesting a strong genetic basis for the phenotypic differences amongst landraces. Thus, characteristics of S 19-3 in drought tolerance and SB 4-2 in higher biomass in IR100 could be used for improving drought tolerance for different water scarcity environments, world-wide.