Constitutive traits and selective indices of Bambara groundnut ( Vigna subterranea (L) Verdc) landraces for drought tolerance under Botswana conditions

Constitutive traits of 12 landraces of Bamabra groundnut ( Vigna subterranea (L) Verdc) were studied during the 1999/2000 and 2000/2001 at the Botswana College of Agriculture, for traits which relate to the crop’s adaptation to drought. The objective was to estimate the degree of phenotypic and genotypic variation of traits whose selection would lead to earliness in maturity and drought tolerance through drought escape. The landraces showed significant diversity. Low environmental variability was recorded for days to maturity, root:shoot ratio, canopy spread, number of seeds per pod, 100-seed weight and shelling percentage. Genotypic correlation coefficients and path coefficient of number of pods per plant and seed size on yield were significantly high. The results of this experiment indicate that, canopy spread, root:shoot ratio, 100-seed weight and number of seeds per pod are among parameters that could be used for indirect selection for drought tolerance in Bambara groundnut in Botswana and other areas where drought is a common occurrence.