Effect of two different water regimes on growth and yield of different groundnut (Arachis hypogaea L.) genotypes in Sri Lanka

Abstract

Drought resistance is an important character for increasing groundnut (Arachis hypogaea L.) yields in the sub-humid, dry zone of Sri Lanka. Therefore, the objective of this study was to determine the effect of soil water deficit on vegetative growth and seed yield, and to determine the physiological basis of yield of groundnut under water stress. Seven genotypes of groundnut (Tissa, ANKG-2, Red Spanish, M-45, ICGV86015, ICGV86I43 and ICGV86149) were grown under well-watered (90% available water) and water-stressed (30% available water) conditions in pots (12 kg) in a glasshouse at Maha IlluppaSlama, Sri Lanka. In all genotypes, water stress significantly reduced leaf area, final total dry weight and seed yield. Final total dry weight and yield showed significant genotypic variation under both water regimes but did not show significant genotype x water regime interaction. Under water-stressed conditions, the highest seed yield was produced by ICGV86015 whereas ICGV86149 had the highest yield under well-watered conditions. A greater partitioning of dry matter to seeds (i.e. greater harvest index) was required to achieve high groundnut yields under water stress. On the other hand, dry matter partitioning was not a yielddetermining parameter under well-watered conditions where a greater capacity for total biomass production was required to achieve high yields. Under water-stressed conditions, groundnut yields were positively correlated with pod number per plant, seed weight and the number of primary roots per plant.