Patterns of osmotic adjustment in pigeonpea-its importance as a mechanism of drought resistance.

摘要

Using two automated rain shelters, 26 extra short-duration pigeonpea (Cajanus cajan) genotypes were grown with irrigation throughout the growth period or with water stress from flowering until maturity. Mean leaf osmotic potential at full turgor (PSIs100) 60-92 days after sowing (DAS) under water stress correlated significantly with the mean osmotic adjustment (OA) 60-92 DAS and contributed 72% of the genotypic variation in OA. Significant genotypic variation was observed in the initiation, duration and degree of OA. Based on the measured OA at 72, 82 and 92 DAS, genotypes were grouped into 5 different clusters. Genotypic differences in total dry matter production under water stress were positively associated with OA at 72 DAS. There was a significant positive relationship between OA at 72 DAS and seed yield under water stress. However, OA towards the end of the pod filling phase, i.e. at 92 DAS, had a significant negative relationship with seed yield under water stress. Genotypic differences inseed yield under water stress were best explained using stepwise multiple regression to account for differences in OA at 72, 82 and 92 DAS. The degree of OA at 72 and 82 DAS contributed positively to the seed yield, whereas OA at 92 DAS contributed negatively to this relationship.