Traits that confer post-flowering drought tolerance in short duration pigeonpea

Pigeonpea (Cajanus cajan) is one of the most important legume crop, ranking fifth in importance among edible legumes globally. It is adversely affected by intermittent and terminal droughts. As grain yield under drought is heavily influenced by genotype × environment interactions, a trait-based selection had been considered more beneficial in drought tolerance breeding. The objective of this study is to identify putative traits that confer yield advantages under post-flowering drought stress. Fifteen super early and early genotypes including breeding and germplasm lines, as a subset of greater number of test genotypes were field evaluated for pre and post-harvest physiological and agronomical traits. Significant variation was observed, among the genotypes, for the traits normalized difference vegetation index (NDVI) and SPAD chlorophyll meter reading, measured at different days after sowing at the reproductive phase, shoot biomass productivity, and yield components. Genotype × drought treatment interactions were found to be meager, especially in super early lines. Grain yield under drought was closely associated with NDVI measured at podfilling stage (r=0.86***), shoot biomass at maturity, harvest index (HI) and yield components. Though the genotypic variation in SPAD chlorophyll reading was large, its correlation with grain yield under drought was not significant. NDVI, a high throughput measure, was found to be significantly correlated with the other putative traits such as shoot biomass (r=0.91***), HI, pod number m-2 and seed number m-2 and therefore, can be used as a proxy in identifying better drought tolerant lines in crop improvement for early and super early pigeonpea