Variation for temporary waterlogging response within the mini core pigeonpea germplasm

Pigeonpea is an important rainfed pulse crop grown in the rainy season that is subject to waterlogging. There are not many sources of waterlogging tolerance available; therefore the mini core pigeonpea germplasm (n = 146) were screened, along with a few genotypes already reported to exhibit tolerance. Five trials were conducted starting at 40 and 50 days after sowing (DAS) in 2008, and at 40, 62 and 76 DAS in 2009. The mortality rate in any trial depended on the vapour pressure deficits (VPD) that prevailed during waterlogging and the recovery periods. There were large and highly significant variations due to genotype and to genotype x trial interactions. The heritability of individual trials ranged from 0.27 to 0.75, while it was 0.40 when all the trials were considered together. The survival counts were grouped into representative groups using a hierarchical cluster analysis, which yielded five distinctive groups. The highly tolerant group, with above-average survival means in all five trials, comprised 24 accessions. None of the previously tested or control entries appeared in this group. The sensitive entries comprised 37 accessions including ICP 7035, ICP 8338 and ICP 13562, which were known to be sensitive from previous reports. The tolerant group comprised 39 accessions, moderately tolerant 42 and moderately sensitive 18. Survival during waterlogging and a rapid recovery are considered equally important for categorizing the genotypes and their further use.