Genotypic selection approach made successful advancement in developing drought tolerance in perennial tree crop coconut

Abstract

Coconut (Cocos nucifera L.) is a major plantation crop in humid tropics that affects the socio-economic life of several developing countries. Being a rainfed crop, coconut is highly prone to drought and breeding for drought tolerance has become a high priority research. We have identified that selection within populations as the way forward to improve drought tolerance. The current study evaluates the comparative performance of Ambakelle special (AS), a progeny of a within population selection with unselected CRIC60 to identify stable higher yielding palms for future breeding programs. Six-year yield data (2014-2019) from 110 palms in each group were evaluated. Results revealed variety, year and interaction have significant impact on annual yield (P<0.05) however, variety x year showed a non-cross-over interaction. AS recorded significant higher mean annual yield (101 nuts/palm/year) compared to CRIC60 (90 nuts/palm/year). Due to low rainfall condition prevailed from July 2016; lower nut yields were recorded for both varieties in 2017 and 2018. However, AS maintained its superiority indicating a better adaptation than CRIC60 under low rainfall conditions. Regression coefficient (bi) and mean annual yield were used in stability analysis and selected 45 palms as stable and higher yielding genotypes. Out of these 45 palms, thirty-three palms (73.3%) were from AS progeny further indicating the adaptability of AS to varying environmental conditions. Twenty palms (16 AS and 4 CRIC60) were further selected using variance of deviations from the regression (S2di) and mean kernel weight to be used in the future breeding programs for drought tolerance in coconut.