Genetics of drought tolerance in rice

Abstract

newline The present investigation was carried out at Instructional-Cum-Research Farm of Assam newlineAgricultural University, Jorhat with the objectives - (i) To assess genetic diversity for drought newlinetolerance in rice and (ii) To study the combining ability and gene action. We evaluated 46 rice newlinegenotypes in water sufficient non-stress and water-deficit stress conditions during Ahu season of newline2018 in PVC pipes. Evaluation of the 6-parent diallel crosses was carried out during Ahu 2019 in newlineplastic tubs. The phenotypic evaluation revealed significant variation for all the characters. Leaf newlinerolling (LR) and drought recovery (DR) had a significant correlation with root traits only, newlinepositive with root length and negative with root dry matter and root-shoot ratio. Based on the newlinelowest average LR plus DR score of unity, Basantabahar, Haru Bengunigootia, Lewly, Basmoti newlineRed, Banglami, Ikhojoi, Dimrou, Lachit, Disang and Inglongkiri possessed tolerance to drought newlinestress (7-8% soil moisture content) both at vegetative stage up to 3 weeks and reproductive stage newlineup to 1 week. Root-shoot ratio, root dry weight, proline content, root length, productive tillers, newlinegrain yield, grains per panicle and biomass yield registered a high magnitude of PCV and GCV newlineestimates. High heritability coupled with high genetic advance for 1000-grain weights, proline newlinecontent, grains per panicle, root dry weight, days to first panicle emergence, days to 50% newlineflowering, root-shoot ratio, biomass yield per plant, root length, grain yield per plant, productive newlinetillers per plant, harvest index and shoot length implicating the role of additive gene action and newlinescope of simple selection for these traits. D2 statistics grouped the genotypes into 14 clusters with newlinethe highest inter-cluster distance between cluster V-XIII and V-XII. Thousand-grain weights newlinecontributed the maximum (74.69%) to the genetic divergence among the genotypes followed by newlinegrains per panicle (9.76), proline content (3.29%), root dry weight (3.09%) and grain yield per newlineplant (2.71%)...