Genetic analysis for yield and drought tolerance traits in rice (Oryza sativa L.)

The experimental material consisted of six generations (P1, P2, F1, F2, BC1 and BC2), which resulted from two crosses, viz. ADT 45 × IR 64 Drt and MDU 6 × IR 64 Drt of rice using three parents. The experiment was carried out in a randomized block design with two replications to study the generation mean analysis. Correlation and path analysis were carried out using F2 generation. Thirteen traits, viz. days to 50 % flowering, plant height, number of productive tillers/plant, panicle length, number of filled grains / panicle, hundred grain weight, single plant yield, root length, root volume, root thickness, dry root weight, dry shoot weight and root/shoot ratio were studied for above analysis. In generation mean analysis, existence of dominance gene action along with one or more interaction effects, viz. additive x additive (i), additive x dominance (j) and dominance x dominance was observed for all the traits except grain yield and dry root weight which registered both additive and dominance gene action and epistatic components. Correlation analysis showed positive and significant association of grain yield with most of the yield and drought tolerant traits viz. productive tillers per plant, panicle length, filled grains per panicle, 100 grain weight, dry root weight, root length, root volume, root thickness and root/shoot ratio. Path analysis showed that many root characters viz. root thickness, root length, root volume and dry root weight exhibited positive direct effect on grain yield indicating their greater influence on yield under drought stress conditions. Number of filled grains also recorded positive direct effect on grain yield.