Genetic studies on leaf rolling and some root traits under drought conditions in rice (Oryza sativa L.)

Crossing was made between three resistant and two susceptible parents to determine the genetic characteristics under drought conditions during 2002 and 2003 rice growing seasons. The resistant varieties were IET 1444, Moroberekan and Gaori, while the susceptible varieties were Sakha 101 and Sakha 102. Measurements on genetic variability, inbreeding depression, heritabillity, potence ratio, heterosis and genetic advance, were calculated for parents, F1 and F2 populations from the three studied crosses. The F2 and F3 lines derived from six crosses were grown in a RCBD experiment in three replications to study the genetic of leaf rolling. The total number of lines in F2 segregated 3:1 (rolled : unrolled) and F3 lines segregated in 1:2:1 (rolled : segregating : unrolled). The results showed that plants which showed more leaf rolling appeared to be less drought resistance. It was also found that the recovery ability was associated with drought resistance and leaf unrolling character. Measurements on genetic variability, heterosis, inbreeding depression, potence ratio, heritabillity and genetic advance under selection were calculated. Desirable significant heterosis was found for grain yield/plant, root length, root thickness and root:shoot ratio for all the studied crosses. Potence ratio indicated over dominance for all studied characters in the three crosses except for root thickness and root : shoot ratio in the cross II (IET1444 x Sakha 102), for grain yield/plant and root length in the cross III (Moroberekarn x Sakha 101). High heritabillity values were associated with high genetic advance for days to heading and plant height in all studied crosses, while there were no associations with high genetic advance in the other characters.