STUDIES ON THE HETEROSIS OF INTERSUBSPECIES IN RICE

In the experiment,several photoperiod-temperature sensitive genie male sterile lines and some indica,japonica or javanica varieties (including wide compatibility varieties) were crossed to obtain 25 intersubspecificF1 hybrids(17 indica-japonica and 8 indica-javanica hybrids),15 intervarietal F1 hybrids.The feature andproblem in use of intersubspecies heterosis in south China region of two season rice were pointed out.The results indicated,Principal problem of intersubspecif ic F1 hybrid of two lines was lower setting percentage and grain-straw ratio.Indica-japonica hybrid was susceptible to environment condition.Filled graings per panicle and panicles per plant were the important factors determining grain yield per plant.Setting percentage was the key character affecting filled grains per panicle.The suggestions for increasing setting percentage and grain-straw ratio had been proposed.