STUDIES ON VARIETAL DIFFERENCES IN COMPONENTS OF PANICLE WEIGHT IN RICE

The differences in panicle weight components, including number of spikelets, seed setting percentage and 1000-grain weight at different part along the panicle, among rice varieties with different ear-type and root traits were studied in pot experiment. The factors influencing panicle weight were analysed. Results were as follows: ①The ratios of primary spikelets to spikelets of whole panicle (Rp) in three locations along the panicle (i.e. upper, middle, lower) in large-ear type variety were lower than those in small-ear type variety, especially in the middle part, while the ratios of the secondary spikelets to whole panicle spikelets (Rs) at middle and lower parts in large-ear type variety were higher than those in small-ear type variety. ②The Rp was lower and Rs was higher in Indica rice, but the reverse trend appeared in Japonica rice. ③The differences of grain setting percentage and 1000-grain weight in primary and secondary spikelets were larger in Japonica varieties than those in Indica varieties.④Panicle weight could be enhanced by increasing the number of spikelets per panicle, seed setting rate and 1000-grain weight, among which the number of spikelets per panicle, especially in the secondary branches, was more effective.⑤Developed root traits were the important characteristics in weight-ear type rice varieties.