Comparison of Growth and Developmental Process and Yield Characteristics of Early Hybrid Rice Combinations with Different Maturity

Six early hybrid rice combinations were divided into two maturing groups: early group and late group,and a comparison was conducted on the growth and developmental process and yield characteristics between these two groups.The results showed that there was not a significant difference between early maturing hybrids and late maturing ones in leafing rate,young panicle differentiation duration(from young panicle initiation to heading) and young panicle differentiating rate,and grain filling duration(from heading to ripening).The significant difference in whole growth duration between them resulted primarily from their difference in vegetative growth stage.The earlygroup hybrids had a shorter vegetative growth duration and started young panicle initiation earlier so that they could get matured earlier than the late-group hybrids.In addition,there was not much difference between the early and late groups in such yield characteristics as effective panicles,spikelets per panicle,filled grains per panicle and seed setting rate.However,the economic yield and biomass of the early hybrids were very significantly lower than those of the late hybrids,resulting mainly from a lower 1000-grain weight and a shorter plant height for the early hybrids.It is indicated that enhancing leafing rate in vegetative growth period could be the key to coordinate early maturity and high yield for early hybrid rice,and it would be possible to achieve a breakthrough in breeding of early hybrid rice with both early maturity and high yield by selecting such cultivars with the characteristics of shorter vegetative growth duration,higher leafing rate,more main stem leaves,higher 1 000-grain weight and properly higher plant height as parents to make hybrids.