Effects of yield components and panicle traits on sink potential in conventional indica rice.

Eighty-eight and 122 conventional indica rice varieties were solution-cultured in 2001 and 2002,respectively,and tiller number dynamics,yield and its components,and panicle traits of these varieties were investigated.The tested rice varieties were classified into 6 types(i.e.A,B,C,D,E and F,A was the lowest,and F was the highest) based on their sink potential levels by the MinSSw method.Significant difference in sink potential(SP) among the varieties was found,the ratio of the maximal SP to the minimum in 2001 and 2002 were 426% and 817%,respectively.The average SP of the F-type varieties were 184.71%,88.93%,57.45%,34.32% and 14.05% higher in 2001,and 305.05%,153.54%,90.28%,51.24% and 21.29% higher in 2002,respectively than those of A-,B-,C-,D-,E-type varieties.With the enlarging SP,the grain yield increased significantly.Varieties belonging to large SP type had superiority in the number of panicles per unit area,number of spikelets per panicle and 1000-grain weight.Varieties with larger SP showed longer panicle,higher spikelet density and higher number of primary and secondary rachis branches on panicles.The contributions of the number of spikelets and number of panicles per unit area to SP were similar,which was significantly greater than that of 1000-grain-weight to SP.The number of spikelets per panicle was more affected by spikelet density and panicle length than by number of secondary rachis branches per panicle and the ratio of primary rachis branch number per panicle to secondary rachis branch number per panicle.