Effects of Different-growing-stage Shading on Rice Grain-filling and Yield

A split-plot design was used as the main plot treatment to study the effects of different-growing-stage shading(tillering stage,elongating-heading stage and filling stage) on rice grain-filling and yield,with 16 hybrid rice combinations as the subplot treatments.The results showed that the grain filling and yield were obviously affected by shading.During tillering stage,shading made the effective panicles reduce significantly,the filled grain degree and filled grain percentage decline by 3.00%,4.03% respectively,and the yield by 17.34%.During elongating stage,shading made the filled grain degree and filled grain percentage higher than those of the control by 3.84% and 9.94%,but the yield declined by 41.35%.During filling stage,shading affected pollination and grain growth seriously,and made filled grain degree and filled grain percentage decline by 7.41% and 16.64% respectively,while the yield declined by 53.93%.At last,the cluster analysis showed that hybrid rice combinations Yifeng-8 and Gangyou 906 had better tolerance of shading.