Effects of early growth stage shading on rice flag leaf physiological characters and grain growth at grain-filling stage
生育前期遮光对水稻灌浆期剑叶生理特性及籽粒生长的影响

In a pot experiment, rice plants were shaded during the period from transplanting to booting, aimed to study the effects of early growth stage shading on the rice growth at grain-filing stage.Comparing with the control, early growth stage shading decreased the tiller numbe by 26.72%.but increased the flag leaf area and soluble sugar content by 33.86% and 30.23%,respectively.The filled-grain number per panicle,1000-grain mass, ultimate brown rice mass, and maximum and average grain-filling rates decreased by 8.65%,4.81%,9.74%,20.22%,and 19.13%,and the effective panicle number and grain yield declined by 25.26%and 39.56%,respectively.The peak time of grain-filling rate (T_m) advanced 1.66 days, while the grain-filling time (T_(99))prolonged 6.80 days. For shading-tolerance variety, its flag leaf Chla, Chlb,and Chl(a+b)contents at early and mid grain-filling stages,and the protein N and soluble sugar contents and Chl a/b in its flag leaves at grain-filling stage all increased under early growth stage shading,and the ultimate brown rice mass and 1000-grain mass maintained at the similar levels as the control. Consequently.its grain yield reduction rate was lower than that of shading-sensitive variety.