Effects of shading during late growth stage on different rice types

To study the effects of shading on different rice types, 13 medium indica maintainer lines, 4 conventional medium indica and 3 japonica varieties were used in this experiment. The effects of shading on various rice types＇ SPAD, per plant of effective panicles, 1000-grain weight, filled grains and economic yield at late growth stage were studied with artificial shading. The shading rate was about 45%. Results showed that the shading treatment significantly affected the maintainer lines＇ duration from seeding to heading, 1000-grain weight, SPAD of 5 d, per plant of effective panicles, filled grains and economic yield. Both of the two types of conventional varieties, only the effective panicles per plant of conventional indica varieties was significantly affected by shading, other effects were not significant. This indicated that the medium indica maintainer lines have poorer shading tolerance compared with conventional medium indica and japonica varieties. But the mechanism needs further study.