弱光胁迫对超级杂交稻适应性的影响

Super hybrid rice apparently showed the high yield potential under ecological conditions of the mountainous areas. However, the yield decreased dramatically because of insufficient sunshine during the grain filling stage in plain area. This experiment was conducted with super hybrid rice and ordinary hybrid rice to discuss effects of shading treatment on the grain yield and photosynthesis characteristics of rice. The sun shading nets have been used to filter light intensity about 60% since the full heading stage. The results showed that super hybrid rice was sensitive to low light and the interaction between varieties and treatment was also significant. In addition, the yield of super hybrid rice decreased by 41.8% to 46.8% under the shading stress. Grain filling, spikelet number and 1000-grain weight were all significantly influenced by shading treatment except panicle number. The percentage of dry matter transferring to grains in super hybrid rice was much lower at 40.2% compared to the one of ordinary hybrid rice, at 44.2%. The SPAD value of the super hybrid rice increased, but the net photosynthetic rate of the flag leaf and dry matter accumulation and distribution decreased. The root cause of yield reduction in super hybrid rice cultivars is that sink and source of super hybrid rice was limited more heavily than that of ordinary hybrid by shading stress. Since shading has effect on rice during grain filling stage it is necessary to consider the local climates when promoting super hybrid rice varieties in different regions to benefit the full use of its high yield advantages.