含籼率对连晚直播稻产量的影响

连作晚稻田中的秋籼，对连晚直播粳稻的产量影响很大。含籼1％减产2．5％，但未选显著标点；含籼5%减产17．0％；含籼10％减产22．1％；含籼超过15％减产32．6％以上，均达到极显著标点。所以，连晚直播稻的含籼率临界值为1％。减产的主要原因是有效穗和每穗实粒锐减。

Effect of Indica Rice Content on the Yield of Direct-Seeded Late Japanica Rice

Autumn indica rice greatly affected yields of directseeded late japonica rice. A 2. 5% yield loss was investigated in fields containing 1% indica rice and showed no difference at 5% significant level comparing with the yield in a field of no indica rice. However 1% level significant yield losses showed when indica rice content in direct seeded late rice fields reached at 5% and over.And the yield losses at different indica rice content were investigated as follows: 17% yield loss at 5% indica rice content; 22.1% yield loss at 10% indica rice content; More than 32. 6% yield losses at 15% indica rice content or over. Therefore,the critical value for indica rice content in direct seeded late rice fields is 1%. Main causes of yield loss are decreasing of effective panicles and number of filled grains per pnicle.