水稻纹枯病时空生态位施药干扰研究

以施药作为干扰因子,研究干扰条件下水稻纹枯病菌的时间和空间生态位变化.结果表明,各施药处理与对照纹枯病菌的空间生态位存在差异,其中孕穗期施药+齐穗期施药和孕穗期施药+灌浆期施药两处理的空间生态位宽度指数分别为0.520、0.572,与对照的空间生态位宽度指数0.8563相差最大;分蘖盛期一次施药处理的空间生态位宽度指数为0.8577,与对照相差最小.各施药处理和对照的时间生态位宽度无显著差异,表明施药对纹枯病菌的时间生态位宽度影响不大.空间生态位宽度指数、病叶(鞘)率、病情指数及防治效果等计测结果表明,两次施药对病害的控制好于一次施药,其中两次施药中以孕穗期施药+齐穗期施药和孕穗期施药+灌浆期施药对病害的控制作用最强.施药不但压缩了水稻纹枯病菌的空间生态位宽度,限制了其在产量形成较为重要的上部叶位的扩张,而且压缩了水稻纹枯病菌的时间生态位宽度,限制了其在水稻产量形成时期的扩张.但施药只改变了病菌生态位的分布,调整压缩了水稻产量形成期的病害生态位,病菌生态位势的总和不变.

Effects of fungicide on temporal and spatial niches of Rhizoctonia solani

This paper studied the variation of the temporal and spatial niches of rice sheath blight-causing Rhizoctonia solani under spraying fungicide. The results showed that between fungicide treatments and control, the spatial niche breadth of Rhizoctonia solani was different, while its temporal niche breadth was similar. The spatial niche breadth of Rhizoctonia solani was 0. 5240 when spraying fungicide at booting and full heading stages, 0. 5742 at booting and milkfilling stages, and 0. 8577 at tillering stage, while the control was 0. 8563. Spraying fungicide had little effect on temporal niche breath. The spatial niche breath, percentage of diseased leaves and sheathes, index of disease, and control effect all suggested that spraying fungicide two times in rice growth period was better than spraying it one time. Spraying fungicide at booting and full heading stages and at booting stage and milkfilling stages had the best effects. Fungicide could not only narrow the spatial niche breadth, limit the spread of Rhizoctonia solani on top leaves which were important for the yield, but also narrow the temporal niche breadth, limit the spread of Rhizoctonia solani during the yield formation period of rice. But, spraying fungicide only changed the distribution of the fungus niches and narrowed the niches during rice yield formation period, with no changes in the whole niches of Rhizoctonia solani.