水稻纹枯病菌营养及寄主资源生态位

由于IPM概念的局限性，有害生物生态调控（EPM）理论和方法的提出发展了IPM，生态位原则是有害生物生态调控（EPM）的重要原则之一，生态位研究为EPM的具体实施提供了依据。应用可持续农业和EPM理论及生态位理论研究了水稻纹枯病的生态位，分析了水稻纹枯病菌氮肥营养生态位和寄主品种资源生态位，结果表明：以相对侵染效率作为指标，在水稻不同生育期，纹枯病的氮肥营养生态位宽度不同，其中以孕穗期的生态位宽度最小，为0.6979，拔节期、抽穗期、灌浆期和乳熟期的生态位宽度分别是0.9741，0.8884，0.7974和0.9815，表明水稻纹枯病在水稻不同生育阶段利用氮肥的效能不同。寄主品种资源生态位宽度在拔节期、孕穗期、抽穗期、乳熟期分别为0.9348，0.7677，0.8875和0.9962。以病情指数为指标，氮肥营养生态位宽度在拔节期、孕穗期、抽穗期、灌浆期和乳熟期分别为0.9379，0.9696，0.6775，0.6729和0.7691。其氮肥营养生态位宽度在拔节期与孕穗期最大，生态位宽度指数接近于1。寄主品种资源生态位宽度在各生育期均接近1，表明寄主品种资源生态位宽度在各生育期是相似的，即说明水长期稻纹枯病菌利用品种资源各状态的选择和利用效能是相似的。

Vertical distribution of algae in semi-desert soil of Shapotou area,Ningxia Hui Autonomous Region

Because of limitation of the Integrated Pest Mangagement(IPM) concept and social,economical, technical and organizational obstacles,the adoptive rate of IPM by farmers has been very low.The principles and methods of Ecological Pest Management(EPM) are proposed for development of IPM.In the paper,theory of sustainable agriculture,theory of EPM and niche theory were used to study the niche of rice sheath blight fungus.Principle of niche is one of important principles about EPM.Study on niche could provide applicable basis for EPM. The trophic of nitrogen fertilizer and host niches were analyzed. The results show that according to relative efficiency of infection, the niche breadths of trophicity of nitrogen fertilizer was the minimum at booting stage,that was 0.6979,and the niche breadths of trophicity of nitrogen fertilizer were 0.9741,0.8884,0.7974 and 0.9815 at jointing stage,heading stage,filling stage and milking stage,respectively.The utilization ratios of nitrogen fertilizer for rice sheath blight fungus were different at different growth stages of rice.At jointing stage,booting stage,heading stage,and milking stage, the host niche breadths of rice sheath blight fungus were 0.9348,0.7677,0.8875 and 0.9962,respectively. According to disease index , at jointing stage, booting stage,heading stage,and milking stage, the niche breadths of trophicity of nitrogen fertilizer of rice sheath blight fungus were 0.9379,0.9696,0.6775,0.6729 and 0.7691,respectively.rice sheath blight had bigger niche breadths at jointing and booting stage as compared with those of other growth stages, and the indexes of niche breadths approached 1 at jointing and booting stages. At jointing stage,heading stage,filling stage and milking stage, the host niche breadths of rice sheath blight fungus were 0.9464,0.9188,0.9262 and 0.9595,respectively.They were similar, all approached 1.So,the selection property of fungus for cultivars was similar.