棉花耐害补偿临界指标及其应用的探讨

棉花耐害补偿反应可归纳为三种动态类型：1)不足补偿动态反应型；2)完全——不足补偿动态反应型；3)超越——完全——不足补偿动态反应型。其临界指标的建立及其应用可优化棉花病虫害综防决策．以研究害虫防治决策为例，剖析了利用害虫自然种群，人为改变害虫自然种群、人为地接放一定虫量与人工损害模拟等不同测定棉花耐害补偿能力方法的利弊。并探讨改进措施．分析论述了不同量化棉花耐害补偿能力的方法，并就棉花耐害补偿临界指标的建立及其意义作了探讨．棉花耐害补偿临界描标在棉田生态系统有害生物综合治理中可用于指导防治决策或直接用于防治决策，有着十分广阔的应用前景．最后就棉花耐害补偿临界指标及其应用的研究方向及有关问题作了讨论。

APPROACHES FOR ESTABLISHING THE COMPENSATION THRESHOLD OF COTTON PLANT TO THE INJURY OF INSECT PESTS

the dynamic model of pest injury to the final yield of cotton can be summarized into three types:(1)un-compensable type,the yield of cotton will decrease as the injury level of pests increases;(2) compensable type,the cotton plant is tolerable to certain level of injury with no loss of yield and the yield of cotton will decrease only when the injury is over the point of limited tolerence;(3)over compensable type,the yield of cotton may increase when a certain level of injury exists and decreasing of yield occurs when the inju- ry level is over the point of tolerence.So establishing the point of tolerence or the compensation threshold of cotton plant to various pest injury is important for optimizing the decision of control.The approaches for es- tablishing the compensation threshold of cotton plant to various pests can be accomplished by estimating the injury caused by natural population of pests under the field condition;or estimating the injury level caused by various level of pest population through the pesticide control or natural enemies;or by inoculating various number of pests in different plots to cause different level of injuries;or by simulating injuries by manual labor.Those approaches were reviewed and evaluated,and the compensation thresholds of various pests were illustrated in the paper.By using the compensation threshold it may improve the decision of control in the IPM system of cotton pest control.