硅对叶螨危害后棉花防御酶活性的调控作用及其与抗虫性的关系

以棉花品种新陆早33号感染土耳其斯坦叶螨（Tetranychus turkestani（Ugarov ＆ Nikolski））作个案研究，阐明硅提高棉花抗螨性的生理机理。网室条件下采用微区试验设计，硅肥采用喷施和基施处理，研究不同时间棉花的虫害指数、干物质积累量和硅含量，以及与植物抗性密切相关的过氧化物酶（POD）、多酚氧化酶（PP0）和苯丙氨酸解氨酶（PAL）活性变化。结果显示：不同施硅处理缓解了棉花叶片受叶螨危害的症状，在接种叶螨第6天硅处理降低了叶片受害指数；施硅处理提高了PPO和PAL的活性，而降低了参与清除植物体内活性氧功能的POD活性。硅能够调控棉花与抗虫有关的酚类物质代谢过程，参与植物防卫反应而增强棉花对土耳其斯坦叶螨的抗性。

Silicon-Mediated Defense Enzyme Activities in Cotton Attacked by Tetranychus turkestani and Its Insect Resistance

Cotton （Gossypiurn herbaceum cv. Xinluzao33） inoculated with T. turkestani was used as a case study to elucidate the physiological roles of silicon in improving pest resistance. A field experiment was designed consisting of 6 silicon treatments with or without pest inoculation..i.e, no Si added, foliar application of Si at 1.7 mmol Si · L^-1, and basal application of Si at a rate of 0. 725g · m^-2 as Na2 SiO3. The experiment was performed to investigate the effects of silicon application on the damage index, growth parameter, silicon content and peroxidase （POD）, polyphenoloxidase （PPO） and phenylalanine ammonia-tyase （PAL） activities. Silicon treatment significantly alleviated the damage symptoms of cotton leaves and decreased leaf damage in- dex on the 6th day after infestation. Silicon enhanced the PPO and PAL activities but reduced the POD activity which is involved in scavenging reactive oxygen species. Silicon is involved in the plant defense response, and can regulate phenols metabolic processes associated with insect resistance,and consequently enhance the resistance of cotton to the attack by T. turkestanii .