间套种绿肥防控柑橘半穿刺线虫的机制研究

The citrus nematode, Tylenchulus semipenetrans, widely distributes in China, causes significant economic losses in all citrus-growing regions of China. Current the citrus nematode management relies heavily on the nematicide. This chemicalbased management is of high risk for the environment. When Citrus is grown in the hills, it is difficult to water, fertilize, and more difficult to controlling nematode in Guangxi , intercropping green manure crop with citrus not only offers one such alternative for nematode management, but could enhance soil fertility and soil structure, reduce soil erosion. In this study, the suppressive Effect of green manure crop intercropped with citrus on Tylenchulus semipenetrans population densities were evaluated, and the subsequent residual effects of the plant residue on population changes of Tylenchulus semipenetrans were evaluated too, meanwhile the microorganisms present in the Green Manure Crop rhizosphere were identified and their population changes in response to cover crop treatments were analyzed, we hold these would clarify the Mechanism of interplanting green manure crop for the control of citrus parasitic nematode Tylenchulus semipenetrans, and provide some theoretical basis for the ecological managements of citrus parasitic nematode

柑橘半穿刺线虫在柑橘产区广泛分布，引起严重的经济损失，目前主要以化学防治为主，化学杀线剂易造成柑橘品质下降、环境污染、土壤生物区系破坏、线虫产生抗药性等弊端，且广西大部分柑橘园为丘陵山地种植，施肥灌溉及施药工作实施难度大，选择具有趋避、毒杀线虫的绿肥进行合理间套种，不但可以从生态角度来解决柑橘半穿刺线虫防治难的问题，还可以保水保肥改善土壤微生态，促进柑橘健康成长。项目以柑橘半穿刺线虫为研究对象，筛选具有抑制或毒杀柑橘半穿刺线虫的绿肥，评价不同绿肥间套种对柑橘半穿刺线虫的防控效果，开展绿肥残体及处理方法对柑橘线虫病的防控效果的影响，研究绿肥间套种及绿肥残体对根际微生态和土壤肥力变化的影响，通过探讨分析防控效果与根际微生态等之间的关系，以期能够阐明间套种绿肥防控柑橘半穿刺线虫的作用机制，为柑橘半穿刺线虫的生态防治提供理论依据。项目的研究对于柑橘生产上化肥农药减施增效具有重要的意义。

项目开展了绿肥对柑橘园半穿刺线虫的的防控实验，结果显示间套种绿肥对半穿刺线虫的防控效果在0-62.44%，其中间套种万寿菊套种对半穿刺线虫的防控效果最好，防效为62.44%；其次为间套作黑麦草、苕子、苜蓿，防效分别为：55.75%、52.63%和44.91%。通过比较具有杀线虫功效的植物残体收获后处理措施析比较，发现对柑橘半穿刺线虫防控效果最优的处理技术为收获后直接翻埋进入土壤，防效达84.49%。利用高通量测序技术分析间套种黑麦草、苕子、苜蓿和万寿菊后柑橘根际土壤线虫的群落结构特征及群落多样性，结果显示间套种绿肥的柑橘根际土壤线虫的群落丰富度和多样性均比未间套种的高，其中万寿菊处理的丰富度最高，其Ace指数和Chao指数分别为47.50和24.50，Shannon指数为2.04，说明不同间套种绿肥种类对土壤线虫种群及微生物群落结构有明显的影响，间套种绿肥后土壤线虫多样性和丰富度高于未间套种处理，从而降低寄生性线虫的占比。线虫群落变化最明显的是柑橘半穿刺线虫，其比例明显降低，未间套种绿肥的柑橘根际土壤半穿刺线虫丰度为92.75%，而间套种万寿菊的柑橘根际土壤丰度降低到39.25%，随着改变的是其他属线虫丰度的提高。这对应于提高柑橘土壤线虫结构多样性和丰富度，从而从而提升柑橘园土壤的健康程度具有重要意义。