根系分泌物的化感作用与荞麦连作障碍的关系研究

Domestic and international researches showed that allelochemicals of roots are closely related with continuously-cultivating disturbance for crops, of which buckwheat show a more obvious disturbance than others. However, there are still no many researches about it. Therefore, choosing eight buckwheat varieties with different sensitivity to continuous cultivation as experimental materials, this project works on: (1) Separating and identifying the roots' secretion of different buckwheat varieties, and then identifying the materials causing allelochemicals which can do harm to continuous cultivation of buckwheat through the study on their physiological, biological and chemical index, DNA cross-linking, the content and proportion of endogenesis hormone, and their sensitive index of allelopathy. (2) Making clear the damaging mechanism brought by roots' allelochemicals to continuously-cultivated Buckwheat by means of studying the physical and chemical characteristics of root range soil, available nutrient, the quantities of microbe in the soil, the activities of protective enzyme, different expressions for protein, and the content and proportion change of the endogenous hormone, etc. (3) relieving buckwheat's continuously-cultivating disturbance in the way of controlling its density, fertilizer, water, and chemicals, reducing the concentration of allelopathy materials, and increasing buckwheat's ability of anti-allelopathy to self-poisoning substances in roots. These studies are valuable in clarifying the damaging mechanism for buckwheat's continuous cultivation and providing methods for decreasing buckwheat's continuously-cultivating disturbances.

国内外研究表明根系化感物质与作物连作障碍有密切关系。荞麦的连作障碍比其他主要作物更加明显，但是缺少相关研究。本项目以连作敏感性不同的8个荞麦品种为试验材料，主要研究：（1）分离鉴定不同品种荞麦的根系分泌物，通过对生理生化指标、DNA交联、内源激素含量及比例、化感效应敏感指数等的研究，明确对连作荞麦产生自毒伤害的化感物质；（2）通过对荞麦连作时根际土壤理化特性及速效养分、土壤微生物量及种群结构变化、荞麦的保护酶活性、蛋白质的差异表达、内源激素含量及比例变化等方面的研究，明确根系化感物质对连作荞麦的伤害机理；（3）通过不同密度、肥水及化学调控措施，降低荞麦根际化感物质的浓度和增强荞麦自身对根系自毒物质的抗化感作用，以缓解荞麦的连作障碍。通过上述问题的研究，对于进一步明确荞麦连作伤害的机理，提出改善荞麦连作障碍的技术途径，指导荞麦高产栽培等，均有十分重要的意义。

连作障碍是影响我国荞麦增产的重要限制因素之一，针对这一生产实际问题，本项目系统的研究了根系化感物质对连作荞麦的伤害、连作荞麦的伤害机理、调控措施对荞麦连作伤害的调节作用等，主要结果如下：. （1）根系分泌化感物质通过影响荞麦根际微生物量、地上部株型和产量形成等从而对连作荞麦产生伤害，其中以苹果酸和酒石酸表现明显。. （2）明确了连作荞麦的伤害机理。随连作年限的增加，荞麦根际土壤的速效养分、土壤酶活性以及叶片的叶绿素和可溶性蛋白含量、叶片的SOD、POD、CAT活性呈显著下降趋势，pH值和真菌量显著增加，根际土壤细菌数随连作茬数的增加而先增加后降低。连作显著降低了荞麦的根系长度和表面积和最终的产量。上述研究结果说明连作使荞麦根际土壤性质恶化，肥力降低，形成了特定土壤环境和根际条件，从而影响了土壤及根际微生物的生殖和活动，造成有益微生物数量减少，病原微生物数量增加，严重影响荞麦地下根系和地上部的生长，从而影响营养物质的吸收和干物质的积累，导致产量下降明显，引发连作伤害。. （3）提出了种植密度、肥水管理等栽培措施对荞麦连作伤害的调节作用。当荞麦种植密度为100万株/hm2左右，土壤湿度为20%-25%，氮磷钾肥复合处理时均能明显调节荞麦的连作伤害，提高连作荞麦的产量。. （4）明确了不同化学调控措施（土壤改良剂）对荞麦连作伤害的调节作用。比较分析了混合土壤改良剂、有机土壤改良剂和无机土壤改良剂3种土壤改良剂对连作荞麦伤害的调节作用，发现有机土壤改良剂（成分：作物秸秆、豆科绿肥、腐殖酸、木泥炭、丹宁酸等）通过影响根系分泌化感物质、改善连作荞麦根际土壤性质，进而影响荞麦地上部株型，提高了连作荞麦的产量，值得进一步在生产上推广使用。. 上述研究结果对于明确荞麦连作障碍产生机理，指导荞麦的高产栽培等具有重要的科学和实践意义。. 本项目发表论文19篇，其中SCI收录2篇；申请国家发明专利3件；培养硕士研究生4名；获2017年贵州省科学技术进步奖二等奖1项。