【作者】 刘建国；

【导师】 卞新民； 张旺锋；

【作者基本信息】 南京农业大学 ， 作物栽培学与耕作学， 2008， 博士

【摘要】 棉花是重要的经济作物,在新疆绿洲棉区由于棉花种植集中、比重大,导致连作面积大,连作时间长,连作障碍问题突出。本试验对不同连作年限棉田土壤理化和生物性状进行了系统分析,揭示长期连作对棉田土壤环境的影响;从引起连作障碍的化感自毒作用入手,研究棉花秸秆浸提液的化感效应;并且从棉花秸秆浸提液、根系分泌物和不同连作年限棉田土壤中检测出4种酚类化感物质,并进行了对棉花黄萎病病菌生长和棉花幼苗生长影响的验证。主要结论如下:1在新疆棉区,棉花长期连作后,土壤孔隙度增加,土壤容重年平均降低0.0034g·cm^-3,土壤有机质含量随着连作年限延长,增长速率提高,连作后土壤pH值升高,土壤含盐量逐渐增加,土壤有次生盐渍化的倾向。2新疆棉花长期存在重施N肥,轻施P肥,少施或不施K肥的现象。连作后导致土壤中的碱解氮含量显著增加,连作20年土壤碱解氮含量比种植1年增加151.8%,土壤有效磷含量长期连作下降,连作10年后含量较稳定,而有效钾的含量随着连作年限增加显著下降。3随着棉花连作年限增加,残膜量每年平均以11.2 kg·ha^-1速度增加,并且残膜在耕层15-30cm分布比重增大,残膜破碎度加大。残膜在土壤中积累,影响棉花根系生长,使根系发育畸形,但不同根系形态棉花产量间差异不大。4棉花连作5年和10年,土壤过氧化氢酶、转化酶、蛋白酶和中性磷酸酶活性下降,连作年限达到15年、20年时,酶活性又升高;土壤脲酶活性连作10年降至最低,随后缓慢升高;土壤过氧化物酶活性随着连作年限增加而增加。5棉花秸秆水浸提液对小麦、番茄、油菜和苜蓿种子萌发和幼苗生长有一定的化感作用,化感抑制作用强度为苜蓿＞小麦＞番茄＞油菜。棉花具有较强的自毒作用,随着棉花秸秆水浸提液浓度增加,对棉花种子发芽率、胚根长、苗高和侧根数的抑制作用增强,并使棉花幼苗根系活力和根系SOD活性降低,POD活性和MDA含量增加。6在棉花秸秆、根系分泌物和不同连作年限棉田土壤中检测出对-羟基苯甲酸、阿魏酸、没食子酸和香草醛4种酚类化感物质。其中棉花秸秆中的酚类化感物质含量高于根系分泌物中的,棉花秸秆地上部酚类化感物质含量高于地下部。棉花连作1年、5年、10年时土壤中酚类化感物质总量逐年积累,而至连作15年和20年时下降。没食子酸含量随着连作年限增加在土壤中逐渐增加,香草醛在不同连作年限土壤中含量较稳定,而阿魏酸连作5年土壤中含量最高,连作10年时显著下降。7不同浓度的对-羟基苯甲酸、阿魏酸、香草醛和没食子酸对棉花黄萎病病菌孢子萌发和菌丝生长产生促进或抑制的化感作用。不同酚类物质及不同浓度作用效果有一定差异,阿魏酸和香草醛对病菌生长具有低浓度增强、高浓度减弱的“浓度效应”,对-羟基苯甲酸和没食子酸随着浓度增加化感作用增强。8对-羟基苯甲酸、阿魏酸、没食子酸和香草醛4种酚类化感物质对棉花幼苗的根长、苗高和鲜重均有一定的抑制作用,并随着处理浓度的增加抑制作用增强,化感物质对棉花幼苗地上部分的影响比地下部分更敏感。4种酚类物质抑制SOD活性和根系活力,并随着浓度增加抑制作用增强,酚类物质促进POD活性和增加MDA含量。9棉花根系分泌物及秸秆还田分解产生的酚类化感物质可在土壤中积累并与棉花连作障碍有一定关系。更多还原

【Abstract】 Cotton is the most important economical crop in Xinjiang. Along with planting area increasing and continous cropping time extending, continuous cropping obstacles became more common and serious, the sustainable development of cotton production had been seriously restricted. We firstly detected the variation of soil physical,chemical and biochemical properties in response to long-term continuous cotton cropping, illustrated the soil environment effect of continuous cropping cotton simultaneously, The allelopathy of cotton plant extract with the other five kind of crops about cotton, wheat, tomato,rape and alfalfa were studied, then a few allelophathic substances were collected and identified in plant aqueous extract、root exudates and soil of different continuous cropping years. In addition, we also trialed the influence on cotton seedlings and verticillium wilt hypha growth by exterior addition of the four detected phonolic compounds. The main conclusions are as following:1 The soil organic matter’s content and the soil porosity were increased because of long-term continuous cotton cropping, but its Bulk Density was reduced by an average0.0034 g. cm^-3, the soil salt content and pH slightly were also raised, which led to the soil structure meliorate.2 Along with the continuous cropping year increasing, the soil Alkali-hydrolyzable N content was remarkably raised,its content of 20 years continuous cotton cropping was increased by 151.8% , the soil Available P was first fell and then stable in 10-year continuous cotton cropping, but the soil Available K was remarkably increased by straight line.3 The content of residue film was increased by average 11.2 kg.hm（-2） a year and residue film mostly distributed in underlayer （15-30cm） of tilth, the shatter ratio of residue film was enhanced owing to increasing continuous cropping years. The residue film in soil can inhibit the vertical growth of the cotton roots,and force its to form okra roots and cluster roots, but cotton yield weren’t affected.4 The activities of catalase、protease、invertase and phosphatase were decreased in 15-20 years continuous cropping, but those enzyme activities were increased in 15-20 years continuous cropping; The soil urease activity was the most declined in 10 years continuous cotton cropping, and then slowly increased; The soil peroxidase activity was increased with the continuous cropping year increasing.5 There had allelopathic effect of cotton plant aqueous extract and affected seed germination and seedling elongation of wheat, rape, tomato and alfalfa, the sequence of material allelopathy was alfalfa >wheat>tomato>rape.The autotoxic effect of cotton extract intensly affected cotton seedlings, and had a promoting effect on germination percentage, root length, shoot high and number of root as cropping intensity added , meahwhile SOD activities and root activities of cotton seeding were lessened, and POD activities and MDA content were enhanced.6 The main components of root exudateand and plant aqueous extract were identitified as p-hydrobenzoic, vanillic, gallic acid and ferulic acids by HPLC. Their contents in plant aqueous extract were more than that of root exudate. Four phenolic components of p-hydrobenzoic, vanillic, gallic acid and ferulic acids could be detected in soil with different continuous cropping years. The total contents of four allelopachimicals in soil were showed a stepwise accumulation from continuous cropping 1 year to 10 years, but failed in fifteen and twenty.The detected phenolic, gallic acid was gradually increased with continuous cropping years increasing, vanillic was steady in soil of different continupus cropping years, ferulic acids had more content in soil of five-year continuous cotton cropping, but remarkably reduced with ten-year continuous cropping.7 It was found that the p-hydrobenzoic, vanillic, gallic acid and ferulic acids in different comentration inhibited/stimulated the spore germination and mycelium growth of cotton verticillium wilt. It is discrepant in different allelochemicals and concentration, low concentration of the ferulic acids and vanillic could stimulate the growth of verticillium hypha, while at hight concentration, the growth vigor was restrained. The inhibitory effect of p-hydrobenzoic and gallic acid were enhanced with increasing concentration.8 The p-hydrobenzoic, vanillic, gallic acid and ferulic acids affected root length,shoot height and fresh weight of cotton seeding, Inhibition effect was raised with the comcntration increasing. The sensitivity of allelochemicals was different with the different parts of coton seedlings.The root sensitivity was higher than that of above-ground of seedlings. When cotton was dealt with different concentrations of the same allelochemical, SOD and root activity were decreased , MDA content and POD activity were increased with the concentration increasing.9 The allelochemicals from root exudateand and plant extract were accumulat into soil, and was related to continous cropping obstacle of cotton.更多还原