Study On The Allelopathy Of Cotton And Cumin Intercropping Pattern By Cotton Root Exudates

Cotton is a economic crops in Xinjiang, since the continuous cropping time is long and the cultivatedarea is large, there are a series of negative effect, which caused continuous cropping questions of cottonin Xinjiang to be prominent. it is of great significance to the sustainable development of southern xinjiangeconomy to explore the role of cotton growth from allelopathic effect. Bioassay and physiologicalexperiment were adopted to explore the allelopathic effect and mechanism of cotton on several plantreceptors. Effects of cotton and cumin intercropping on the soil microorganisms, enzyme activities andquantitative of three Phenolic compounds were researched. We provide academic evidences for diclosingcontinuous cropping obstacle and founding efficient rational cultivate system. The main results are asfollow：1、The water culture method was used to collect cotton root exudates. Effects of allelopathy of cotton rootexudates on different receive crops were researched at different stages(cultivated for10d,20d,30d)through seed germination and seedling growth experiments. The results indicated: cotton root exudates hadallelopathic effect on peppers, corn, cabbage, radish, tomato and cotton itself had autotoxicity, itsinhibition effected gradually strengthens with increasing concentration; cotton root exudates inhibitted oraccelerated seed germination, seedling growth and enzyme activity of plant receptors. Growth indexes ofplant receptors increased at low concentrations but decreased at high concentrations of cotton root exudates.And cotton root exudates had stronger inhibition effect to plant radicle than stems and leaves. cotton rootexudates had stronger inhibition to corn，but the inhibition was weaker to others.2、The results showed that compared with monoculture, the amount of bacteria, fungi, actinomycetes,ammonifiers and aerobic azotobacter in soil were decreased under intercropping pattern, and cottonmonoculture＞cotton/cumin intercropping＞cumin monoculture. The number of bacteria andactinomycetes presented the change trend which deereased with the increasing of the intercroppingcropping years, and fungi, ammonifiers and aerobic azotobacter quantity were not affected by intercroppingcropping years.3、In different rotation patten, soil enzyme activities showed that cotton monoculture＞cotton/cuminintercropping＞cumin monoculture, it consistented with the change trend of soil microbial quantity, and thesoil urease, catalase, sucrase and protease activities under other intercropping patterns was very prominencethan cotton monoculture, except the soil peroxideenzyme activitie under one year and two yearscotton/cumin intercropping.The relationship between soil microbial quantity and soil enzyme activities waspositive correlation, the Pearson correlation coefficient was that: urease＞sucrase＞catalase＞protease＞peroxideenzyme. 4、 Three phenolic acids of cotton’s soil in different rotation patten were estimated throughhigh-performance liquid chromatography methods, they were gallic acid, p-hydroxybenzoic and ferulicacid. Their contents in cumin monoculture were more than cotton monoculture and cotton/cuminintercropping, and cotton and cumin intercropping could significantly reduce the contentof p-hydroxybenzoic, but the content of Gallic acid and ferulic acid were not much differencebetween cotton monoculture and cotton/cumin intercropping.