Effects Of Nitrogen Fertilization On Jujube-cottonintercropping System Cotton Root Growth And Yield

Cotton (Gossypium hirsutum) is an important economic crops in our country and even in the world.Nitrogen plays vital role in cotton root growing, determine the reasonable nitrogen fertilization, improvethe utilization rate of nitrogen, reduce the use of nitrogen fertilizer to the environment pressure is the mosturgent solved problem. Jujube-cotton intercropping system is one of the major composit ecosystem inagriculture and forestry intercropping mode, However, jujube trees could make shading effect, affect thenormal growth and development of root and eventually to decline the yield and quality of cotton; Nitrogenand light as corps tow most growth factors, illumination shortage caused by intercropping and nitrogeninteractively affect the plant root growth and distribution of material, and dry matter distribution and yieldquality.In this research CCRI49as experimental material, through the research of jujube-cotton intercroppingconditions in different levels [0（N0）、150（N10）、450（N30）and750（N50）kg/hm2] of nitrogen, effectto the cotton root morphology and physiological index and yield quality, explains the response mechanismof cotton in different nitrogen fertilization, determine the jujube-cotton intercropping reasonablefertilization, for the jujube-cotton intercropping planting mode in reasonable nitrogen application, improvethe yield and quality will be provide a theoretical basis. The results are as follows:1. Nitrogen fertilization improve the cotton root length, when use the N30treatment there are longestroot length, explains the reasonable nitrogen fertilization will promote the growth of cotton root system,when provide different level N there are significant effect to the cotton root length, between treatmentdifference is N30>N10>N0>N50.2. The cotton dry matter and nitrogen accumulation in different treatment is fit the Logistic equationand there was a significant difference in dry matter accumulation of cotton on different nitrogenfertilization. Nitrogen deficiency or excess will be effect the dry matter accumulation and distribution indifferent growth period, the yield reduction and effect of cotton quality. In each treatment dry matter rapid accumulation duration close and far area difference are N30>N10>N0>N50.3. Reasonable nitrogen fertilization will be significantly improve the root vigor, soluble proteincontent, soluble sugar content and NR activity of jujube-cotton intercropping system. A change of rootvigor is the most significant. In the early developmental period of cotton, the close area respectivelydecrease41.5%、27.1%、33.7%, far area respectively decrease36.1%、18.7%、26.7%, explain the nitrogennutrition deficiency will accelerated the senescence of cotton root, inhibited the root growth anddevelopment; therefore, reasonable nitrogen fertilization, can delay the senescence of root system.4. Under jujube-cotton intercropping conditions reasonable nitrogen fertilize regulation not only canguarantee the increase of boll numbers and boll weight, thus improve the yield, close area needs less than fararea to the N fertilizer when it high yield.。The proper nitrogen fertilizer can improve the cotton fiber quality;Optimization nitrogen management measures can significantly improve the fiber length and specific strength.And to ensure that the micronaire value in the best quality range, but for the elongation and uniformity hasnot effect. N deficiency to affect the specific strength and micronaire value. Shadow will decrease the fiberbreak specific strength, fiber elongation, maturity and micronaire value. For the influence degree ofintercropping on cotton fiber quality, the upper and lower part effects stronger than middle part. Under thejujube-cotton intercropping conditions the nitrogen fertilization at the [450（N30）Kg/hm2] level will obtainbetter dry matter accumulation and increase production effect.