Effect Of Nitrogen Levels On Photosynthetic Production And Boll Development Of Cotton Under Shading Conditions

Fruit and cotton intercropping changed the cotton monoculture layout, became acomplex dimensional cultivation model, by changing the cotton field microclimate, affectedthe growth, yield and quality of cotton, etc. In order to achieve the purpose of increasing yieldand enhancing quality，the rational application of nitrogen fertilizer could be used to controlthe growth of cotton in production. This test simulates fruit and cotton intercroppingconditions, set different nitrogen levels, to study the mechanism of nitrogen levels on cottongrowth, playing an importing role in determining the intercrop fields’ reasonable amount ofnitrogen fertilizer. The main conclusions are as follows:1. In shading conditions, cotton growing process goes backward, with increasing amountof nitrogen, cotton flower and boll stage to extend, the boll opening late, eventually leading tothe increase in the proportion of cream flowers, the effectively number of bolls reduced. Plantheight, plant width, down four leaf width has increased, when nitrogen rate is320kg/hm²,cotton catch a compact plant type，the canopy structure is reasonable，could catch more lightenergy.2. In shading conditions, cotton leaf net photosynthetic rate decline by non-stomatafactors, When the nitrogen rate is320kg/hm², elevated chlorophyll content, improve the rateof leaf transpiration, stomatal conductance, Fv/Fm, ΦPSⅡ, qP reduce intercellular CO₂concentration and NPQ，PSⅡreaction center is fully open to absorb more light energy forphotochemical delivery, improve the conversion efficiency, improve the performance of leafphotosynthesis, Pn increased, higher dry matter production capacity.3. In shading conditions, when nitrogen rate is320kg/hm², get a higher reproductiveorgans accumulation and dry matter accumulation，a higher reproductive organs nitrogenaccumulation, is conducive to the formation of yield and quality. Nitrogen rate is too high,vegetative organ leggy, to the detriment to the production and the distribution of nitrogen in the vegetative organs, is not conducive to the boll and fiber development.4. In shading conditions, yields reduced by31-40%, when nitrogen rate is320kg/hm2, tomaintain high volt peach proportion the proportion of peripheral bell, fiber biomass,effectively bolls per plant and boll weight significantly increased yield increased byapproximately64%, and improve the quality of the fiber, increase the fiber length andstrength, micronaire value in the optimum range.