Effects Of Density And Nitrogen Fertilizer On Cotton Production And Nitrogen Utilization

With the shortage of picking labor and the rising cost of picking cotton,mechanical harvesting has become an inevitable requirement for the sustainable development of cotton in Xinjiang.However,the agronomic techniques matching with mechanical harvesting of cotton have not been completely established.Cotton planting density and nitrogen application are key technical measures affecting the yield of machine harvested cotton.This article takes No.54 in the new land as the tested variety,field split plot test was conducted in Awati County,the main cotton producing area in southern Xinjiang.The main area for the 2planting density of 180 thousand plants/hm²（D18）,240 thousand plants/hm²（D24）.The sub area is 4nitrogen application amount 0 kg/hm²（N0）,170 kg/hm²（N1）,320 kg/hm²（N2）,470 kg/hm²（N3）.The effects of density and nitrogen fertilizer on growth and development,yield formation,canopy structure,photosynthetic characteristics,dry matter and nitrogen accumulation and distribution of nitrogen fertilizer and nitrogen fertilizer utilization were carried out under the（66+10）cm one film and six row planting pattern.The effects of density and nitrogen fertilizer on yield and nitrogen use of machine picked cotton were discussed.The main conclusions are as follows:1.The effects of density and nitrogen fertilizer on cotton growth and yieldUnder the same planting density,with the increase of nitrogen application rate,plant height,true leaf number,inverted Mitsuba Hiroshi,fruit branch number and stem diameter increased.Under the same amount of nitrogen application,the agronomic traits decreased with increasing density.The increase of planting density and nitrogen application will prolong the growth period of cotton.Under the condition of D18 density,the boll number per plant,single boll weight,lint percentage,seed cotton yield and yield increase increased with the increase of nitrogen application rate.Under the condition of D24 density,the trend is first increasing and then decreasing.The yield and nitrogen use efficiency of cotton treated by D24N2 were the highest,50.68%and 6.38 kg/kg respectively.2.The effects of density and nitrogen fertilizer on Photosynthetic and Canopy Properties of cotton woolUnder the same planting density,with the increase of nitrogen application rate,LAI,leaf temperature and Tr increased,expressed as N3>N2>N1>N0.Under the same amount of nitrogen application The LAI,blade temperature and Tr of D18 are higher than D24.Under the condition of D18 density,with the increase of nitrogen application,the contents of Pn,chlorophyll a,B,a+b and Q showed an increasing trend.The performance of Amax,LSP and Rd was increased first and then descended.Under the condition of D24density,all the above traits increased first and then decreased.D24 is 12.08%higher than that of LAI under LAI treatment.The increase of chlorophyll a+b in the middle of the crown of the canopy is 5.84%.The maximum net photosynthetic rate of D24N2 was 36.54 mol m^-2 S^-1 and the range of light energy utilization was wide.3.The effects of density and nitrogen fertilizer on dry matter and nitrogen accumulation and nitrogen distribution in cotton productionUnder the condition of D18 planting density,with the increase of nitrogen application,the proportion of total dry matter accumulation and dry matter accumulation in reproductive organs increased.Under the condition of D24 planting density,with the increase of nitrogen application,Increase of dry matter accumulation in population.The proportion of dry matter accumulation of reproductive organs in the open season was first increased and then decreased.Increasing the planting density under the same amount of nitrogen application.Population dry matter accumulation and population nitrogen accumulation increased.Two under the condition of planting density,nitrogen absorption and utilization rate and nitrogen recovery rate first increased and then decreased,showing N2>N3>N1.The partial production rate and nitrogen dependence rate of nitrogen fertilizer showed a decreasing trend,showing N1>N2>N3.Under the same nitrogen application conditions,with the increase of density,the uptake utilization rate of nitrogen fertilizer increased.Nitrogen fertilizer partial productivity,nitrogen dependence rate and nitrogen fertilizer recovery took the lead in increasing and descending.The dry matter accumulation of D24 increased by 22.81%,compared with that of D18 group,and the nitrogen accumulation of population increased by 10.90%.D24N2 had more dry matter accumulation than the D18N3 during the boll opening period,and the nitrogen uptake and utilization rate was 14.21%higher than that of the 34.35%.In summary,in the Akesu area of Southern Xinjiang,when the planting density is 240 thousand/hm²and the nitrogen application is 320 kg/hm²,the yield is higher,the utilization rate of nitrogen fertilizer is the highest,the agronomic traits conform to the standard of the cotton production,the photosynthesis performance is strong,the canopy structure is reasonable,the accumulation of dry matter and nitrogen is more,and the proportion of the distribution ratio in the reproductive organs and the camping organs is balanced.