油棉两季秸秆还田下施氮量对棉花产量形成及氮肥利用效率的影响

Effects of Nitrogen Application Rate on CottonYieldFormation and Nitrogen Utilization Efficiency underRape-Cotton Double Cropping Straw Returning Condition

基于油―棉两熟种植模式,为探究油菜、棉花秸秆还田条件下施氮量对棉花产量形成及氮素吸收利用的影响。设置6个处理,T1为秸秆不还田+施氮180 kg/hm^(2),T2~T6为在秸秆还田基础上分别施氮0、60、120、180和240 kg/hm^(2)。结果表明,秸秆还田条件下,施氮可以提高花铃期叶面积指数,从而提高棉花群体光合性能,进而提高棉株干物质积累量及铃数和铃重等产量性状,籽棉产量以180 kg/hm^(2)的施氮量最高;氮肥的农学利用率和回收利用率随着施氮量的增加而降低,施氮量分别为120和180 kg/hm^(2)时下降显著。在施氮量相同(180 kg/hm^(2))条件下,与秸秆不还田相比,秸秆还田籽棉增产7.7%,并且显著提高了氮肥的农学利用率和生理利用率。综合棉花生长发育及氮素吸收利用情况,在油棉轮作系统中油菜、棉花秸秆全量还田下,棉田可适量减少肥料氮投入,以120~180 kg/hm^(2)为宜。

Based on the rape-cotton double cropping model,in order to explore the effects of nitrogenapplication rate on cotton yield and nitrogen absorption and utilization under the condition of rape andcottonstraw returning,six treatments were set,T1 was no straw returning+N 180 kg/ha;T2-T6 refered to nitrogenapplication of 0,60,120,180 and 240 kg/ha on the basis of straw returning.The results showed that under thecondition of straw returning to the field,nitrogen application could improve the leaf area index at floweringandboll stage,thereby improving the population photosynthetic performance of cotton,and further improvingthedrymatter accumulation of cotton plants.The boll number and boll weight and other yield traits,seed cottonyieldwere the highest under the nitrogen application level of 180 kg/ha.The agronomic utilization rate and recoveryrate of nitrogen fertilizer decreased with the increase of nitrogen application rate,and decreased significantlywhen the nitrogen application rate were 120 and 180 kg/ha,respectively.Under the same nitrogen applicationrate(180 kg/ha),compared with no straw return,straw returning increased the yield of seed cotton by 7.7%,andsignificantly improving the agronomic and physiological utilization rates of nitrogen fertilizer.Basedonthegrowth and development of cotton and the absorption and utilization of nitrogen,under the conditionof full returning of rape and cotton straw in the rape-cotton rotation system,the input of fertilizer nitrogen in cottonfieldcan be reduced appropriately,and 120-180 kg/ha was appropriate.