Effects of nitrogen levels of jujube-cotton intercropping system on physiological characteristics of cotton leaves in different positions

This experiment was conducted in order to study the physiological characteristics of functional axial leaf and branch leaves as affected by applying different levels of nitrogen fertilizer: pure N 0 kg·hm2(N0),207 kg·hm-2(N30),310 kg·hm-2(N45);414 kg·hm-2(N60),using common cotton variety CCRI49.The Results were as follows:(1) Nitrogen deficiency lead to decrease of leaf area index,SPAD,leaf physiological index(NR,the content of soluble protein and soluble sugar),especially in functional axial leaves.(2) NR activity would fall fast at later full boll stage and the content of soluble protein,soluble sugar accumulated excessively when excess nitrogen fertilizer were used which was harmful.(3) The shaded cotton and the non-shaded cotton had higher yield under N30 treatment and N45 treatment,respectively.It showed that shading reduced the absorbition of Nitrogen.In this experiment,the nitrogen application rate among 207～310 kg·hm-2 could keep a blance carbon-nitrogen metabolism level and prevent early senescence under light-nitrogen interaction system.