Effects of different nitrogen levels on photosynthetic characteristics,dry matter accumulation and yield of relay strip intercropping Glycine max after blooming

In the relay strip intercropping system of Zey mays-Glycine max,the G.max cultivar,Gongxuan 1,was used to study the effects of different nitrogen levels on photosynthetic characteristics,dry matter accumulation and yield of G.max after blooming.The results showed that the optimal treatment on the Chl a content,Chl a/b ratio,net photosynthetic rate(Pn),the dry weight of leaf blade,leaf stalk,stem and pod and the total above-ground biomass after blooming was the lower nitrogen level(32.4 kg/ha),followed by the middle nitrogen level(64.8 kg/ha).The optimal treatment on the yield and number of pods was also the lower nitrogen level,which were 18.22% and 17.37% higher than those in the controls respectively,the difference was very significant;followed by the middle nitrogen level;those of the higher nitrogen treatment(97.2 kg/ha) were significantly lower than those in the controls,which was due to the higher leaf area index(LAI) for high nitrogen treatment to result in hindering ventilation and transmission light.So,the appropriate nitrogen(32.4,64.8 kg/ha) could improve the net photosynthetic rate(Pn) and the total above-ground biomass,accordingly improve yield.