Effects of Nitrogen Supply on Yields and Photosynthesis Characteristics of Crops in Wheat and Broad Bean Intercropping

Rational intercropping can improve the photosynthetic efficiency and yield of the crops, the application of nitrogen fertilizer have an impact on photosynthetic efficiency of legume-gramineae intercropping crops. In order to understand the influence on photosynthesis characteristic of crops and yields under the condition of intercropping and the application of different nitrogen fertilizer rates (N0 0 kg/hm2, N1/2 90 kg/hm2, N1 180 kg/hm2, Nsub>3/2 270 kg/hm2), a field experiment was conducted. The results showed that wheat, broad bean intercropping had significant advantage to over-yielding, land equivalent ratio LER under N0, N1/2 and N1 level were 1.12,1.09 and 1.06,respectively, which were disappeared along with the application of nitrogen fertilizer increased (N3/2, LER=0.98).Compared with the monoculture, the production of wheat under the intercropping system improved significantly, under N1 and N3/2 level, increased 40.02% and 30.83%, respectively. The net photosynthetic rate, transpiration rate, intercellular CO2 concentration increased along with the decrease application rate of N in intercropping; net photosynthetic rate, transpiration rate, intercellular CO2 concentration reached maximum in the N1/2(wheat transpiration rate reached the maximum in N1). In N1 and N3/2 level, intercropping significantly reduced intercellular CO2 concentration of wheat, decreased by 32.23% and 41.67%; the transpiration rate reached the maximum in N1/2 in intercropping system. In N1 and N3/2 level, transpiration rate of intercropping faba bean significant differences compared with the monoculture, decreased by 30.85% and 44.48%. Intercropping faba bean intercellular CO2 concentration in the N1/2 was the maximum, and it was significant difference in N1 between monoculture and intercropping, increased by 31.30%. Overall, intercropping and fertilizer have a promoting role on crop yield, biomass and photosynthetic characteristics.