Effects of different nitrogen levels on iron nutrition and nitrogen fixation of peanut in maize-peanut mixed cropping system

Maize-peanut mixed cropping could obviously improve iron nutrition of peanut under different nitrogen levels in pot experiment. Compared with sole cropping peanut, not only the chlorophyll SPAD value was (increased), but also active iron concentration was increased by 12.4%—27.1% in young leaves of mixed cropping peanut, at the same time the excisable nodule number and nodule nitrogenase activities (ARA) per plant peanut also were increased significantly. Both the nitrogen level and planting pattern had no great effect on peanut dry weight in this experiment. The more nitrogen fertilization could increase active iron concentration in the rhizophere of maize, but inhibit excisable nodule number and nitrogenase activities of peanut. The results showed that maize-peanut mixed cropping played an important role in improving iron nutrition and nitrogen fixation function of peanut on calcareous soil. The different nitrogen levels had no great effect on iron nutrition of peanut, but it restrained symbiotic nitrogen fixation of peanut with nitrogen application increase.