Physiological Characteristics of Nitrogen Nutrition in Peanut and Efficient Nitrogen Application Technology

Nitrogen plays a very important role in peanut nutrition and fertilization. For peanuts, the nitrogen nutrition comes from root nodules, soil and fertilizer, which are separately referred to as root nodule nitrogen, soil nitrogen and fertilizer nitrogen. The research obtained following findings. (i) The nitrogen supply ratio of the three nitrogen sources for peanut is about 5:3:2. There are significant differences in the nitrogen supply capacity of the three nitrogen sources. The root nodules have the largest variation in nitrogen fixation and have a high potential for development. Nitrogen fixation in root nodules is closely related to carbon metabolism indicators such as photosynthesis in peanut leaves. Phosphorus application could increase the accumulation of three nitrogen sources, and the increase in nodule nitrogen accumulation is greater than that of soil nitrogen and fertilizer nitrogen. (ii) Nitrogen fertilizer has a significant effect on nitrogen nutrition of peanuts. Different forms of nitrogen fertilizers, such as amide nitrogen, ammonium nitrogen, nitrate nitrogen and mixed ammonium nitrate nitrogen, have significant effects on nitrogen metabolism and nitrogen accumulation in peanuts. Amide nitrogen fertilizer is beneficial to improving the activity of enzymes related to nitrogen metabolism and nitrogen accumulation. Controlled-release fertilizer can significantly increase the content of soluble protein and improve the activities of NRase, GDH, GS, GPT, etc. in roots and leaves at the pod setting and mature stages of peanuts, which is favorable for delaying the plant senescence and increasing the yield of peanuts. Mixed application of common nitrogen fertilizer and slow-release fertilizer can increase the soil nitrate nitrogen level at the later growth stage, which is beneficial to the development of the root system at the later stage of growth, increasing the distribution ratio of nitrogen in the pods, and also favorable for increasing the yield and nitrogen utilization rate. (iii) Increasing the ploughing depth, improving fertilization methods, selecting nitrogen-efficient varieties, paying attention to foliar topdressing, and adopting fertilizer-water integrated cultivation are conducive to increasing the nitrogen utilization rate of peanuts, reducing the amount of nitrogen fertilizers, accordingly saving costs, increasing efficiency and realizing sustainable development of agricultural production.