Characteristics of nitrogen accumulation and utilization in peanuts (Arachis hypogaea) with different nitrogen use efficiencies

Enhancing nitrogen (N) use efficiency at a genetic level would be an effective way to reduce N use and strive toward green cultivation. Understanding the N use characteristics of different peanut (Arachis hypogaea) varieties could provide some valuable insight for selecting and breeding peanut varieties with high N use efficiency and reduce applied N use in cultivation. In total, 19 peanut varieties were used to investigate the N accumulation and utilization characteristics under different N use efficiency conditions of varieties with differing yield potentials in a pot experiment via ¹⁵N isotope tracing analysis. Based on the average yields and N use efficiencies, the 19 peanut varieties were divided into the following four types:high yield and high N use efficiency (HYHN), high yield and low N use efficiency (HYLN), low yield and high N use efficiency (LYHN), and low yield and low N use efficiency (LYLN). The results showed that there were significant differences in different peanut varieties. The varieties with moderate N content in the vegetative organs were conducive to a simultaneous increase in the yield and N use efficiency, while no significant differences were detected in the N content of the reproductive organs or whole plants across various peanut varieties. Increases in the N allocation rates in reproductive organs were characteristic of the HYHN varieties under the assumption that there was sufficient N accumulation in the peanut plants. The results also showed that the available N levels and N use efficiencies of the soil's N source and fertilizer's N source were consistent in various peanut varieties, whereas different yields among the varieties determined the fixed N from the N source at nodulation. In addition, under similar N use efficiency conditions, a higher N-fixing nodule level favored increased yield. The N supplying from the soil's N source increased in the high-N type varieties compared with that in the low-N type varieties; however, it was the opposite with regards to the fixed N source at nodulation. This showed that were desirable compensatory effects between the soil's N and fixed N sources. Meanwhile, there were no significant differences in the N supplying ratios with regards to the fertilizer's N source in various varieties. The yields and N use efficiencies of different varieties were highly consistent with the N use efficiency and partial productivity of the N fertilizer, whereas there were negligible differences in the N use efficiencies among various peanut varieties. In conclusion, there were significant differences among different peanut varieties with respect to the yield and N use efficiency. Breeding a HYHN peanut variety is of great importance and appears feasible. This is an effective method to decrease the N use in peanut cultivation in the future.