Response of nitrogen accumulation, yield, and quality characteristics of peanut varieties with different nodulation traits to nitrogen fertilizer application rate

Reducing nitrogen (N) application is an effective strategy for enhancing N use efficiency and promoting the N-fixing capacity of peanut root nodules. Given the considerable variation in nodulation traits among peanut cultivars, this study aimed to compare N absorption and utilization between common nodulating variety (CNV) and non-nodulating variety (NNV). A two-year field experiment was conducted across three locations in Shandong, China, to evaluate the responses of CNV and NNV to N fertilizer application rates of 120, 60, and 0 kg hm-2, focusing on N accumulation, N use efficiency, yield, and quality. The results showed that reduced N fertilization significantly decreased N content, N accumulation, yield, and kernel protein content in NNV. Compared with the N120 treatment, the N60 treatment resulted in average reductions of 18.98% in whole-plant N accumulation, 17.30% in yield, and 10.69% in kernel protein content, while the N0 treatment caused average reductions of 25.13%, 13.97%, and 11.40%, respectively. In contrast, CNV maintained relatively stable N accumulation, yield, and kernel protein content across all N levels. Pearson correlation analysis revealed significant positive correlations between N accumulation in various plant organs and both yield and kernel protein content in NNV, whereas no such correlations were observed in CNV. These findings demonstrate that NNV is more sensitive to N fertilizer in terms of yield, quality, and N accumulation than CNV. Therefore, appropriately reducing N fertilizer input in peanut cultivation may enhance the utilization of biological N fixation by root nodules, thereby improving overall N use efficiency.