The Influence of Nitrogen Fertilizers on Endophytes in Rice Grains and Rice Quality

Abstract

This study investigated how nitrogen (N) fertilization influences rice grain quality and seed endophytic microbial communities, a topic of growing importance because of the critical role of N management in balancing crop productivity and nutritional attributes. Four N treatments were applied: no N (N0), low N (N1), normal N (N2), and high N (N3). The results showed that increasing N application significantly elevated amino acid and protein contents but reduced taste values. Microbial community structure was highly responsive to N levels, with Proteobacteria and Ascomycota as the dominant phyla. High N treatment notably enriched Mucoromycota, which correlated positively with amino acids and protein and negatively with taste. Co-occurrence network analysis revealed that high N increased microbial OTUs (64 bacterial and 50 fungal) and interactions, enhancing ecological network stability. Functional predictions suggested that N indirectly affects grain quality by modulating microbial metabolic processes such as heterotrophy. These findings demonstrate that N fertilization reshapes the seed microbiome, thereby influencing rice nutritional and sensory quality, and provide insights for optimizing N management to improve rice quality.