Nitrogen (N) is one of the most important nutrients determining crop growth performance. With the increasing demand for sustainability in global agriculture, improving nitrogen use efficiency in rice has become a critical issue. Nitrogen use efficiency (NUE) in rice is a complex trait influenced by multiple factors, among which phytohormones play a key role. NUE is primarily regulated through the influence of phytohormones on absorption, transport, assimilation, and utilization processes. In this review, we focus on these interactions and summarize the relationships between major hormones and nitrogen use efficiency in rice. Finally, we outline the current challenges and future research prospects in this field. Although studies have shown promising results for their role in improving crop NUE, the specific mechanisms remain unclear. Additionally, the interactions among phytohormones and the influence of environmental factors on their effectiveness require further investigation. This review provides theoretical support and technical guidance for understanding the role of phytohormones in rice NUE and offers insights into improving NUE in rice.

Weedy rice (Oryza spp.) has become one of the most harmful weeds in rice fields worldwide. It is a conspecific plant of cultivated rice (Oryza sativa L.) belonging to the genus Oryza, widely occurring in global rice production systems with a cosmopolitan distribution across major rice-growing regions. Due to its unique biological characteristics, such as strong environmental adaptability, stress resistance, seed shattering propensity, seed dormancy, and competitive dominance, weedy rice can rapidly proliferate and persist in fields, posing a severe threat to rice production systems. This review summarizes the current research progress on the biological characteristics of weedy rice and introduces the significant differences in biological characteristics between weedy and cultivated rice, such as phenotypic diversity, seed shattering, dormancy, strong competitiveness, stress resistance, and early maturity. These distinct biological traits, which significantly differ from cultivated rice, serve as essential mechanisms in the survival strategy of weedy rice. Our review will provide a theoretical reference for a deeper understanding of weedy rice and its integrated management.