Rice (Oryza sativa L.) is a staple food for more than half of the world’s population, and enhancing its yield and productivity is crucial for global food security (Sharif et al., 2014). Rice yield is not determined by a single genetic or environmental factor but emerges from the complex integration of internal signaling networks and external cues. Among these, light and photosynthetic products (carbohydrates) are the primary drivers of plant growth and development (Li et al., 2025). Light perception through various photoreceptors initiates signaling cascades that regulate key developmental processes, including plant architecture and the critical transition to flowering. Concurrently, photosynthesis converts light energy into chemical energy, producing sugars that serve as both essential metabolic substrates and potent signaling molecules.

Nitrogen stands as the most pivotal mineral nutrient governing crop productivity, serving dual roles as both a fundamental structural component and a dynamic regulatory signal. As a building block, it constitutes essential biomolecules including proteins, nucleic acids, chlorophyll, and hormones, thereby underpinning virtually every aspect of plant growth, from photosynthetic efficiency and energy metabolism to cell division and biomass accumulation. Beyond its structural contributions, nitrogen also functions as an intrinsic signaling molecule, modulating transcriptional networks and coordinating developmental programs that influence key yield-related traits, including tillering, flowering time, grain formation, and resource allocation.

Crop yield is fundamentally governed by the balanced coordination of photoassimilated carbon and nitrogen, a macronutrient indispensable for plant development. Photosynthetic capacity is intrinsically linked to leaf nitrogen content, with plants typically allocating about 75% of leaf nitrogen to chloroplasts to support photosynthetic processes (Evans, 1989). Conversely, efficient nitrogen assimilation relies on robust photosynthetic activity, as the products of photosynthesis, such as carbon skeletons from photoassimilates, along with ATP and NADPH, are indispensable for nitrogen metabolism (Poorter and Evans, 1998; Li et al., 2021; Guan et al., 2025). Furthermore, light can directly regulate nitrogen uptake and metabolism by promoting the shoot-to-root translocation of the transcription factor ELONGATED HYPOCOTYL5 (HY5) (Chen et al., 2016). Thus, crop yield is fundamentally shaped by the assimilation of photoassimilates and nitrogen, as well as the efficient translocation of photosynthates from source tissues to sink organs (Wang et al., 2025a). This review summarizes current understanding of how light and sugar signaling pathways converge with nitrogen utilization to regulate rice productivity. We examine the roles of photoreceptors and sugar transporters, explore the central regulatory networks that sense and transduce energy and nutrient status, and highlight how transcription factors coordinate these inputs to maximize yield. This deeper mechanistic insight positions the elucidated signaling crosstalk as a holistic framework for next-generation breeding strategies to develop high-yielding rice with superior resource-use efficiency.