Breeding Rice Varieties for Low Nitrogen Environments

Nitrogen is an essential nutrient for rice growth, but the excessive use of nitrogen fertilizers has led to environmental degradation, increased costs, and diminishing returns. Root structure and the ability to maintain chlorophyll content are key indicators of nitrogen use efficiency (NUE), while genes such as OsTCP19 , OsNAC68 , and TOND1 play important roles in nitrogen uptake and assimilation. Field and hydroponic trials, combined with high-throughput phenotyping technologies, are effective in evaluating genotypic variation and selecting superior varieties. Breeding strategies include conventional selection, marker-assisted selection (MAS), genomic selection (GS), and the introgression of favorable traits from wild or traditional rice varieties. The case of Swarna-Sub1 demonstrates the potential of integrated breeding for enhancing both stress resistance and NUE. Despite significant progress, breeding efforts still face challenges such as balancing high yield with NUE, shortening breeding cycles, and adapting to diverse ecological zones. Integrating genetic improvement with sustainable agronomic practices—such as precision fertilization and organic fertilizer application—can reduce nitrogen input while maintaining yield, offering a promising path toward green, economical, and efficient rice production.