Reduced potassium fertilization combined with magnesium application improves rice population quality and regulates grain yield and quality

Inroduction Sichuan is a major hybrid rice-producing region, where paddy soils commonly suffer from acidification and severe magnesium leaching, resulting in low available-Mg status. Excessive potassium application intensifies K-Mg absorption antagonism and exacerbates magnesium deficiency, while blind potassium reduction accelerates plant senescence and impairs rice yield and quality. Although magnesium participates in photosynthesis and assimilate translocation, little is known about the combined effects of reduced potassium fertilization and magnesium supplementation on rice growth and agronomic performance. Methods A two-year field experiment was conducted to examine rice yield, grain quality, and nutrient uptake under varying potassium-magnesium combinations, aiming to provide fertilization references for green rice production in Sichuan hilly regions. A two-factor split-plot design was employed, with three potassium rates (0, 120, and 180 kg/ ha, denoted K0, K1, and K2) as main plots and three magnesium rates (0, 30, and 60 kg/ha, denoted M0, M1, and M2) as sub-plots. Leaf area index, dry matter accumulation, chlorophyll content, yield components, and grain quality traits were assessed in this study. Results The results showed that the K1 treatment significantly improved grain yield, with relatively better comprehensive performance observed under the K1M2 combination. Averaged across 2 years, K1 increased grain yield by 26.55% relative to K0 and exhibited comparable yield to K2. Under K1, the M2 treatment further increased yield by 6.21% relative to M1. Moreover, K1M2 significantly enhanced leaf area index and chlorophyll content, while improving milling and appearance quality and reducing grain chalkiness and amylose content. Discussion These findings offer a theoretical and practical basis for improving rice yield and grain quality and promoting green, high-quality and efficient rice cultivation in the hilly regions of Sichuan.