Calcium application synergistically enhances yield and nutritional quality in waxy maize

Introduction Optimizing the yield and nutritional quality of waxy maize is essential to meet evolving consumer demands and ensure food security. Calcium plays a vital role in plant physiology, but its foliar application effects on the synergistic improvement of yield and kernel nutritional traits across diverse waxy maize hybrids remain underexplored. Methods This study investigated the effects of foliar-applied calcium chloride (CaCl ₂ , 18 mmol/L, applied at the V12 stage) on 36 hybrid varieties of waxy maize. Agronomic traits, photosynthetic parameters, and grain nutritional components were measured and analyzed. Results The treatment slightly suppressed plant and ear height, but significantly increased ear length, ear diameter, and fresh weight per ear. Photosynthetic analysis revealed that 34 out of 36 hybrids exhibited a significant increase in net photosynthetic rate (ranging from 4.5% to 230%), while two hybrids showed non-significant increases. SPAD values showed non-significant increases, suggesting that calcium enhanced the operational efficiency of the photosynthetic apparatus rather than chlorophyll content. Concurrently, the treatment significantly enhanced kernel nutritional quality. Soluble sugar content increased by 1.1–17%, crude protein by 1.5–24.8%, and key micronutrients—zinc (2.7–13.8%), iron (1.7–15.4%), and calcium (1.6–15.3%)—were significantly elevated. Correlation analysis revealed that soluble sugar content was highly significantly and positively correlated with ear length and diameter, and that increases in soluble sugar and protein were significantly associated with micronutrient accumulation. Discussion These findings indicate that exogenous CaCl₂ optimizes source–sink balance by improving photosynthetic efficiency and assimilate partitioning, thereby driving a synergistic enhancement of yield and nutritional quality in waxy maize. This work provides a physiological basis and a practical agronomic strategy for the targeted biofortification and yield improvement of maize.