Optimizing grape growth, berry quality and phenolic compounds with foliar co-application of iron and calcium.

• Ca & Fe co-application enhances photosynthesis, growth and berry quality. • Ca & Fe co-application increases berry size, weight and yield. • Balanced Ca & Fe supply enhances sugars, amino acids and flavonoids in grapes. • Ca & Fe co-application offers holistic approach to optimize vineyard management. Iron (Fe) and calcium (Ca) are pivotal elements influencing grape growth and wine quality. However, the combined effects of these fertilizers on grape physiology and berry quality remain elusive. Herein, we established four treatments: no fertilization (CK), foliar Ca fertilization (Ca1Fe0), foliar Fe fertilization (Ca0Fe1), and foliar co-application of Ca and Fe (Ca1Fe1), to unravel their impacts. Ca1Fe1 remarkably enhanced grape leaf photosynthesis, elevated chlorophyll content, and augmented amino acids, flavanols, flavonols, and anthocyanins in berries, culminating in a yield increase of 8.36 %. Correlation analysis revealed that Ca1Fe1 bolstered crop light-use efficiency and secondary metabolism, amplifying berry quality and yield. Principal component analysis underscored the profound synergism of iron and calcium co-application, profoundly enhancing fruit quality and yield. These findings offer vital theoretical underpinnings for future fertilizer strategies aiming to enhance berry and wine quality and nutritional value. [ABSTRACT FROM AUTHOR]