Calcium and boron interactions affecting fruit quality and yield of apple under temperate conditions

Abstract:

An observation common among apple growers in the Marathwada highlands is that fruit firmness and shelf life have declined over the past decade despite no change in variety or rootstock. Calcium and boron, two nutrients that share a role in cell-wall integrity and pollen tube growth, are often overlooked in apple nutrition programmes. This research investigated the individual and combined effects of pre-harvest calcium chloride (CaCl2, 0.5% w/v) and borax (0.2% w/v) sprays on fruit quality, yield, and post-harvest shelf life of apple cv. Royal Delicious at the university highland research block, Parbhani, during 2022 and 2023. Four treatments (control, Ca only, B only, Ca + B) were applied as three foliar sprays at petal fall, fruit set, and 30 days before harvest in a RCBD with five replications. The combined Ca + B treatment raised TSS to 15.8 deg Brix (control: 12.5), fruit firmness to 7.8 kg/cm2 (control: 6.1), and shifted 38.7% of fruit into the premium grade (>70 mm) compared with 18.3% in the control. Yield increased by 19.4% and shelf life extended by 8 days. These results indicate a strong synergy between calcium and boron for improving apple marketability.