Effect of zinc and boron application on fruit set, quality and yield of apple cv. Red Delicious

An experiment was carried out during 2014–15 on twenty years old "Red Delicious" apple trees, to study the effect of zinc sulphate and boric acid on fruit set, quality and yield. Treatments including 20 g of boric acid were applied per tree as a basal dose one month before the bud break stage, zinc sulphate (0.1%) and boric acid (0.2%) were applied as foliar spray at pink bud stage. The results revealed that application of 20g boric acid (basal) in combination with zinc sulphate (0.1%) and boric acid (0.2%) as foliar spray significantly increased the fruit set (41.62%), fruit length (4.50 cm), fruit diameter (5.71 cm), fruit volume (20.88 cm³), TSS (12.90 ^°Brix), total sugar (7.76%), ascorbic acid (4.00 mg/100g), pollen germination (69.08%), yield (72.89 kg/tree) and expressed minimum fruit drop (48.78%) and titratable acidity (0.30%) in comparison to other treatments. From current investigation, it was concluded that the application of zinc sulphate and boric acid as foliar spray in combination with basal dose of boric acid gave beneficial response as compared to single application under high hills of Uttarakhand.