IMPACT OF BORIC ACID SPRAYING DATE WITH DIFFERENT CONCENTRATIONS ON YIELD AND FRUIT QUALITY OF Pyrus communis cv. 'LE-CONTE' PEAR TREES

The aim of the study was to examine the response of pear (Pyrus communis, L.) trees to foliar applications of boric acid. The experiment was carried out during 2010-2011 and 2011-2012 seasons in a commercial orchard in El-Khatatba city, Monifia Governorate, Egypt on mature ‘Le-Conte’ pear trees grafted on Pyrus communis seedlings planted at a space of 5×5 m on a sandy soil under drip irrigation system and modified central leader trained. Annually, foliar sprays with boric acid were applied (i) at 1st September after harvest or (ii) at white bud stage before bloom. Spray treatments involved application of boric acid at a rate of 50, 100 or 150 ppm. Trees untreated with boric acid served as the control. The results revealed that foliar applications of boric acid after harvest or before full bloom at white bud stage increased boron concentration in flowers, fruit set percentage and fruit yield. Additionally, these applications resulted in higher mean fruit weight, size, length, diameter, firmness, seed number per fruit, soluble solids concentration and titratable acidity than those from the control trees. These findings indicate that pre-bloom and postharvest boric acid sprays are successful in increasing pear tree yielding and in improving fruit set. But, boric acid application at the rate of 150 ppm at 1st September after harvest was superior in this respect.