An investigation was carried out for two consecutive years to study the suitability of 1-naphthaleneacetic acid (NAA) alone or in combination with calcium chloride (CaCl2) to control preharvest fruit drop and their effect on fruit quality of ‘Red Delicious’ apple (Malus pumila Mill.). The following five treatments combinations were tested: (1) control, the trees sprayed with water only; (2) a single spray with NAA; (3) two sprays with NAA at an interval of 14 d; (4) a single spray with NAA CaCl2; and (5) two sprays with NAA CaCl2 in combination at an interval of 14 d. NAA was sprayed at the rate of 20 mg L-1 and CaCl2 was sprayed at 3 g L-1. NAA applications reduced fruit drop appreciably when sprayed one month before harvest. The spray was effective in retaining the fruit on the tree for ∼14 d and the second spray after the 14 d of the first spray retained the fruit for another ∼14 d; however, the keeping quality of the fruit was reduced. No significant effect of CaCl2 sprays could be observed on maintaining the keeping quality of apple.
chlorure de calcium