Improving Yield, Fruit Quality and Storability of ‘Zaghloul’ Date Palm Cultivar by Pre-Harvest Sprays of Some Growth Regulators and Bunch Bagging

Abstract

HE PRESENT study was conducted during the two consecutive …….seasons, 2013 and 2014 on fifteen years old "Zaghloul" date palm trees (Phoenix dactylifera L.) grown in a calcareous soil under flood irrigation system to study the effect of pre-harvest spray of the growth regulators gibberellic acid (GA 3 ) at 150 mg/l , naphthalene acetic acid (NAA) at 100 mg/l and ethrel at 1000 mg/l and bunch bagging treatments (about 4 weeks from pollination) on bunch weight, fruit physical characteristics, total soluble solids (TSS), acidity and tannins % at harvest and Rutab, weight loss, ascorbic acid, total phenol content and peroxidase activity during cold storage (0 ± 1) °C and 90-95% RH for 15 days. At harvest, all growth regulators increased bunch weight, fruit weight, fruit length and fruit diameter compared to the control except ethrel which had no influence on fruit weight as compared with the control. NAA spray gave the highest bunch weight than the other treatments. A significant increase was obtained in bunch weight and fruit physical characteristics by bunch bagging compared to un-bagged treatment. TSS % and acidity, as well as tannins, were increased by GA 3 and NAA compared with the control. Ethrel spray resulted in higher TSS content and lower acidity and tannins contents compared with control and other growth regulators. Bunch bagging decreased TSS and tannins while it had insignificant effect on acidity. During cold storage, a significant decrease in Rutab% and fruit weight loss was obtained in both seasons by all sprayed growth regulators except ethrel in the first season. Only ascorbic acid, total phenol content and peroxidase activity was significantly higher with GA 3 and NAA treatment compared with ethrel and control. In this respect, ethrel showed the lowest ascorbic acid, total phenol content and peroxidase activity among other growth regulators. The result of both seasons generally indicated that bunch bagging treatment tended to increase Rutab%, ascorbic acid and reduce peroxidase activity while it had no significant effect on weight loss and total phenol content.