Effect of Putrescine, Gibberellic Acid and Calcium on Quality Characteristics and Maturity Delay of "desert Red" Peach Fruit Cultivar. A: Developmental Aspects and Physical Properties of the Fruit

Prolonging the marketing period of peach fruits in Egypt through introducing new cultivars, breaking dormancy early or delaying maturity of some cultivars by safe compounds would increase the growers' profits. This study was conducted during two successive seasons 2005 and 2006 by using "Desert Red" peach cultivar (Prunus persica L.) grafted on Nemaguard rootstock. Trees were grown at El-Noubarya province, Behera, Egypt. were sprayed with a hand sprayer to the run off. At the initiation of phase ΙΙΙ of the double sigmoid curve the treatments included putrescine at 5 and 10 mM, GA3 at 200 and 400 ppm, in addition to each of the above treatments plus calcium chloride (at 2%, w/v), CaCl2 alone, and the control (water spray). The surfactant tween-80 was added to all treatments at 0.05% (v/v).All putrescine and GA3 treatments whether alone or in the presence of calcium, in addition to CaCl2 alone resulted in retarding the loss of tissue firmness as compared with the control in both seasons. Fruit size, weight, length, and flesh weight were significantly increased by GA3 at 200 and 400 ppm as compared with the control in both seasons. Furthermore, CaCl2 did not significantly affect fruit size, fruit weight, fruit diameter and flesh weight in both seasons. Putrescine treatments, in the presence or absence of CaCl2, were not affective on altering fruit length and diameter in J.Agric.&Env.Sci.Alex.Univ.,Egypt Vol.6 (1)2007 2 both seasons. The incorporation of calcium with either putrescine or GA3 did not consistently result in an added advantage on fruit weight and length. Meanwhile, GA3treated fruit, at 200 or 400 ppm, had a significant increase in flesh weight as compared with the control. Moreover, CaCl2 alone did not significantly alter flesh weight in both seasons. It could be recommended to use preharvest spray with either GA3 at 200 ppm, Putrescine at 5 ppm (441 ppm) to delay maturity of "Desert Red" peach fruits by at least on week without adversely affecting the firmness.