IMPACT OF SUSTAINED DEFFICIT IRRIGATION AND FOLIAR SPRAY OF ASCORBIC ACID ON PRODUCTIVITY AND PEEL DISORDERS OF WONDERFUL POMEGRANATE TREES

Abstract

The investigation was carried out during 2017and 2018 seasons on Wonderful pomegranate trees grown at private orchard located on Cairo-Alexandria Desert road about 50 Km from Cairo, Egypt. Trees planted at 3x5 meters apart in sandy soil and watered from wells using drip irrigation system. The trial was a factorial experiment, hence sustained deficit irrigation100%, 80% and 60% from crop evapotranspiration (ETc) throughout season, the occupied main plot, whereas foliar sprays of ascorbic acid treatments at 0, 500, 750 and 1000 ppm /tree located in the subplots were carried out two times, the first foliar spray was done at full bloom and the second one was performed four weeks later. The results showed that leaf characteristics (leaf area and total chlorophyll), number of fruits per tree, yield and fruit quality traits (weigh, length, diameter, weight of fruit grains, flesh percentage, weight of 100 grains and juice volume) recorded the highest values with higher both irrigation level and sprays of ascorbic acid treatments. On the contrary fruits cracked percentage and fruits sunburned percentage, peel thickness, total sugar, TSS, TSS/acidity, ascorbic acid and water used efficiency showed an adverse correlation with irrigation level. Also, spraying by ascorbic acid is reducing number of fruit cracked, number of sunburned fruits and acidity. On other hand, peel thickness, total sugar, TSS, TSS/acidity and ascorbic acid concentration were increasing. Therefore, sustained deficit irrigation is considered to be an effective strategy for arid and semi-arid regions, moreover ascorbic acid may be used to prevent or mitigate oxidative damage caused by sustained deficit irrigation.