Thesis (Ph.D.) - Cairo University - Faculty of Agriculture - Department of Agricultural Botany

The present study was carried out during two successive seasons of 2011/2012 and 2012/2013 to study the effect of GA₃ (20 and 30 ppm), some micronutrients, i.e. boric acid (100 and 200 ppm) chelated zinc (62.5 and 125 ppm) and K-silicate (100 and 200 ppm)as well as chitosan (250 and 500 ppm) foliar applications on growth, fruit yield and fruit quality as well as leaves and fruit chemical compositions of 2Washington3 navel orange trees grown at two different location i.e., Elqalubia and Elmonufia governorates, Egypt. After harvest, fruits were stored at 2{u00B0}C and R.H. 85-90% for 45 days. The results indicated that GA₃, K-silicate and chitosan foliar application treatments recorded a significant increase in some vegetative growth, fruit set %, yield as well as fruit physical and chemical characteristics, i.e. weight loss, firmness, color and juice %. In addition, chemical composition of leaves, i.e. total sugars, total free amino acids, total soluble phenols, total pectin and plant hormone as well as chemical composition of fruits, i.e. T.S.S.%, acidity, ascorbic acid, total sugars, total free amino acids, total soluble phenols and mineral nutrients of leaves and fruits, i.e. N, P, K, Ca, B, Zn and Si concentrations. Generally, the results revealed that trees showed a significant increase in all most previous characteristics with treated by GA₃, K-silicate and chitosan foliar applications improved most of the studied in fruit quality and reduced fruit weight loss during cold storage at 2{u00B0}C

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