Effect of Spraying Citric Acid Macro and Micro Nutrients on Yield and Berries Quality of Red Globe Grapevines
This investigation was conducted during the two successive growing seasons of 2016 and 2017 in a private vineyard located at Matay center, Minia Governorate; to evaluate the efficiency of foliar spraying citric acid and some nutrients on vegetative growth aspects, yield and berry quality attributes of Red Globe grapevines. The chosen vines were thirteen-year-old, grown in a sandy soil, spaced at 2 × 3 meters apart and irrigated by the drip irrigation system. The vines were pruned during the third week of January in both seasons of the study so as to maintain a load of 84 buds/vine (7canes × 12 buds/cane) and trellised by the Spanish Parron system. Eight foliar treatments were foliar sprayed as follows:- Tap water (control), citric acid at 1000 ppm, macro-elements (N,P,K,Mg) at 0.5%, micro-elements (Fe,Zn,Mn,B) at 0.1%, citric acid + macro-elements, citric acid + micro-elements, macro-elements + micro-elements and citric acid + macro-elements + micro-elements. The results showed that foliar application of citric acid (1000 pppm), macro-elements (0.5%) and micro-elements (0.1%) either alone or in combination among them had the best results in comparison with control in both seasons. Triple application of citric acid, macro-elements and micro-elements resulted in significantly the highest yield and good components as well as the best physical properties of clusters further improved the physical and chemical characteristics of berries, ensured the best vegetative growth aspects and increased leaf content of nitrogen, phosphorus, potassium and buds content of gibberellic acid and indole acetic acid of Red Globe grapevines.