Influence of Citrus aurantium L. and Poncirus trifoliata (L.) Raf. Rootstocks and Nutrient Sprays on Granulation of Valencia Sweet Orange [C. sinensis (L.) Osbeck] Fruits

摘要

Experiments on the influence of rootstocks and foliar splays of macro-and microelements on granulation and quality of Valencia sweet orange (Citrur sinensis (L.) Osbeck) fruits were cairied out over a three-year-period (1996—1998) at the Agios Saranda Pomology Research Station. The Poncirus trifoliata rootstock markedly reduced granulation with 31 % compared with 73 % on C. aurantium rootstock. The combined spraying with zinc, + manganese and copper (each 0, 5 %) was the best treatment in reducing granulation and enhancing fruit quality. This combination reduced granulation on both rootstocks to about 12-41 % compared to that of control treatment. Zinc or copper separately reduced the incidence of granulation to almost 24 %— 28 % compared to the unsprayed control treatment on both rootstocks. Potassium nitrate (1 %), calcium hydroxide (2 %) and boric acid (100 mg l~(-1)) reduced granulation to a lesser extent. Most of these treatments improved fruit quality and resulted in much more endocarp juice, total soluble solids, and vitamin C content than the control and also markedly reduced peel weight and acidity. The use of specific lootstocks and foliar application of nutrients is a powerful tool in reducing granulation and in improving fruit quality in sweet Valencia orange.