The Effect of the Foliar Application of Potassium, Calcium, Boron and Humic Acid on Vegetative Growth, Fruit Set, Leaf Mineral, Yield and Fruit Quality of 'Anna' Apple Trees

摘要

This experiment was carried out during 2012 and 2013 seasons on seven years old "Anna" apple trees ( Malus domestica L.). Trees were planted at 5Χ5 meters on sandy loam soil under drip irrigation system in a private orchard at El-Nubaria, Behera Governorate, Egypt. The experiment involved ten foliage spraying treatments as follows: control, sprayed with water, K at 2% as potassium sulphate, Ca at 0.2% as calcium chloride, B at 0.2% as boric acid, H.A. at 5% as humic acid, potassium sulphate+ humic acid, calcium chloride+ humic acid, boric acid+ humic acid, potassium sulphate+ calcium chloride+ boric acid and potassium sulphate+ calcium chloride+ boric acid+ humic acid. The obtained results showed that potassium sulphate+ calcium chloride+ boric acid+ humic acid combination was the best treatment. This combination had the highest positive effect to improve the percentages of yield, fruit set, reducing sugar and total soluble solids. Also, it increased Ca, P, K, N, B, Zn, Mn and Fe in the leaves in the two seasons, as compared to the control. Moreover, this combination improved significantly anthocyanin concentration, TSS/acid ratio, shoot diameter, shoot length, leaf area, fruit diameter, fruit length, average fruit weight and fruit firmness. It decreased the percentages of fruit drop and acidity in the two seasons as compared to the control and the other treatments.