The Influence of NAA, GA3 and Calcium Nitrate on Growth, Yield and Fruit Quality of "Le Conte" Pear Trees

Abstract

Aims: Investigate the effect of gibberellic acid, naphthalene acetic acid and calcium nitrate on vegetative growth parameters, fruit set, yield, fruit quality and leaf mineral content of "Le Conte" pear trees. Study Design: Thirty five uniform trees were selected for the present study. The treatments were applied and arranged in a randomized complete block design. Each treatment included five replicates with one tree for each replicate. Place and Duration of Study: This experiment was carried out during two successive seasons, 2012 and 2013, on 8 years old "Le Conte" pear budded on Pyrus communis L. rootstock. The trees were grown in sandy loam soil in a private orchard located at Burg EL-Arab, Alexandria governorate, Egypt. Methodology: The trees were sprayed with water only (control treatment), naphthalene acetic acid (NAA) at 50 and 100 mg/l, gibberellic acid (GA3) at 50 and 100 mg/l and calcium nitrate at 0.5 and 1 mg/l, three times: in full bloom, which was at the beginning of March, a month later and then two months from the first spray. Results: The obtained results showed that the foliar application of NAA, GA3 and calcium nitrate significantly improved shoot length and thickness, leaf area, fruit set and fruit yield. Additionally, they gave a remarkable increase in weight, size and firmness of fruits and N, P, Ca and Mg content in the leaves over control. Among all the used treatments, calcium nitrate at 1 mg/l had the highest beneficial effect. It caused the best remarkable increase in fruit set percentages, yield (approximately 16 kg/tree), yield (ton/hectare), fruit firmness, acidity and vitamin C content. Moreover, it significantly decreased fruit drop percentage, as compared to the control and the other treatments in both seasons. Conclusion: The foliar application of calcium nitrate at 1% had the highest beneficial effect to increase fruit set percentages, yield, fruit firmness, acidity and vitamin C content in the fruit and to decrease fruit drop percentages of "Le Conte" pear trees compared with the control and the other treatments.