Preharvest Foliar Applications of Citric Acid, Gibberellic Acid and Humic Acid Improve Growth and Fruit Quality of 'Le Conte' Pear (Pyrus communis L.)

A two-year (2020-21) study was conducted to investigate the possibility of relying of ten-years old pear trees grown on sandy loam soil irrigated by drip on citric acid (CA), gibberellic acid (GA(3)) and humic acid (HA). The CA was applied at the concentrations of 500, 1000 and 1500 ppm, GA(3) at 50, 100 and 150 ppm and HA at 3, 4 and 5%, whereas water spray was used as the control. The results of our study proved that CA, GA(3) and HA improved the shoot length, shoot thickness, leaf area and leaf chlorophyll of pear as compared with the control. Moreover, they also positively increased the fruit set percentage and final yield of 'Le Conte' pear. The fruit weight, size and firmness were also improved under the influence of aforementioned treatments. The fruit soluble solids, total sugars, leaf nitrogen, leaf phosphorus and leaf potassium of pear were also enhanced as compared with the control. Additionally, spraying of GA(3) at 150 ppm, as well as, HA at 5 and 4% were the superior treatments and showed the most significant impact on plant growth, yield, fruit quality and leaf mineral content of pear. This study provides a basis for the future elucidation of HA-, GA(3)- and CA-modulated molecular mechanisms in pear, which can make a significant contribution in the scientific community.