Effect of spraying of gibberellic acid (GA3) and foliar fertilizer (Agroleaf) on the seedling growth of plum cultivar ‘Hollywood’

The study was conducted at the Hindia Horticulture Station, Karbala, Iraq-The general company for Horticulture and Forestry, Ministry of Agriculture for the period from March 15 to October 15, 2017. The aim of the investigation was to examine the issue of spraying gibberellic acid and foliar fertilizer (Agroleaf) on the vegetative growth indicators of the plum seedlings of cultivar Hollywood grafted on apricot seedlings. The factorial experiment was conducted using complete randomized design (CRD) with three replications keeping four levels (0, 25, 50 and 75 mg/l) of gibberellic acid and three levels (0, 10 and 20 mg/l) of Agroleaf foliar fertilizer. The effect of spraying with gibberellic acid @ 75 mg/l gave significantly higher values for the length (82.2 cm) of the main stem, 7.43 mm for diameter of the seedling stem, 23.22 cm2 for the leaf area and 40.7 SPADS for chlorophyll. The spraying with gibberellic acid @ 50 mg/l produced significantly higher number of branches (7.17), leaves number (47.37), dry weight of seedlings (42.5 g), leaf N content (1.79%), phosphorus content (0.29%) and potassium content (1.70%) compared with control where no gibberellic acid was sprayed. The treatment of foliar fertilizer @ 20 g/l significantly increased the length of main stem, diameter of seedling stem, number of leaves, leaf area, SPADS for chlorophyll, dry weight of seedlings, number of branches, leaf N content, leaf phosphorus content and leaf potassium content to the tune of 87.13 cm, 7.40 mm, 47.1 leaves, 2523.7 cm2, 42.03 SPADS, 43.65 g, 6.73 branches, 1.87, 0.32 and 1.69%, respectively. The interactions between gibberellic acid and foliar fertilizer (75 mg/l × 20 g/l and 50 mg/l × 20 g/l) produced significantly higher values of these growth traits of plum compared to other interaction treatments.