Effect of Leaf Pruning and Plant Growth Regulators on Growth, Yield and Quality of Summer Squash under Himalayan Valley Conditions

Abstract

A field experiment was conducted during summer 2024 at the Horticultural Research Centre, Hemvati Nandan Bahuguna Garhwal University, Srinagar, Uttarakhand, India, to evaluate the individual and interaction effects of leaf pruning and gibberellic acid (GA₃) on summer squash (Cucurbita pepo L.) cv. Pusa Pasand. The experiment was arranged in a factorial randomised block design with three replications. Three pruning treatments—no pruning, removal of the first and second leaves at 45 days after sowing (DAS), and removal of the third and fourth leaves at 55 DAS—were combined with four GA₃ concentrations: 0, 100, 200 and 400 ppm, producing 12 treatment combinations. Growth observations were recorded at 45 DAS, 60 DAS and harvest, while yield and fruit-quality attributes were assessed at harvest. The combination P₂G₃, comprising removal of the third and fourth leaves at 55 DAS with 400 ppm GA₃, recorded the highest harvest plant height (45.72 cm), plant spread (2,180.97 cm²), stem base diameter (2.05 cm) and number of leaves per plant (25.86). It also produced 22.50 male flowers, 3.23 female flowers, 3.06 fruits per plant, an average fruit weight of 167.63 g, a plot yield of 39.20 kg and a yield of 156.80 q ha⁻¹. Quality responses varied among treatments: maximum total soluble solids, ascorbic acid content and fruit dry weight occurred under P₁G₂, P₂G₁ and P₁G₀, respectively. Thus, P₂G₃ showed the strongest overall response for growth and yield, whereas quality optimisation was trait-specific.