Effect of plant growth regulators on growth and yield attributes of tomato (Solanum lycopersicum L.)

A grow-bag trial was conducted during the 2024-25 Kharif season at the Government Nursery, Mohgaon, Saja, Bemetara (Chhattisgarh), under the College of Horticulture and Research Station (CHRS), Saja, to evaluate the effect of foliar-applied gibberellic acid (GA₃) and naphthalene acetic acid (NAA) on tomato cv. Kashi Aman. Seven treatments (GA₃ at 75, 80, and 85 ppm; NAA at 90, 100, and 110 ppm; and an untreated control) were laid out in a completely randomized design with three replications and five 12 × 12 in. grow bags per replication. Sprays were applied at 20, 40, and 60 days after transplanting (DAT). Vegetative growth parameters (plant height, stem diameter, and number of branches) were recorded at 30, 45, 60, and 90 DAT, while reproductive responses (days to first flowering, fruits per cluster, fruits per plant, fruit-set percentage, average fruit weight, fruit diameter, and total yield per plant) were assessed at harvest. Foliar GA₃ at 85 ppm consistently produced the most vigorous plants (86.1 cm height, 11.7 mm stem diameter, 11.8 branches) and the earliest flowering (24.2 days). It also maximized yield components: 4.1 fruits per cluster, 20.1 fruits per plant, 83.1% fruit set, 68.2 g average fruit weight, 5.8 cm fruit diameter, and 1.40 kg yield per plant. GA₃ at 80 ppm and NAA at 110 ppm also significantly outperformed the control. These results demonstrate that foliar application of GA₃ at 85 ppm at critical growth stages markedly enhances vegetative vigor, reproductive success, and fruit yield of tomato. Future research should refine hormone dosages, application timing, and validate performance across field conditions and diverse cultivars.