Effect of foliar spray of growth regulators on growth and yield of onion (Allium cepa L.)

A field experiment was conducted during rabi season of 2024-25 at seed production block, new area, University of Agricultural Sciences, Raichur, to study the effect of foliar spray of growth regulators on growth and yield of onion. The experiment was laid out in a randomized block design comprising of nine treatments (T₁) Control, (T₂) GA₃, (T₃) NAA, (T₄) Thiourea, (T₅) Mepiquate chloride, (T₆) Humic acid, (T₇) Ethrel, (T₈) Amino Acid, (T₉) Vermiwash with three replications and were applied as foliar sprays at 30 and 45 days after planting (DAP). The results revealed that application of humic acid @ 100 ppm recorded significantly higher growth and seed yield parameters viz., Plant height (70.32 cm at 75 DAP), Number of leaves per culm (44.13 at 75 DAP), Less days for flower initiation(37.68), Less days to 50 per cent flowering (57.78%), Less days to maturity (115.12), Number of umbels per plant (5), Umbel diameter (5.80 cm), Number of seeds per umbel (228.19), Test weight (4.34 g), Seed yield per umbel (1.91 g), Seed yield per plant (7.73 g), Seed yield per plot (0.23 kg), Seed yield per hectare (469.20 kg), Seed filling per cent (88.07%). Whereas, control recorded lowest values (58.45 cm, 36.11, 44.32, 66.40 days, 134.54 days, 3.10, 3.53 cm, 197.61, 3.61 g, 1.48 g, 5.22 g, 0.17 kg, 330.87 kg and 67.33% respectively). Humic acid, a natural biostimulant, enhances physiological and biochemical functions in plants, promoting better seed development and maturation. Its application improves germination, vigour and viability, thereby ensuring superior growth and seed yield productivity.