Effect of Plant Growth Regulators and Organic Manures on Quality Growth, Yield and Quality of Onion (Allium cepa L.)

A field experiment was conducted during the Rabi season of 2024–25 at the Research Farm of Mewar University, Gangrar, Chittorgarh (Rajasthan), to assess the effect of various plant growth regulators (PGRs) and organic manures on the growth, yield, and quality of onion (Allium cepa L.), variety ‘Agrifound Light Red’. The experiment followed a factorial randomized block design with 16 treatment combinations involving four PGRs (Control, GA₃ @ 100 ppm, NAA @ 100 ppm, and CCC @ 100 ppm) and four organic manure types (Control, FYM @ 12 t/ha, Vermicompost @ 4.0 t/ha, and Poultry manure @ 2.5 t/ha), replicated thrice. The results indicated that the combination treatment P2-GA₃ @ 100 ppm + O4-Poultry manure @ 2.5 t/ha significantly outperformed other treatments in enhancing plant growth parameters such as plant height (up to 48.72 cm), number of leaves (7.16 per plant), and earliness in flowering (minimum 95.17 days to 50% flowering). Yield attributes including polar and equatorial bulb diameter (5.84 cm and 7.08 cm, respectively), neck thickness (1.62 cm), bulb weight (64.07 g), and yield (26.54 t/ha) were also highest under this treatment. Additionally, the same combination produced the best quality in terms of TSS (14.34 °Brix) and sulfur content (0.65%). These findings highlight the synergistic effects of gibberellic acid and poultry manure in promoting onion productivity and quality. The integration of organic manures with plant bioregulators can improve soil health and optimize physiological responses, making it a promising strategy for sustainable onion production under semi-arid conditions.