Influence of Naphthaleneacetic Acid and Gibberellic Acid on Growth, Flowering, and Yield Performance of Okra (Abelmoschus esculentus) at Katahari, Morang, Nepal

Okra (Abelmoschus esculentus L. Moench) is an economically significant vegetable crop whose yield potential in Nepal remains below achievable levels owing to limited adoption of yield-enhancing technologies, including plant growth regulators. This study evaluated the individual and combined effects of naphthaleneacetic acid (NAA) and gibberellic acid (GA₃) on vegetative growth, flowering, and pod yield of okra at Katahari, Morang, Nepal. A randomised complete block design experiment comprising seven treatments and three replications was conducted from March to June 2025. Treatments included a water control (T1), GA₃ at 100 and 150 ppm (T2 and T3), NAA at 100 and 150 ppm (T4 and T5), and combinations of GA₃ and NAA at 100 and 150 ppm (T6 and T7). Plant growth regulators were applied as foliar sprays at 25 and 40 days after sowing. Vegetative, flowering, fruit, and yield parameters were recorded and analysed using analysis of variance with least significant difference test at p ≤ 0.05. NAA at 150 ppm produced the maximum leaf area (3,700 cm²), stem diameter (2.77 cm), total flowers (72 plant⁻¹), fruits (25.33 plant⁻¹), and pod yield (14.37 t ha⁻¹), representing a 39.92% increase over the control. GA₃ at 150 ppm induced the tallest plants (96.00 cm), while GA₃ at 100 ppm produced the longest pods (15.89 cm). Combined GA₃–NAA treatments reduced pod yield relative to the better-performing single-hormone treatments, which may indicate possible antagonistic interactions, despite accelerating flowering by up to 14 days compared with the control. Foliar application of NAA at 150 ppm is recommended for maximising okra yield under Terai agro-ecological conditions, while GA₃ at 100 ppm is suitable for early-harvest niche markets. Combined applications at the tested concentrations are not recommended.