Journal of Advances in Biology & Biotechnology

Ethephon (2-chloroethylphosphonic acid) is a widely used ethylene-releasing compound that exerts significant effects on the vegetative and reproductive development of cucurbit crops. Upon foliar application, ethephon decomposes in plant tissues to release ethylene, which inhibits cell elongation in the shoot meristem, promotes lateral branching, and advances the onset of female flowering. A field experiment was conducted at the experimental field of the Department of Agriculture, Khalsa College, Amritsar, India, during the Rabi season of 2018–2019 to investigate the effect of foliar application of ethephon and maleic hydrazide at varying concentrations (50, 100, 150 and 200 mg L⁻¹) on the vegetative growth characteristics of zucchini (Cucurbita pepo L.) cv. Dark Green. The experiment was laid out in a Randomized Complete Block Design (RCBD) with nine treatments and three replications. Growth parameters recorded included plant height, number of leaves per plant, number of nodes per plant, and days to first harvest. Results demonstrated that ethephon at 200 mg L⁻¹ significantly reduced plant height (49.25 cm at 60 days after transplanting, DAT) whilst simultaneously producing the maximum number of leaves (61.16) and nodes (47.36) per plant. The same treatment recorded the minimum days to first harvest (38.39). Maleic hydrazide treatments reduced plant height at all concentrations, with moderate effects on leaf and node development. The untreated control consistently recorded the tallest plants, the fewest leaves and node. These findings indicate that ethephon at 200 mg L⁻¹ is the most effective treatment for promoting compact plant architecture in zucchini under sub-tropical Indian conditions.