Journal of Advances in Biology & Biotechnology

A field experiment was conducted during 2023-2024 at the Orchard, Department of Horticulture, Faculty of Agriculture, Annamalai University, Annamalai Nagar, Chidambaram, Tamil Nadu, to evaluate the synergistic effects of plant growth regulators and micronutrients on the growth, flowering, yield and fruit quality of watermelon (Citrullus lanatus) cv. Arka Shyama. The experiment comprised fourteen treatments laid out in a Randomised Block Design with three replications. The treatments included the recommended dose of fertilisers with farmyard manure, either alone or in combination with foliar application of Ethrel, Brassinosteroid and a micronutrient mixture at different concentrations. The results showed significant variation among treatments for all recorded growth, flowering, yield and quality parameters. Among the treatments, T₁₃, comprising FYM 20 t ha^-1 + RDF + Brassinosteroid at 2 ppm + micronutrient mixture at 2% foliar spray, recorded the highest vine length, number of branches, number of leaves and number of nodes per vine. The same treatment also resulted in earlier male and female flower appearance, a higher number of female flowers and a more favourable sex ratio. Yield attributes were also superior under T₁₃, with 3.12 fruits per plant, an average fruit weight of 3.68 kg, yield per plant of 11.48 kg and yield of 57.40 t ha^-1. Quality parameters, including fruit length, fruit girth, total soluble solids, total sugars, reducing sugars, non-reducing sugars and ascorbic acid content, were also highest under T₁₃. The findings indicate that the combined foliar application of Brassinosteroid at 2 ppm and micronutrient mixture at 2%, along with FYM and RDF, improved the growth, flowering, yield and fruit quality of watermelon under the conditions of the present study.