Watermelon is a widely cultivated cucurbitaceous crop with economic and dietary significance. The plant's ability to reproduce effectively relies on the harmonious growth and maturation of both its male and female flowers. At the farm level, determining the exact amount of ethylene required to regulate the development and sexual expression of individual floral buds remains uncertain, despite the known influence of exogenously applied ethylene on these processes. The goal of the research was to explore how the ethephon doses influence vegetative characteristics, sex expression, and watermelon yield. The experiment, employing a one-factorial Randomized Complete Block Design (RCBD) comprising five treatments and four replications, was conducted in a farmer's field in Buttabari, Jhapa. Using R-stat software, the data were analyzed at a 5% level of significance. Treatment consisted of Ethephon with four doses namely; 100ppm, 200ppm, 300ppm, 400ppm, and a control. Ethephon application was done twice, once at the two true-leaf stages and another at four true-leaf stages. The study revealed that plant height decreased with ethephon compared to the control, reaching a minimum of 280.1 cm at 400 ppm and a maximum of 307.1 cm in the control. Additionally, the highest branch numbers were observed with ethephon at 200 ppm. The plot treated with 200ppm ethephon was found to be more effective than alternative doses at increasing the total number of female flowers, bearing 15.25 female flowers per plant. Control (166.50 per plant) and 400 ppm (150.00 per plant) had the highest and lowest male flower counts per plant, respectively. A maximum yield of 25.12 t/ha and a minimum yield of 19.1 t/ha were determined at 200 ppm and control, respectively. Hence, farmers are found to benefit from ethephon doses of 200 ppm.

This study was carried out at the research field of Rainas Municipality, lamjung, Nepal from February to June 2022. It was conducted to evaluate the effect of different doses of ethephon on vegetative character, sex expression and yield of cucumber. The experiment was laid out in Randomized Complete Block Design (RCBD) with 4 replications and 5 treatments (four different doses of ethephon @ 100 ppm, @ 300 ppm, @ 400 ppm and @ 500 ppm as well as water spraying as control). Spraying was done twice, the 1st at two true leaf stage and the 2nd at four true leaf stage. The observed data were analyzed using Gen stat and Duncan’s Multiple Range Test (DMRT) to find out the significant differences between the mean values at 5% level of significance. Among various concentration of ethephon, the most potent doses of ethephon to increase female flower were 100 ppm, 300 ppm and 400 ppm. The treatment with 300 ppm ethephon result early emergence of female flower, higher number of female flower and lower sex ratio followed by 400 ppm. Yield of cucumber was found higher with 300 ppm ethephon comparison to other treatment. The benefit-cost ratio (B:C ratio) was found highest at 300 ppm ethephon treatment and lowest in the control group. Considering various impacts of different doses of ethephon, treatment with 300 ppm ethephon is recommended.