Purpose. To evaluate the effect of pre-sowing soaking of seeds on the plant performance and economic efficiency of watermelon and melon growing on drip irrigation in the South of Ukraine. Methods. Field, measuring, computational, comparative, and mathematical/statistical methods, analysis of economic efficiency. Results. Pre-sowing soaking of seeds in solutions of silicon-containing fertilizers was shown to help obtain early and full-bodied watermelon and melon seedlings, increase the length and number of lateral shoots, and improve fruit setting. Balanced plant nutrition contributed to high performance of watermelon and melon plants in the South of Ukraine. The highest yields of watermelon (23.4 t /ha) and melon (17.5 t/ha) fruits were harvested with 10% Quantum AquaSil solution, which increased the yield by 35.3 and 35.7%, respectively, compared to the untreated control. Silicon-containing fertilizers, 15% Bai-Si and Kelik PotassiumSilicon solutions, increased the fruit yield in watermelon fields by 22.5% and 19.7%, respectively, compared to the untreated control. The greatest economic effect of watermelon and melon growing was achieved by soaking seeds in 10% Quantum AquaSil solution prior to sowing; the profitability amounted to 122 and 101%, respectively. Conclusions. Pre-sowing soaking of seeds in silicon-containing fertilizer solutions contributed to high performance of plants and allowed increasing the economic efficiency of cultivation. The maximum percentage of fruit setting was recorded after seed treatment with 10% Quantum AquaSil solution. For example, this parameter was 67% in watermelon ‘Charivnyk’ and 87% in ‘Didona’ melon. In the south of Ukraine, the economic effect of outdoor watermelon and melon cultivation increased by 16,030–19,220 UAH/ha and 21,230–26,340 UAH/ha, respectively.

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