THE INFLUENCE OF DIFFERENT ROOTSTOCK HYBRIDS ON FRUIT QUALITY OF THE DIPLOID WATERMELON HYBRID YUKON F1 AND THE TRIPLOID WATERMELON HYBRID KIDMAN F1 IN THE CONDITIONS OF THE LEFT BANK FOREST STEPPE OF UKRAINE

Study of the influence of various commercial rootstocks on the quality of diploid and triploid watermelon fruits in the conditions of the Left Bank Forest Steppe of Ukraine. Methods. Laboratory, mathematical and statistical - statistical processing of the results of the experiment. The results. Based on the results of the research conducted in 2019-2021, we see that grafting on bottle gourd rootstocks of the hybrid Pelops F1 and the interspecific hybrid Cobalt F1 is used as an effective option for combating diseases, increasing yield, and resistance to abiotic factors in the production of watermelons; however, this process may affect fruit quality parameters. The aim of this study was to determine the effect of different rootstocks on vitamin C content, total soluble solids, total sugar and nitrate content in Kidman F1 and Yukon F1 watermelon hybrids at harvest. The study determined the influence of two rootstocks on some qualitative characteristics of watermelon fruits. The results showed that the quality parameters of the samples varied depending on the combination of the watermelon hybrid and the rootstock hybrid. Inoculation did not significantly affect vitamin C content and was lower than that of control plants in both diploid and triploid watermelons. The highest content of vitamin C was in Yukon F1 watermelon (in control) - 8.72 mg/100 g, and the combination of Yukon F1 with Cobalt F1 8.65 mg/100 g and Yukon F1 with Pelops F1 8.37 mg/100 g, respectively. Grafted watermelon plants on Cobalt F1 rootstock had the highest total soluble solids content in the test, which was -10.88% on Kidman F1, which was 1.5% more than the control, and 10.21% on Yukon F1, which was 1.06% more than the control, respectively. The highest content of total sugar was observed in the combination of Yukon F1 and Cobalt F1 8.84%, which is 1.71% more than the control, and the combination of Kidman F1 and Pelops F1 8.69%, which is 0.79% more than the control plants respectively. The content of nitrates was below the MPC (60 mg/kg) and ranged from 21.4 to 27.7 mg/kg. The lowest nitrate content was observed on the combination of Cobalt F1 rootstock and Kidman F1 watermelon 21.4 mg/kg, and on Yukon F1 watermelon 23.9 mg/kg, respectively, which is not significantly different from the control plants. Conclusions. The conducted studies indicate the expediency of using different rootstocks for diploid and triploid watermelons to improve fruit quality in the conditions of the Left Bank Forest Steppe of Ukraine. Inoculation provides a significant increase in the content of dry soluble matter, total sugar, and a lower content of nitrates, but inoculation negatively affected the content of vitamin C, especially in triploid watermelon. Comparing the two rootstocks, over three years of testing, we can conclude that grafted watermelon plants on the Cobalt F1 hybrid rootstock had a higher content of dry matter, total sugar, and lower nitrate content than on the Pelops F1 rootstock. The feasibility of using grafted plants in modern growing conditions has been proven.