Effect of potassium applications on plant development, fruit quality and yield in grafted watermelon

In this study, it was aimed to determine the effects of different doses of potassium (K) applications on plant growth, fruit yield and fruit quality in grafted watermelon. Odipus watermelon grafted on TZ 148 rootstock was used as plant materials in the study. The experiment was established in 2019 in Pınarcık, Ankara Province, Beypazarı District, in a complete randomized block design with 3 replications and 10 plants each replication. Four different doses of K (0, 15, 30, 45 kg / da) were applied by fertigation method to the grafted watermelon plants. The effects of K applications on morphological parameters, pomological parameters, leaf nutrient content and yield were determined. With the effect of increasing K doses; significant increases were determined in plant stem diameter, stem length, number of nodes, leaf width, leaf length and leaf area. The highest values in the examined morphological parameters were obtained at 45 kg/da K application. K applications also increased the average fruit weight and total fruit yield, and these increases were statistically significant. 45 kg/da K application increased fruit yield by % 54.72 compared to the control (0 kg/da). With the effect of K applications, fruit quality was also positively affected, especially the fruit total soluble solids value was 7.93% in control plants, while it was determined as 10.46% in 45 kg/da potassium application. K applications generally caused increases in leaf macronutrient contents, and the increase in K and Mg nutrients was statistically significant. The increase in Zn micronutrient was statistically significant. As a result, it is recommended that the K dose of 45 kg / da should be applied in grafted watermelon cultivation due to its positive effect on the examined parameters, especially the morphological parameters and fruit yield.