Different potassium fertilization levels influence water-use efficiency, yield, and fruit quality attributes of cocktail tomato-A comparative study of deficient-to-excessive supply

Tomato is the foremost vegetable in the world in terms of production and consumption and has considerable nutritional benefits in addition to its economic importance. High yield, water-use-efficiency (WUE), and desirable fruit quality are strongly influenced by potassium (K). So far, the effect of excessive supply of K on those parameters has not been studied in cocktail cultivars. Thus, and for a comprehensive view, we evaluated the effect of six different K fertilization regimes; from deficient K1, moderate K2, optimal K3 and K4, to excessive K5 and K6 on two cocktail tomato cultivars. With increasing K supply, the fruit's content of K, Magnesium (Mg), and Iron (Fe) increased while that of Calcium (Ca), Sodium (Na), and Zink (Zn) decreased. WUE, marketable yield, and total soluble solids (TSS) increased until K4, color and dry matter (DM) until K3, while Titratable acid (TA) reached its highest value at K5 in cultivar (cv.) Primavera. In cv. Yellow Submarine, marketable yield, color, TSS, and TA were the highest at K4, while WUE and DM increased following the highest K supply at K6. Optimal K application-3.66 - 4.00 g plant(-1)-enhanced WUE, marketable yield, and fruit quality attributes such as color attributes a* and b*, TSS, TA, DM of cocktail tomatoes, whereas excessive K fertilization increased the surplus of K and the studied attributes remained unaffected. The results of this study, therefore, indicate that K fertilization should be implemented at the lowest possible efficient concentrations.