Cherry Tomato Fruit Quality under Limited Potassium Conditions in a Hydroponic System

Potassium is a critical factor for plant growth, particularly in tomato cultivation, where high K levels are essential for achieving high yields and enhancing fruit quality. This study aimed to investigate the effects of varying potassium nitrate (KNO₃) concentrations on two cherry tomato varieties, ‘Tabtim Deang T2021’ (red) and ‘Sweet Boy 1’ (yellow), grown under hydroponic conditions. The plants were subjected to KNO₃ concentrations of 3.0, 1.5, 0.75, 0.50, and 0.37 mM. The findings revealed that a KNO₃ concentration of 1.5 mM was sufficient to support normal plant growth and maintain optimal fruit quality, including pH, total soluble solids, citric acid, and ascorbic acid content, in both cherry tomato varieties. Additionally, the reduction in KNO₃ concentration did not significantly impact the antioxidant activities of the tomato fruits, as measured by 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and ferric ion reducing antioxidant power (FRAP) assays. Furthermore, low K fertilization resulted in minimal changes to the physical, chemical, and biological characteristics of the cherry tomatoes. The study concludes that decreasing K concentration in the nutrient solutions has a limited effect on the overall quality of cherry tomatoes.