Effect of potassium fertilization on the yield and quality of two tomato varieties

Lycopene is the main antioxidants in fresh tomatoes which important in the prevention of cancer. The antioxidants components of tomatoes can be influenced by management practices during period of tomato production, including variety and nutrition. In this study, the effects of potassium fertilizer on yield and quality of two varieties of tomatoes were investigated. Two local varieties of tomato (Karina and Mawar) were planted in polybags using different level of potassium fertilizer (50, 100, 150, 200, 250 kg.ha-1 K2O). The results showed that the effect of potassium fertilizer appear on Karina variety, particularly on fresh weight of fruit at 100, 150 and 250 kg.ha-1 of K2O. In addition, the tomato fruit of Karina variety contained the higher fruit diameter, fresh weight per fruit and larger amounts of beta-carotene. While the tomato fruit of Mawar variety had the higher amounts of lycopene and Vitamin C. These results indicated that carotenoid biosynthesis in tomatoes were more affected by variety than potassium fertilization did.