Effects of Nighttime Heating on Cell Size, Acid Invertase Activity, Sucrose Phosphate Synthase Activity, and Sugar Content of Melon Fruit

Abstract

To determine the relationship among cell size, acid invertase (AI) activity, sucrose phosphate synthase (SPS) activity, and sucrose accumulation in melon (Cucumis melo L.) during early development [from 6 to 16 days after anthesis (DAA)], fruit were heated at night to a minimum of 20 °C. Cells of heated fruit were larger than those of control fruit at 16 DAA but smaller at 50 DAA. AI activity was lower and SPS activity was higher in heated than in control fruit up to 26 DAA. Sucrose, glucose, and fructose contents at 26 and 50 DAA were higher in heated than in control fruit. Heating caused cells to reach mature size earlier than those of control fruit, and maturity was accompanied by earlier decline in AI activity and an earlier increase in SPS activity that promoted soluble sugar accumulation.