EFFECTS OF NIGHT-HEATING OF FRUIT ON CELL SIZE REGULATION AND SUCROSE ACCUMULATION IN THE OUTER PORTION OF WATERMELON (CITRULLUS LANATUS MATSUM. ET NAKAI)
To investigate the effects of night temperature on sugar accumulation in water¬melon fruit, fruits were treated with higher night-time temperature in a greenhouse. The minimum night-time ambient temperature of the heating box (18°C) was approximately 6°C higher than that of the control. The weight of heat-treated fruit at the end of heating treatment, 16 days after anthesis (DAA), was greater than that of control, but fruit weight at harvest, 42 DAA, was almost the same in both treatments. Cells of all portions of the heat-treated fruit at 16 DAA were much larger than those of the control, and cells in the outermost rectangular parallelepipeds (RPs; 15-mm long-samples that were serially collected from a 10-mm thick disk along a 10-mm wide strip removed at the maximum transverse diameter of the fruit) of the heat-treated fruit were 80 µm or more larger than those of the control. However, cells from the outer portions of the heat-treated fruit at 42 DAA were smaller than those of the control. At 16 DAA, the number of RPs with sucrose concentration of 2 g L-1 or greater were 6 and 9 in control and heat treated fruit, respectively. At 42 DAA, the sucrose concentration in the outer RPs of the heat-treated fruit was much greater than that in the outer RPs of the control the number of RPs with a sucrose concentration of 40 g L-1 or more was 5 in the control, and 11 in heat-treated fruit. Mean sucrose, glucose and fructose concentration in fruit at 16 DAA did not differ between treated and control fruit. However, at 42 DAA the sucrose concentration of heat-treated fruit was 32% greater than that of the control. Glucose and fructose concentrations were lower in heat-treated fruit than in the control.
Kano, Y., Ikeshita, Y., Kanamori, Y. and Fukuoka, N. (2013). EFFECTS OF NIGHT-HEATING OF FRUIT ON CELL SIZE REGULATION AND SUCROSE ACCUMULATION IN THE OUTER PORTION OF WATERMELON (CITRULLUS LANATUS MATSUM. ET NAKAI). Acta Hortic. 975, 393-402
cell size, Citrullus lanatus Matsum. et Nakai, night-heating of fruit, sugar accumulation, watermelon