EFFECTS OF MECHANICALLY RESTRICTING ENLARGEMENT OF CUCUMBER FRUITS ONWATER AND DRY-MATTER ACCUMULATION

The control of soluble sugar concentration during a rapidly growing st age was investigated in relation to water content in cucumber fruits. To evaluate the influences of the rate of water accumulation on the co ncentration of soluble sugars, the enlargement of the fruits was restr icted by enclosing the fruits within acrylic sleeves to prevent mechan ically the further accumulation of water for 3 to 4 days. The treatmen t restricted fruit enlargement by 40% to 72% of control fruits on a fr esh weight basis, whereas dry matter and hexose contents increased fro m 127% to 138% and from 134% to 173%, respectively. Although sucrose c onstitutes a small percentage of total sugars, it increased significan tly during the treatment. The activity of acid invertase was negativel y correlated to the concentration of sucrose, suggesting that the sign ificant accumulation of sucrose was related to the reduced activity of acid invertase. Whereas the concentration of soluble sugars consisten tly increased with time, the concentration of dry matter remained cons tant during the treatment, indicating that the accumulation of soluble sugars was not due to excessive import of carbohydrates relative to w ater inflow. The relationship between the concentration of soluble sug ars and the rate of water accumulation is discussed.