여름철 고온이 온주밀감의 당함량에 미치는 영향

Abstract

In order to evaluate the effect of high temperature during summer on the concentration of sugars in fruit juice of early-maturing satsuma mandarin, potted plants of two cultivars of 'Miyagwa' and 'Okitsu'were grown in four rooms of phytotron (two pots of each cultivar per room) from April 1 to harvest. For the period from July 11 until Sept. 10, two rooms were kept at 25℃ of daily mean air temperature with diurnal range of 6℃, while the remaining two rooms at 30℃. During the remaining period before and after treatment, all rooms were kept under the identical temperature regime of the same daily mean air temperature with diurnal range of 6℃ as that in outdoors. More increase in fruit diameters (both longitudinal and transversal) was observed in the room of 25℃ during the treatment, and more increase in the room of 30℃ after the treatment, resulting in the same size in November. Concentration of both fructose and glucose in the fruit juice was slightly higher in the room of 25℃ on September 11, and the difference became larger during maturation. Concentration of sucrose was slightly higher in the room of 30℃ on September 11, but more increase in the room of 25℃ during maturation resulted in significantly higher sucrose concentration in the room by 25 mg·L-1 comparing to the room of 30℃. Increase in the activity of sucrose synthase (SS) showed the same tendency as that of sucrose. Positive correlation between the activity of SS and the concentration of sugars, especially sucrose, was recognized. Changes in the activity of sucrose phosphate synthase were not consistent between cultivars. Decrease in acidity of fruit juice during maturation was not affected by the treatments. Peel coloration was delayed in the room of 30℃.