ウンシュウミカン果実の成熟に伴う呼吸及びエチレン発生量の変化

Abstract

Seasonal changes in growth, chemical composition, peel color, respiration and ethylene production of satsuma mandarin (Citrus unshiu Marcovitch) fruit were investigated in relation to maturation. Two cultivars of satsuma mandarin, ‘Okitsu Wase’, an early maturing cultivar and ‘Silverhill’, a common cultivar, were used in this study.The results obtained were as follows.1. Fruit weight and diameter of ‘Okitsu Wase’ increased gradually until early December and decreased thereafter. The maximum weight and diameter of ‘Silver-hill’ occurred between early and mid-December.2. Fruit of ‘Okitsu Wase’ reached full color in early December while in ‘Silver-hill’ full color was reached in mid- or late December.3. The total sugar content and °Brix of the juice increased markedly until early December in ‘Okitsu Wase’, and until mid-December in ‘Silverhill’.4. A rapid reduction in the acidity of ‘Okitsu Wase’ fruit occurred in mid-October or early November, while the acidity of ‘Silverhill’ fruit declined rapidly until early November.5. The respiration rate of ‘Okitsu Wase’ fruit decreased slightly up to early October, and thereafter increased until January or March of the following year. The respiration rate of ‘Silverhill’ fruit increased slightly until mid-October or early November and continued to increase steadily in the following year.6. The rate of ethylene production decreased until early October in ‘Okitsu Wase’ fruit, and decreased up to mid-or late October in ‘Silverhill’ fruit. Thereafter, the rate of ethylene production in both cultivars remained constant at a low level up to early January of the next year, and then increased.