Variation in Sugar Content in Fruit of Four Strawberry Cultivars Grown in the Field and under Forced Culture, Harvest Years, and Maturation Stages

Abstract

The soluble sugar content and composition in four strawberry cultivars grown in the open field and under forcing culture and sampled at various maturation stages in different harvest seasons were compared. 1. Sucrose, fructose, and glucose are the major sugars, and inositol and sorbitol are the minor ones in the sugar compostion of strawberry fruit. Content and composition of souluble sugars differed among cultivars, fructose and glucose being higher in 'Toyonoka' and 'Hokowase' than in 'Nyoho' and 'Reiko' fruits. 2. The percentage of fructose or glucose to total sugar content was large in 'Toyonoka' and 'Hokowase' as compared to 'Reiko' and 'Nyoho' during the early maturation stages; the percentage decreased in 'Reiko' and 'Nyoho', while it increased in Toyonoka' and 'Hokowase' as the fruits ripened. 3. In 'Reiko' and 'Toyonoka', the variation of total sugar content in the fruits grown by open culture was larger than that of fruits grown under forcing culture. 'Toyonoka' fruit had large amounts of sugars with small variations during the harvest as compared to 'Reiko'. 4. The amount of sugars in strawberry fruit varied among cultivars, harvest years, cropping types and developmental stages of fruit, but the ratio of each sugars to total sugar content was nearly constant. The sugar composition of each cultivars seems to be a heritable characteristic, unaffected by the environment.