Soluble Sugar Content in Fruit of Nine Wild and Forty-one Cultivated Strawberries

Abstract

Fresh strawberry fruits from 9 wild strains and 41 cultivars were anlayzed for sugar composition and evaluated by the principal component analysis. 1. Sucrose, fructose, and glucose are the major sugar components of strawberry fruits. The differences in content and compostion of sugars among strawberries were examined. Forty-one cultivars were classified into 4 groups by the principal component analysis. Cultivars, such as 'Toyonoka' in Group 1 contain a high percentage of fructose and glucose and high content of total sugar ; such as Group 2 included 'Kogyoku', which possesses a high percentage of sucrose ; Group 3 amplified by 'Nyoho' is intermediate between Group 1 and 2 ; whereas Group 4 cultivars, such as 'Kaho' has a high percentage of fructose and glocose, but low total sugar. In wild strawberries, Fragaria vesca with the exception of 'White' and F. Chiloensis is characterized by a sugar compostion with nearly equal percentages of sucrose, fructose and glucose. F. Virginiana is characterized by a small amount of total sugar and a low percentage of sucrose. 2. Sugar content and vegetative characteristics in 41 cultivars revealed that total sugar content correlates positively with plant height, leaf area and soluble solid content. Fructose or glucose content correlates negatively with the number of days from flowering to harvest. Consequently, we conclude that sugar content is an important factor in breeding high quality, sweet strawberry cultivars.