Variations in Sugar and Organic Acid Content of Fruit Harvested from Different Vaccinium uliginosum Populations in the Changbai Mountains of China

Sugar and organic acid contents as well as sugar-to-acid ratio of fruit are important factors affecting fruit quality and processing. In this study, we compared sugar and organic acid contents of Vaccinium uliginosum (bog bilberry) fruit harvested from 100 plants across 10 wild populations growing in the Changbai Mountains of China. Correlation of sugar and acid contents with the spatial distribution of these populations was accessed. Germplasm with high sugar and low acid with potential for use in future breeding was also identified. Results showed that sugar and organic acid contents varied among different V. uliginosum populations in the Changbai Mountains. Fructose (18.60–38.54 mg·g −1 ) and glucose (15.77–35.08 mg·g −1 ) were the main sugars, whereas quinic (16.06–20.97 mg·g −1 ), citric (10.39–14.96 mg·g −1 ), and malic (4.28–7.47 mg·g −1 ) acids were the main organic acids in V. uliginosum . The first population collected in the Dongfanghong forest farm (lat. 42°00′N, long. 128°03′E) showed the highest average sugar content and sugar-to-acid ratio among the sampled populations. Moreover, total sugar content and sugar-to-acid ratio of Sample 7—Population 1, which is located at Manjiang forest farm (lat. 41°09′N, long. 127°05′E) was much higher than the other 99 samples, making this sample representative of important germplasm for breeding. Altitude and latitude were important environmental factors affecting sugar and organic acid contents. Fructose, glucose, and total sugar contents were positively correlated with altitude and negatively correlated with latitude. Oxalic acid content and sugar-to-acid ratio were positively correlated with altitude, and there was no significant correlation between organic acid contents and latitude.