Sorbitol and Sugar Composition in Plum Fruits Influenced by Climatic Conditions

The aim of the study was to evaluate changes of sorbitol, glucose, fructose, sucrose, and total sugars of plum fruits in different years under different climatic conditions i.e. air temperature and precipitation. The cultivars investigated in the research were: Topstar, Toptaste, Jojo, Haganta, Tophit, and Top 2000. The fruits were harvested at optimal stage of maturity in the experimental orchard of the Agricultural Institute Osijek. Content of glucose, fructose, sucrose, and sorbitol in the fruits were identified and quantified by high performance liquid chromatography (HPLC). Significant differences were found between sucrose, glucose, fructose, and sorbitol depending on climatic conditions and cultivar. Sucrose was the highest in almost all years. Glucose was the predominant sugar in cultivars Jojo and Top 2000. Fructose and sorbitol contents were lower than sucrose and glucose. Average sugar contents in 2008-2012 period were compared with respect to climatic conditions. A significant effect of year was found for sucrose, sorbitol, total sugar, and dry matter, whereas no effect was found for glucose and fructose contents. Individual sugar contents correlated significantly with each other. The principal component analysis (PCA) showed that plum cultivars were clearly differentiated according to variability of sugar in fruit caused by climatic conditions. The obtained results highlighted that climatic conditions may have significant effect on plum fruit quality and, therefore, it is important to have adequate testing before recommending a cultivar for planting.