Effects of Glucose and Mannose on Nutrient Absorption and Fruit Quality in Peach (Prunus persica L.)

The objective of this study was to investigate the effects of the exogenous application of glucose and mannose on nutrient absorption and quality in peach fruit. Pot and field experiments were conducted to investigate the nutrient absorption of peach trees at the seedling stage and nutrient absorption and quality of peach fruit at the fruiting stage. The pot experiments used KH2PO4 P 200 mg kg−1 as the control, and glucose and mannose (100, 200, and 400 C mg kg−1) were combined with KH2PO4 P 200 mg kg−1. In the field experiments, two peach varieties were used as experimental cultivars, and 2.5, 5, and 10% glucose and mannose (ratio of sugar to total fertiliser weight) were combined with nitrogen, phosphorus, and potassium (NPK) fertilisers. Glucose application stimulated N absorption by peach seedlings; increased glucose application resulted in increased N content in the soil and leaves. The combined effects of glucose and mannose application on the nutrient content of peach seedling leaf and rhizosphere soil showed that mannose could promote nutrient absorption by peach seedlings. Glucose and mannose application improved peach fruit quality, such as by increasing the contents of soluble sugar and vitamin C (Vc) compared to the control. The application of 2.5 and 5% glucose increased the K content of peach fruit, and that of 5 and 10% mannose increased the average fruit weight. Nutrient content and fruit quality were generally higher following mannose treatment than glucose treatment, and fruit quality was better under low sugar concentration than under medium and high sugar concentration. Therefore, mannose has greater potential than glucose as a specialised fertiliser for peach fruits.