Changes in non-structural carbohydrate concentration in 1-year-old shoots of 'Braeburn' apple (Malus domestica) over two consecutive years

This paper presents patterns of change in non-structural carbohydrate concentrations of 1-year-old shoots over a 2-year period for 'Braeburn' apple trees (Malus domestica) growing in the Waikato region of New Zealand. Carbohydrates analysed by enzymatic analysis included starch, sorbitol, sucrose, glucose, and fructose. Sorbitol concentrations were found to be higher than starch for most periods of the year and sorbitol comprised the majority of the total carbohydrates. Starch concentrations were never completely depleted, even during periods of rapid growth. These patterns of carbohydrate change were similar to those reported from Northern Hemisphere studies for a variety of deciduous fruit tree species, indicating that carbohydrate changes in New Zealand trees are comparable with trees worldwide, despite the long period of leaf retention after harvest in New Zealand.