CARBOHYDRATE DYNAMICS IN KIWIFRUIT

Rates of fruit growth, on-vine changes in the soluble and insoluble ca rbohydrate pools, and subsequent changes during storage were examined on kiwifruit from vines having moderate to very high crop loads (20-50 fruit m(-2)). In accord with previous studies, vines carrying the hig hest loads exhibited a 18% decrease in mean fruit weight and a two-fol d increase in total yield compared with those having the lowest crop l oads. Rates of dry-matter accumulation in the fruit varied in proporti on to total yield and remained constant over the entire season - a res ult that deserves further investigation. Effects of crop loading on th e carbohydrate composition of fruit were small and after reviewing the available literature we conclude that the primary determinants of fru it composition are genetic and climatic. Relationships between the var ious fruit quality variables were used to develop a predictive model o f soluble solids concentration of fruit at eating ripeness from harves t measurements of fruit density (weight per unit volume) or dry matter . The accuracy of these predictions are of the order of 1% (w/v). The rate of change in soluble solids during storage at 0 degrees C is show n to follow a simple exponential function of time with a time constant of 20 d.