Phenology and fruit quality of kiwifruit under different environments

Weekly phenology and fruit quality data were taken over four years on two Sardinian areas covering the geographical and climatic range of the region. Accumulated Degree-Days were calculated using the single sine method in order to check the response of kiwifruit to different environmental conditions. The accuracy of the Degree-Day (degrees D) model was tested in terms of variability of accumulated heat and occurrence of phenological stages. The analysis of the degrees D model results showed that 10 degrees C threshold provides a better prediction of phenological stage occurrence in comparison to the 8 degrees C threshold. Regression of the dates of phenological stage occurrence and number of accumulated degrees D showed that the model accounted for 96% of the variance in the two sites. Fruit quality data showed the effect of different air temperature range on acid and soluble solids content during the ripening stage.