Flowering time determines the weight and composition of Actinidia chinensis var. chinensis ‘Zesy002’ kiwifruit

Abstract Consistently high flavour in fruit of a recently released commercial gold-fleshed kiwifruit cultivar ‘Zesy002’ is important for consumer acceptance. We hypothesised that variation in fruit weight and quality was determined during flower differentiation, and that date of flower opening and flower type (terminal or lateral) were important indicators. We determined whether time of flowering (early 5% open, mid 50% open and late 95% open) and flower type (terminal or lateral) influenced fruit weight, fruit maturity and fruit composition over two growing seasons. Fruit that developed from early-opening terminal flowers were 12–13 g heavier than those that developed from late-opening terminal flowers. Measurements in the second season suggested that this difference in fruit weight was related to ovary weight. Early-opening flowers were produced on shoots from smaller diameter canes than mid- and late-opening flowers. The soluble solids content, firmness and flesh colour of fruit was related to the period of fruit development, so late-opening flowers produced less-mature fruit as kiwifruit are harvested at a single date. Early-opening terminal and lateral flowers had significantly more outer pericarp tissue than fruit that developed from late-opening terminal flowers. This difference in tissue proportion was associated with 1–2 units higher fruit dry matter content and higher sugar:acid ratios in ripe fruit juice. Fruit from early-opening lateral flowers were smaller but had similar maturity and sugar:acid ratios to fruit from early-opening terminal flowers. These results suggest that competition during flower differentiation in spring influences the weight and composition of the ovary and fruit attributes at harvest. Hence, these attributes of ‘Zesy002’ fruit could be managed by manipulating flower development in spring.