Variation in carbon content and size in developing fruit of Actinidia deliciosa genotypes

Abstract. This study identifies the developmental processes contributing to variation in green-fleshed kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson var. deliciosa) fruit dry matter content (DM) and fresh weight (FW) by comparing genotypes with either high or low final DM. Results are compared with the model for fruit development, the tomato (Solanum lycopersicumL.). Differences infinal compositionwere attributable to a higher rate of starch accumulation from 70 days after anthesis in high DM genotypes, with no other consistent differences in accumulation of soluble sugars or organic acids. High DM genotypes had 70 % higher starch content and differed from lowDM genotypes in the allocation of carbonbetween storage andother components.DMwasnegatively correlatedwithfinal fruit FWonly in highDMgenotypes, whereas starchwas a constant proportion of dryweight (DW), suggesting a dilution effect rather than an interaction between fruit size and carbohydratemetabolism. Comparedwith tomato, the organic acids, particularly quinic acid, contributedmore to estimated osmotic pressure during growth in FW than the soluble sugars, regardless of final composition or size. Seed mass per unit FW was highest in high DM genotypes, suggesting a previously unrecognised role for kiwifruit seeds i