Fruit growth in kiwifruit ( Actinidia deliciosa): Patterns of assimilate distribution between laterals

Abstract

Different patterns of assimilate translocation were demonstrated in the kiwifruit vine, such that any shortage in the local supply of carbohydrate for fruit growth within a lateral was readily met by surplus carbohydrate from other fruiting or non-fruiting laterals. Assimilate transport occurred in either a basipetal or acropetal direction, depending on the relative positions of the regions of carbohydrate surplus and shortage. Translocation over 7 nodes distance in 1-year-old stems was observed. Fruit on laterals with low leaf-fruit ratios (1:1) imported the most 14C label from neighbouring laterals. The partitioning of 14C assimilate towards these fruit increased with the physical proximity of the laterals. A non-equivalence between girdled and non-girdled shoots was observed. While fruit growth was increased by the presence of non-fruiting laterals in girdled canes, fruit size was reduced by large leaf numbers on non-girdled canes.