ISHS Acta Horticulturae 297: II International Symposium on Kiwifruit
THE GROWTH AND COMPETITIVE ABILITY OF ACTINIDIA DELICIOSA ‘HAYWARD’ FRUIT : CARBOHYDRATE AVAILABILITY AND RESPONSE TO THE CYTOKININ-ACTIVE COMPOUND CPPU. |
| Authors: | D.J. Woolley, G.S. Lawes, J.G. Cruz-Castillo |
| Keywords: | cytokinins, source strength, sink strength, cell activity |
| Abstract:
Interaction between leaf:fruit ratio and girdling indicated that the competitive ability of the fruit for carbohydrates often limits final fruit size. It was found that CPPU can increase the amount of carbon allocated to fruit growth and produce a stimulation of both cell division and cell expansion. Changes in cell number and size in the outer pericarp, inner pericarp and core were determined at regular intervals after the application of CPPU. Growth increases of about 35 g per fruit occurred at both moderate and low crop loads and at both high and low seed numbers. Only when seed numbers fell below about 100 seeds per fruit was the response to CPPU diminished. Evidence is presented that the fruit is a poor competitor for the additional carbon required to produce large fruit and that it is this poor competitive ability, rather than a limiting supply of carbohydrate, that may often reduce fruit size. The benefits of using CPPU as a physiological probe to improve our understanding of factors controlling fruit growth and final size is discussed. | |
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