ISHS Acta Horticulturae 557: VII International Symposium on Orchard and Plantation Systems
LIMITED AVAILABILITY OF PHOTOASSIMILATES: EFFECTS ON THE ABSCISSION OF SWEET CHERRIES |
| Authors: | C.J. Atkinson, M.A. Else, A.P. Stankiewicz, A.D. Webster |
| Keywords: | abscission, cherry, girdling, photoassimilates, Prunus |
| Abstract:
An improvement in our understanding of the underlying causes of embryo abortion and fruitlet abscission is essential if effective remedies to this problem are to be devised. The aim of this study was to address the effect of limiting the availability of leaf-derived assimilates, during critical stages of fruitlet development, on the severity of fruitlet abscission (run-off). This was achieved by ‘isolating’ each spur unit from the rest of the tree by girdling (removing the phloem connections) either side of the unit. In this way, the developing fruitlets within the associated cluster would only be able to derive their assimilates from the associated spur leaves. Spur units with different total leaf areas and variable numbers of developing fruitlets were chosen to achieve a wide range of potential source to sink strengths. The experiments were conducted on 6-year-old trees of the sweet cherry cultivar Lapins grafted on ‘F 1090’ rootstocks. When spurs were stem girdled in June, it appeared that the total fresh weight rather than the number of fruit in a cluster was limited by the amount of photosynthetic area of the associated spur leaves. The average individual fresh weights of fruit in a cluster were, however, limited by the number of fruit within that cluster. Initial conclusions suggest that fruit size, not retention, appears to be limited by the availability of leaf-derived assimilates in June. | |
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