ISHS Acta Horticulturae 146: International Workshop on Controlling Vigor in Fruit Trees
EFFECTS OF CROPPING ON TREE VIGOUR |
| Author: | J.E. Jackson |
| Abstract:
Increased cropping is usually accompanied by decreased vegetative growth in the same year, with reduced dry-weight increment of leaves, stems, trunks and roots. The threshold crop below which no such effects occur is very low, increased leaf photosynthetic efficiency in heavily cropping trees not being great enough to prevent the check to vegetative growth. Effects on shoot growth appear to be a function of total fruit yield, not of number of fruits per se. Root growth is very sensitive to effects of cropping and can be almost totally stopped. The total length of shoots growing in the year following a heavy crop is reduced to about the same extent as is shoot growth in the cropping year. The cumulative effects of cropping are such as to lead to great differences in size between trees deblossomed from planting and those allowed to crop normally. Trees on dwarfing rootstocks are much heavier cropping in relation to their size than trees on vigorous rootstocks but this only partially explains rootstock effects on vigour. Deblossomed trees on M.9, for example, being much smaller than trees on M.16 deblossomed over the same period from planting. | |
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