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| Authors: | R. Rageau, J.C. Mauget |
Abstract:
Development of vegetative buds of peach, apple, and walnut was studied during one or more dormant seasons.
Potted trees were transferred to an air-conditioned greenhouse (minimum temperature 15°C) after varying periods of exposure to ambient cold temperatures.
The growth capacity of isolated buds, expressed as the time required for bud break on single node cuttings at 25°C, was determined at regular intervals.
Warm temperatures applied when the intensity of rest was greatest first reinforced rest, but eventually broke it, although growth was delayed in comparison with trees held outdoors.
Warm temperatures applied after rest began slowed, but did not prevent the breaking of dormancy.
Following longer exposure to cold temperatures, warm conditions hastened bud break at 25°C, indicating that many buds had recovered their full capacity to grow.
The less chilling received, the higher the mean days to bud break at 25°C, and the greater the variability.
Proximal buds grew more readily than did distal ones.
Phenological development paralleled bud break, the earlier trees were transferred to the greenhouse, the later they produced leaves and more variable the foliation.
Development was normal only in trees transferred in January.
We conclude that the abnormalities in phenological development of insufficiently chilled trees were not due to inefficiency of warm temperatures in breaking rest.
As a working hypothesis we suggest that correlative inhibition of the growth of certain buds occurs as soon as the first buds begin to grow, and that this may explain our results.
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