Articles
EFFECT OF TEMPERATURE AND LENGTH OF COLD STORAGE OF NURSERY PLANTS ON THE SUBSEQUENT DEVELOPMENT OF YOUNG APPLE TREES
Consequently, after planting, the young tree tends to grow only the 2 or 3 apical buds located just below the pruning cut.
Chemical treatment for bud break can supply this chilling requirement.
However, many of these buds do not develop well and consequently produce spurs.
The chilling requirement can also be achieved by storing the young apple trees into cold storage room from July to September after removing them from the nursery.
Trees of cv.
Gala and Fuji were stored in cold room at 2°C and 6.°C for periods of 0 (control), 15, 30, 45 and 60 days.
The trees were divided into two groups: one received a chemical treatment (mineral oil 4% + DNBP 0.16%) for bud break, and the other group did not.
Results show that a cold storage treatment during 45 and 60 days, either at 2.°C or at 6.°C were the two best treatments to break bud dormancy.
Storage periods of less than 30 days were not sufficient to break bud dormancy, requiring an additional chemical treatment.
The longer the period in cold storage, the higher the number of shoots with more than 20 cm in length, and the higher the trunk transversal area at 20 cm above ground, respectivelly.
These results represent areas with less than 600 chilling hours (7.2.°C).