Articles
The effect of roots and leaves on bud burst of apple shoots under forcing conditions during dormancy
Article number
1366_52
Pages
421 – 428
Language
English
Abstract
Forcing defoliated, excised, one-year-old shoots to bud burst is the standard in dormancy research and this method has been used successfully to describe dormancy progression patterns in deciduous trees, especially during the release from bud dormancy, and in the evaluation of rest-breaking agents.
In warm fruit growing regions, leaves are present well into winter and shoots must be defoliated prior to forcing.
The entrance into bud dormancy under these conditions is protracted compared to colder regions.
The possible effects of the leaves and roots on the bud dormancy could influence findings.
To test the validity of the shoot assay and the effects of the roots and leaves on the bud dormancy, we compared the dormancy curves and bud burst results from: a) the traditional shoot assay (excised, defoliated shoots) against, b) the forcing of single shoot, intact, potted trees, as well as c) single shoot, defoliated potted trees, and d) excised shoots with leaves, during dormancy over two consecutive seasons.
To assess the shoot assay as a proxy during the evaluation of rest-breaking agents we tested a rest-breaking treatment before spring using a) excised shoots and b) single shoot, potted trees.
Leaves influenced dormancy during the entrance into dormancy in both excised shoots and intact trees.
Trees were consistently more dormant than shoots as the season progressed indicating that roots could possibly also contribute to the inability to grow.
A significant, strong correlation between the progressions of dormancy of excised, defoliated shoots and defoliated trees were found in both trial seasons suggesting that the shoot assay is a good proxy for dormancy progression caused by factors within the bud itself.
Using the shoot assay to screen rest-breaking agents showed the same significant time advancement of bud burst, but gave conflicting results in terms of maximum bud burst between the two trial seasons.
More research is suggested to understand this phenomenon.
In warm fruit growing regions, leaves are present well into winter and shoots must be defoliated prior to forcing.
The entrance into bud dormancy under these conditions is protracted compared to colder regions.
The possible effects of the leaves and roots on the bud dormancy could influence findings.
To test the validity of the shoot assay and the effects of the roots and leaves on the bud dormancy, we compared the dormancy curves and bud burst results from: a) the traditional shoot assay (excised, defoliated shoots) against, b) the forcing of single shoot, intact, potted trees, as well as c) single shoot, defoliated potted trees, and d) excised shoots with leaves, during dormancy over two consecutive seasons.
To assess the shoot assay as a proxy during the evaluation of rest-breaking agents we tested a rest-breaking treatment before spring using a) excised shoots and b) single shoot, potted trees.
Leaves influenced dormancy during the entrance into dormancy in both excised shoots and intact trees.
Trees were consistently more dormant than shoots as the season progressed indicating that roots could possibly also contribute to the inability to grow.
A significant, strong correlation between the progressions of dormancy of excised, defoliated shoots and defoliated trees were found in both trial seasons suggesting that the shoot assay is a good proxy for dormancy progression caused by factors within the bud itself.
Using the shoot assay to screen rest-breaking agents showed the same significant time advancement of bud burst, but gave conflicting results in terms of maximum bud burst between the two trial seasons.
More research is suggested to understand this phenomenon.
Authors
E.D. Louw, L. Allderman, W.J. Steyn, N.C. Cook
Keywords
Malus × domestica Borkh., rest-breaking, shoot assay
Groups involved
- Division Plant-Environment Interactions in Field Systems
- Division Temperate Tree Fruits
- Division Temperate Tree Nuts
- Division Tropical and Subtropical Fruit and Nuts
- Division Horticulture for Development
- Division Vine and Berry Fruits
- Division Precision Horticulture and Engineering
- Commission Agroecology and Organic Farming Systems
Online Articles (58)