Reserve status and growth arrest phenomenon (GAP) incidence of sultanina H5 in the Lower Orange River region
PROJECT TITLE: Reserve status and growth arrest phenomenon (GAP) incidence of Sultanina H5 in the Lower Orange River region as affected by post-harvest pruning
Project Leader: Jan Avenant (ARC Infruitec-Nietvoorbij)
Contact: avenantj@arc.agric.za
Duration: 1 April 2018 to 31 March 2023
Problem identification and project Objectives:
Pruning during the post-harvest period is a cultivation practice widely used by several table grape producers in South Africa. Producers believe that this practice will improve post-harvest reserve accumulation in the current season and bud fertility in the following season and also reduce the total time required for pruning. The occurrence of the growth arrest phenomenon (GAP) is often linked to continuous post-harvest growth. Rootstock differences between GAP occurrences in scion cultivars are reported for current rootstock trials and in the industry (Avenant, 2000).
There is a need to establish the link between vine reserve status, continued post-harvest growth
activity, grape vine vigour and phenology, pruning time (post-harvest and winter) and GAP. Increased input costs of table grape production, force producers to evaluate the return on investment of each cultivation practice, such as post-harvest pruning. Any manipulation should only be done if is it scientifically proven to be necessary, as well as economically justified.Overall objectives of this study are to:
- Determine the carbohydrate reserve status of Sultanina H5 on Ramsey rootstock as affected by pruning treatments;
- establish the link between carbohydrate status of Sultanina H5; and
- establish the link between the phenological cycle and seasonal pattern of carbohydrate status.