Effect of bud load and canopy management on growth and yield components of grape cv. 'Cardinal' under mild climatic conditions of Agadir area of Morocco

The effect on growth and development of different bud loads (14, 20, 30 and 40 latent buds per vine) combined with shoot topping at the beginning or at the end of flowering was studied on 6 years old 'Cardinal' grapevine. Topping treatments were done at the level of the 10(th) leaf. The vines were growing under winter mild climatic conditions of Agadir area (Morocco). The experiment showed that bud fertility and vegetative growth (bud burst and secondary shoot development) were reduced with the increase of bud number per plant. Sprouting capacity is reduced by 76.7 to 53.7% when bud load increases from 14 to 40 buds; whilst there is a 63.8% increase in yield, due to the number of bunches per vine. Shoot topping enhances canopy development through stimulation of lateral bud growth. This enhancement is higher when bud load was low and topping occurs at the early stage. In vines with a load of 20 buds, topped at the end of flowering, grape production was improved by 31.3% with a 6.6% reduction in soluble sugar content. These results show that the production of vine grown under conditions with lack of chilling may be improved by the adoption of an appropriated plant management with the aim of establishing a balance between vegetative growth and fruit development.