Improving vine performance by modifying daily light interception patterns in vertically shoot positioned grapevines

摘要

Vertically shoot positioned (VSP) vines are often planted in rows, offering the possibility to modify patterns of light interception over the day by leaning vines. Since vapour pressure deficit in the early afternoon is higher than early in the morning, decreasing the amount of radiation that the canopy receives in the afternoon could be used to reduce transpiration in those moments when the evaporative demand is higher. A field experiment was initiated in a north-south oriented vineyard where rainfed and deficit-irrigated vines were trained either as traditional VSP or with the canopy leant 30° towards the west (WSP), which were trained the same except for the inclination. In addition, young non-fruiting potted vines with full watering were also submitted to either VSP or WSP training. In the field, in both watering regimes, WSP vines had a cluster weight that was 21% higher than the VSP ones due to the higher berry number per cluster. In the pot experiment, vine dry matter production was 10% higher in the WSP than in the VSP, while the initial whole vine water use was similar. At the end of the experiment, the WSP transpired 8% more water than the VSP because they had increased shoot growth. However, when transpiration was expressed on a per leaf area basis, WSP and VSP vines had similar values. The long-term water use efficiency (dry matter produced/vine transpiration) was similar in both trainings. Overall it is concluded that leaning vines towards the west can improve vine yield and dry matter production. More effort is needed to corroborate the present results in further seasons and to test other leaning orientations that could modify vine transpiration.