ISHS Acta Horticulturae 640: XXVI International Horticultural Congress: Viticulture - Living with Limitations
INFLUENCE OF WATER STRESS AND CROP LOAD ON THE PHYSIOLOGY AND THE PRODUCTIVITY OF TEMPRANILLO UNDER SEMIARID CONDITIONS |
| Authors: | J.A. Rubio, M.V. Alburquerque, J. Yuste |
| Keywords: | yield, must composition, stomatal conductance, transpiration, photosynthesis |
| Abstract:
The influence of water stress and crop load on the physiology and productivity of the red Tempranillo variety was studied. Effects on yield and grape ripening were also studied over four years (1994-1997). The vineyard is located in the semiarid Duero River region (Spain). Vines were spaced at 3.0 x 1.6m and were vertical-trellis trained with spur pruned bilateral cordons. In the non-irrigated treatments the only water available was from rainfall, whereas in irrigated treatments, irrigation was applied at a rate of 0.4 ETo from June to September. The crop load was controlled by cluster thinning at the beginning of the veraison, taking out 33% (1994) and 40% (1995-1997) of all clusters in each vine. Water stress in the non-irrigated plants resulted in reduced of the levels of stomatal conductance, transpiration and photosynthesis in comparison with the irrigated plants. These differences were apparent during most of the ripening process. Non-irrigated plants accumulated less dry matter in their aerial parts, and produced lower yields. The fruit sugar content in response to irrigation was higher than without irrigation to below a certain yield level. When this yield level was reached the tendency between treatments became the opposite. The total acidity was higher in the irrigated vines, whereas the pH was lower. Cluster thinning did not provoke significant differences in physiological activity, although net photosynthesis was sometimes higher in non-thinned irrigated vines. No-thinned vines accumulated more dry matter, due to the higher number of clusters, and produced higher yields. Vines with lower yields produced fruit with higher sugar content and lower acidity. | |
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