PT - JOURNAL ARTICLE AU - A. Schubert AU - M. Restagno AU - V. Novello AU - E. Peterlunger TI - Effects of Shoot Orientation on Growth, Net Photosynthesis, and Hydraulic Conductivity of <em>Vitis vinifera</em> L. cv. Cortese AID - 10.5344/ajev.1995.46.3.324 DP - 1995 Jan 01 TA - American Journal of Enology and Viticulture PG - 324--328 VI - 46 IP - 3 4099 - http://www.ajevonline.org/content/46/3/324.short 4100 - http://www.ajevonline.org/content/46/3/324.full SO - Am J Enol Vitic.1995 Jan 01; 46 AB - Grapevine (Vitis vinifera cv. Cortese) plants were grown in containers, and their single shoot was trained either upwards or it was bent to a horizontal or downward position. Clusters and lateral shoots were removed. Downward shoots had less leaf area and a lower stem diameter than did horizontal and upward shoots. In downward shoots, net photosynthesis and stomatal conductance, measured at maximum irradiance, were lower than in horizontal and upward shoots; these differences were more evident at the middle nodes of the shoot. The substomatal CO2 concentration was not affected by shoot orientation, suggesting a non-stomatal limitation of photosynthesis. This hypothesis was supported by a reduced protein content and a lower activity of ribulose 1,5-bisphosphate carboxylase/oxygenase in leaves of downward shoots. Downward shoots also had less xylem transectional area and a lower hydraulic conductance than did horizontal and upward shoots. Conductance was more reduced at the point of bending than at other internodes.