Hydraulic anatomy, cavitation susceptibility and gas-exchange of several grapevine cultivars of different geographic origin

Differences in hydraulic anatomy may account for grapevine cultivar differences in stomatal sensitivity. Relationships among hydraulic conductance in stems and petioles, susceptibility to embolism formation in the xylem and stomatal responsiveness of grapevine cultivars grown in pots and the field to water deficits were investigated. Four cultivars were chosen that are typically grown in different areas. of Europe varying in large part in water supply; 'Airen' (Spain), 'Grenache' (Spain/France), 'Syrah' (France) and 'Silvaner' (Germany). The decrease in stomatal conductance occurred concomitant with an increase in ultra-sound acoustics emission signals (AEs) for all cultivars as soil water became limiting, but at very different absolute emission rates. 'Silvaner' and 'Airen' were the most sensitive to xylem embolism formation in the stem during the initial dry-down phase of the pot experiment. After reaching a maximum, AEs decreased until stomatal closure was complete in 'Silvaner' and 'Airen' but not in 'Grenache' and 'Syrah'. Hydraulic conductance of internode segments was greatest for 'Airen' and 'Silvaner', followed by 'Grenache' and 'Syrah'. For example at a plastochron index of 20 (similar to equal to the node position basal to the shoot apex), 'Silvaner' had a 4-fold higher conductance than 'Syrah' in the field. When stomatal conductance approached zero, 'Syrah' had exploited most of the plant available water and 'Silvaner' and 'Airen' the least. The data indicate that water use strategies of grapevine cultivars are correlated with plant architecture and anatomy.