Hochberg Uri (uriho9842@yahoo.com), Degau Asfaw (degua3@gmail.com), Fait Aaron (fait@bgu.ac.il), Rachmilevitch Shimon (rshimon@bgu.ac.il)

The Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Israel.

Grapes (Vitis vinifera) are well adapted to arid and semiarid environments due to their extensive deep root system and tightly regulated drought avoidance mechanisms. Since regulated water deficit is known to improve quality of wine grapes, many of the world vines are regularly deficiently irrigated. It was established that different cultivars of grapes choose different strategies to deal with drought stress. Based on their strategy, varieties where divided to isohydric and anisohydric.

In the presented research hydraulic behavior of two grapevine varieties, Cabernet Sauvignon (isohydric) and Shiraz (anisohydric), were studied in both field and green house conditions. In both locations different irrigation stress treatments were given. Standard physiological methods and metabolic analysis methods (GCMS, LCMS) were used to investigate plant response to water stress.  Differences between cultivars and between treatments were observed in both the physiological and the metabolic levels. Shiraz depleted the soil water faster, reached lower water potential and kept stomata conductance higher. In Cabernet Sauvignon stress tolerance mechanisms were activated at higher soil water content; Stomata conductance decreased and soil water content remained higher, allowing higher leaf water potential. Metabolically, both cultivars had a similar reaction to stress, amino acids levels increased and organic acids level decreased. Shiraz demonstrated a bigger metabolic change, which was particularly notable in sugar metabolism.  

by the combination of physiological and metabolism research, allows a deeper understanding of the an/isohydric phenomena. The different response of different grapevine cultivars to water limitations, suggests that irrigation regimes should be adjusted specifically per cultivar in order to save water and improve yield and quality.