2012 Annual Report
From morphological and anatomical aspect, severe water stress reduced leaf size. Zinfandel showed higher leaf size than Grenache. For leaf thickness, with increasing water stress, Grenache increased leaf thickness to reduce surface to volume which is a positive strategy to resist drought. Water stress reduced stomatal pore areas significantly but not stomatal density. Palisade cell length of Zinfandel was very responsive to water stress while Grenache showed longer palisade cell length under water stress. Also, water stress affected intercellular air spaces of the three cultivars with Grenache showing the highest values. Water stress did cause differences in their morphology and anatomy except leaf vein density of Zinfandel and Grenache. Cavitation occurred under the severe water stressed treatment of the three cultivars showing all of them were vulnerable to water-stress induced cavitation. Water stress in general altered the fruit composition; however, more research using different stress levels is needed to better understand the water stress effect on fruit composition. Among the three, Grenache performed the best followed by Cabernet Sauvignon and Zinfandel in terms of grapevine physiology, morphology and anatomy. Based on this study, Grenache was very adaptive to drought conditions. Thus, its resilience can be exploited to make planting recommendations in sites with limited availability of water. The information gathered from this study can be useful for guiding targeted irrigation strategies, which focus on delivering water to the grapevines only when it is necessary in established vineyards. Furthermore, the results of this research will assist vineyard managers to manage water efficiently in planted vineyards by targeting cultivars that show resilience to drought. Such approaches have the potential to improve crop quality while at the same time reducing water use. For new growers, the information will help them guide vineyard design and subsequent development. Additionally, this research has potential benefits to environment which include improvement in biodiversity and air quality (dust control), reduction in land degradation and improvement in productive capacity of the land, and finally having such land planted with grapevines contributes to visual (aesthetic) and landscape qualities.