TY - JOUR T1 - The Influence of <em>Vitis riparia</em> Rootstock on Water Relations and Gas Exchange of <em>Vitis vinifera</em> cv. Carignane Scion Under Non-Irrigated Conditions JF - American Journal of Enology and Viticulture JO - Am J Enol Vitic. SP - 137 LP - 143 DO - 10.5344/ajev.2000.51.2.137 VL - 51 IS - 2 AU - M. Padgett-Johnson AU - L. E. Williams AU - M. A. Walker Y1 - 2000/01/01 UR - http://www.ajevonline.org/content/51/2/137.abstract N2 - A two-year study examining the water relations and gas exchange of Vitis riparia Michaux, Vitis vinifera L. cv. Carignane, and grafted vines comprised of a Carignane scion on V. riparia rootstock was conducted in a non-irrigated vineyard at the University of California Kearney Agricultural Center, near Fresno, California. During the two seasons the data was taken (1992 and 1993), soil water content of the trial plot was similar and decreased during the growing season. Pre-dawn leaf water potential (ψleaf), pre-dawn leaf osmotic potential (ψπ), and stem water potential values (ψstem) did not differ among the treatments. Net carbon dioxide assimilation (A), stomatal conductance (gs), and instantaneous water use efficiency (WUE) were influenced by treatment, and behaved similarly comparing the two years. Carignane vines had significantly greater gas exchange values than either V. riparia or the grafted vines, but the latter two were similar to one another. These results indicate that under non-irrigated conditions, rootstock can modify gas exchange behavior of the scion cultivar even though vine water status was not altered. ER -