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EasternWineLab_Mar09.qxp 1/22/09 9:47 AM Page 1 WineEast EASTERN WINE LABS Serving the Analytical needs of East Coast Wineries WWW.EASTERNWINELABS.COM Ph 609-859-4302 Cell 609-668-2854 chemist@easternwinelabs.com AOAC Member The root system effects vine-performance metrics such as yield, berry composition and scion physiology. to tolerate drought. Seasonal root proliferation in a directed manner could increase the water supply function of roots independent of total root area and represents a mechanism whereby water supply to demand could be increased. To address this issue, seasonal root proliferation, stomatal con- ductance (gs) and whole root system hydraulic conductance (kr) were investigated for a drought-tolerant rootstock (Vitis berlandieri x V. rupestris 1103p) and a non-drought-tolerant rootstock (V. riparia x V. rupestris 101-14 Mgt), upon which had been grafted the same clone of Merlot. leaf water potentials for Merlot/1103p were +0.15 Mpa higher than Merlot/101-14 Mgt during spring, but dropped by ≈ -0.4 Mpa from spring to autumn and were lower by -0.15 Mpa than for Merlot/101-14 Mgt. Surprisingly, gs of Merlot on drought- tolerant 1103p was less down-regulated, and canopies maintained evaporative fluxes ranging from 35-20 mmol/vine/s during the di- urnal peak from spring to autumn, respectively, three times greater than those measured for Merlot on drought-sensitive 101-14 Mgt. drought-tolerant 1103p grew more deep roots during the warm summer dry period, and the whole root system conductance (kr) increased during that same time period. The manner in which drought tolerance was conveyed to the drought-sensitive clone appeared to arise from deep root proliferation during the hottest and driest part of the season, rather than through changes in xylem structure, xylem density or stomatal regulation. This information can be useful to growers on a site-specific basis in selecting root- stocks for grape clones that may be particularly drought-sensitive. M.M. Alsina, D.R. Smart, T. Bauerle, F. de Herralde, C. Biel, C. Stockert, C. Negron and R.J. Save, Experimental Botany 62:99-109 (2011). Contact the senior author: Department of Viticulture and Enology, University of California, Robert Mondavi Institute North, 595 Hilgard Lane, Davis, CA 95616. WE Wines & Vines JULY 2012 65 Carolina Wine Supply The Southeast's Most Complete Winery Supply Company Order Now For Harvest! Enartis - Yeast, Nutrients & Enzymes Currently in Stock - Barrel Racks www.CarolinaWineSupply.com 336-677-6831 Yadkinville, NC