2010 Annual Report 1a.Objectives (from AD-416) 1. Understand the dynamics of water flow in the current season shoot of vines of a given vigor by examining the anatomical features of the xylem along the shoot length at different intervals (bottom, middle, and top of the shoot). This will provide insights into how the spatial differences in xylem anatomy are related to water movement in a growing shoot during the current season. 2. Examine xylem anatomy of trunks, cordons, and current season shoots with different vigor levels. 1b.Approach (from AD-416) Plant material to carry out the anatomical work for this proposal will be obtained from field-grown grapevines (Vitis vinifera L. cv. Merlot). The purpose of measuring xylem anatomical features is to understand whether there is a functional relationship between xylem vessel anatomy and vine vigor. Documents Grant with Washington State University. Formerly 5358-21000-034-24G (12/2008). 3.Progress Report We measured the xylem anatomy of green shoot at different thicknesses along the top, middle, and bottom position of the grapevine shoot. Cross sectional areas of stem indicated that the section area increased from bottom to top. Vascular area (xylem), vascular area percentage (vascular area/section area), vessel area/section, vessel no./section, and pith area, all increased from bottom to top; however, pith area showed an opposite trend, i.e. decreased from base to top. Since xylem hydraulic conductivity is proportional to vessel lumen diameter, there will be spatial differences in hydraulic conductivity along the stem. Accordingly, the hydraulic conductance is expected to be greatest at the bottom and lowest at the top of the shoot. Vigorous vines are likely to grow with increased xylem density and vessel lumen size compared to a non-vigorous vine. Morphometric analysis indicated that the shoot length had a positive linear relationship with shoot diameter, node number and leaf area (i.e. different vigor levels). Regression analysis of xylem features according to vigor levels showed that shoot length was positively correlated with stem cross sectional area, vascular area, vessel no./section, vessel no./wedge, and vessel area/section. There was a weak but significant relationship with xylem wedges/section, vessel diameter, and vessel area %. Shoot length was negatively related with pith area %. No significant relationship was detected between shoot length and vascular area % or pith area. Currently, growth characteristics are being measured and analyzed and at the end of season, the impact of vigor levels on fruit maturity and composition will be examined. Methods of ADODR monitoring included meetings, e-mail, and phone calls.