2008 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. 3.Progress Report It is well known that vigor differs tremendously among different cultivars of wine grapes, resulting large differences in fruit yield and quality. To minimize such variations, growers and viticulturists use various cultural practices, such as trellising systems, pruning techniques, etc., to tame the vine to a desired vigor level so that the targeted yields with the greatest fruit quality can be achieved. The cultural methods to control vigor are well known; what we are not certain about is how these practices regulate vigor of the vine. What are the mechanisms? An understanding of the mechanisms of vigor control has several practical implications. For instance, it will provide better understanding of water consumption by grapevines and, hence, efficient management of irrigation water. To a great extent, planting density of vines is dictated by the pruning strategies (cane or spur, manual or mechanical, and minimal) adopted in the future. Knowing the level of hydraulic limitation caused by a pruning strategy will aid in planting vines with proper spacing and density for both vigorous and non-vigorous cultivars. Grapevines with large canopy size grown in the arid regions of the Northwest experiencing drought conditions become susceptible to drought stress. If this is true, hydraulic limitations early in the season can be used as means to reduce the vigor of the vine and avoid drought stress. A similar strategy will be applicable to grapes grown on shallow and sandy soils. An important concern of WA grape industry is winter injury. The level of winter injury depends upon the vigor of the vine; however, it is not clear how these two phenomena are related. The results of this study will assist in understanding the relationship between vigor and winter injury. Overall, the outcomes of our combined studies will help fine tune the current vineyard establishment and management practices. We gathered data on xylem anatomy from our preliminary experiment. Xylem anatomical data were collected from the basal part of a cane. The data will be compared with measurements from the tip and middle portion of the cane to understand the dynamics of water flow in the current season’s shoot from the experiments initiated in 2008 season. The plant material to carry out the anatomical work for this proposal will be obtained from the field-grown grapevines (Vitis vinifera L. cv. Merlot). In the spring 2008, we pruned Merlot grapevines to a range of bud numbers, which will provides us vines with different vigor levels. Xylem anatomical data from top, middle, and bottom of the canes will be collected after veraison using various microscopy techniques. Similar measurements will be carried out in canes, trunk, and cordons differing in vigor to understand how vigor is related to xylem anatomy and hydraulic conductance. Our study will provide a mechanistic basis of vigor control by considering the anatomy, physiology and hydraulic conductivity of the vine with different vigor levels. Methods of ADODR monitoring included meetings, e-mail, and phone calls.