- Author: Brooke Jacobs
In the early 1990’s UC Davis Professor Ken Shackel initiated a new research program focused on developing a plant based tool for measuring plant water stress and scheduling irrigation. Dr. Shackel was interested in using a pressure chamber to measure stem water potential, characterize plant water status, and time irrigation throughout the growing season. Pressure chambers had been used for years prior to this research to characterize plant water status and water stress. However, there were no tree crop reference water potential values available that could be used to guide irrigation scheduling decisions. Beginning in the early 1990’s
The Fruit and Nut Research and Information Center collaborated with Dr. Shackel and Charlie Turner (Academic Technology Services, UC Davis) to create a new “Irrigation Scheduling Using Stem Water Potential Measurements” website. Our new website calculates reference water potential for almond, walnut, prune, and grape crops using weather data obtained from nearby CIMIS weather stations and reference water potential models (Shackel et al 1997 and 2000). The home page includes an interactive google map enabling users to select the closest CIMIS station, or the station in the most similar microclimate. We also include pages with background information on tree water use physiology, and a chart outlining the physical symptoms associated with a range of stem water potential measurements in prune, almond, and walnut.
McCutchan, H. and K.A. Shackel. 1992. Stem water potential as a sensitive indicator of water stress in prune trees (Prunus domestica L. cv. French). J. Amer. Soc. Hort. Sci. 117:607–611
Shackel, K.A., H. Ahmadi,W. Biasi, R. Buchner, D. Goldhamer, S. Gurusinghe, J. Hasey, D. Kester, B. Krueger, B. Lampinen, G. McGourty, W. Micke, E. Mitcham, B. Olson, K. Pelletrau, H. Philips, D. Ramos, L. Schwankl, S. Sibbett, R. Snyder, S. Southwick, M. Stevenson, M. Thorpe, S. Weinbaum, and J. Yeager. 1997. Plant water status as an index of irrigation need in deciduous fruit trees. HortTechnology 7:23–29.
Shackel, K., B. Lampinen, S. Sibbett, and W. Olson. 2000. The relation of midday stem water potential to the growth and physiology of fruit trees under water limited conditions. Acta Hort. 537:425–430.
Fulton, A., R. Buchner, B. Olson, L. Schwankl, C. Giles, N. Bertagnia, J. Walton, and K. Shackel. 2001. Rapid equilibration of leaf and stem water potential under field conditions in almonds, walnuts and prunes. HortTechnology 11:609–615.