California Agriculture
California Agriculture
California Agriculture
University of California
California Agriculture

Larry E. Williams Ph.D.

Professor Plant Physiologist-AES
Kearney Agricultural Research & Extension Center
9240 S. Riverbend Ave.
Parlier, CA 93648
(559) 646-6558 Create VCard

Also in:
Viticulture & Enology


Ph.D., University of Iowa, Iowa City, Iowa, 1978

Research Statement
The major thrust of my research program is currently vineyard irrigation management. I have had irrigation experiments established on wine grapes (trials located in Napa, Monterey, San Luis Obispo and Riverside counties), table grapes (trials located in Fresno and Riverside counties) and raisin grapes (trial located at the Kearney Agricultural Center). The primary objective of these studies is to determine how much water vines will use under non-stressed conditions. The date will be used to determine reliable crop coefficients at the various locations in order to help grape growers schedule irrigations (both timing and amount). Subsequently, I determined the effect of both under- and over-irrigation amounts on vine physiology, growth and fruit yield and quality. I have developed a model to predict water use of Thompson Seedless grapevines and compared the model output with actual water use, measured with a weighing lysimeter. Modeling efforts for both water use and carbon assimilation are proceeding on other cultivars. Lastly, I am currently publishing results from a graduate student who studies water relations of native North American Vitis species grown under soil water deficits. It is anticipated that results from this study may assist grape breeders in developing drought tolerant rootstocks.


Influences of microclimate on physiological processes of the grapevine; cultural techniques of the grapevine associated with the production of raisins and table grapes; carbon assimilation by and allocation in the vine; effect of senescence on gas exchange characteristics; whole plant physiology


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