Water Uptake and Drought Tolerance in Great Basin Shrubs

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Sperry 9723464 The goal of the project is to obtain a better understanding of the mechanisms of drought tolerance in plants. The hypothesis is that the ability of a plant to maintain open stomata and survive under drought conditions will correspond to its ability to extract and transport soil water to the foliage. The plant's potential for water extraction is determined by three variables: 1) its susceptibility to xylem cavitation which eliminates plant water transport, 2) its rooting density and distribution, 3) the soil type. Experimental and theoretical analysis of these variables will determine the range of drought stress over which water transport is possible. The "hydraulic potential" of the plant will be compared with its actual water use to evaluate the hypothesis. The research will be conducted on native shrubs of the Great Basin valleys in west-central Utah. These plants experience a relatively wet spring followed by a predictable and usually extreme summer drought. The nine study species represent a spectrum of drought tolerance, differing widely in their seasonal pattern of stomata! opening, vegetative phonology, and rooting distribution.