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Science 10 March 1967:
Vol. 155. no. 3767, pp. 1248 - 1254
DOI: 10.1126/science.155.3767.1248
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Articles

Plant Moisture Stress: Evaluation by Pressure Bomb

Richard H. Waring 1 and Brian D. Cleary 1

1 Forest Research Laboratory, Oregon State University, Corvallis

The recently developed technique for determining the water stress of a plant by measuring the pressure necessary to force water back to the cut surface of a severed twig is adaptable to both field and laboratory experiments. We have designed and operated an efficient portable system weighing less than 18 kilograms. Sampling variation within and among Douglas fir trees varies from less than ± I atmosphere under low stress conditions to ± 10 atmospheres under high stress conditions. In the measurement of plants of comparable height and similar exposure, the variation is reduced to a minimum. Values in internal water stress of Douglas fir vary from 3 to more than 40 atmospheres. Both duration and magnitude of stress are important ecologically. Pressure-bomb measurements are used to demonstrate a relation between plant distribution and internal water stress.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Mediterranean climate effects. I. Conifer water use across a Sierra Nevada ecotone.
E. B. Royce and M. G. Barbour (2001)
Am. J. Botany 88, 911-918
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Science. ISSN 0036-8075 (print), 1095-9203 (online)