Abstract
Bean plants (Phaseolus vulgaris L.) infected with the rust Uromyces phaseoli became unusually susceptible to drought as sporulation occurred. Under the conditions used (1,300 ft-c, 27 C, and 55% relative humidity) such plants wilted at soil water potentials greater than −1 bar, whereas healthy plants did not wilt until the soil water potential fell below −3.4 bars. Determinations of leaf water and osmotic potentials showed that an alteration in leaf osmotic potential was not responsible for the wilting of diseased plants. When diffusive resistance was measured as a function of decreasing leaf water content, the resistance of healthy leaves increased to 50 sec cm−1 by the time relative water content decreased to 70%, whereas the resistance of diseased leaves remained less than 8 sec cm−1 down to 50% relative water content. Apparently, water vapor loss through cuticle damaged by the sporulation process, together with the reduction in root to shoot ratio which occurs in diseased plants, upset the water economy of the diseased plant under mild drought conditions.
Full text
PDF
Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Boyer J. S. Differing sensitivity of photosynthesis to low leaf water potentials in corn and soybean. Plant Physiol. 1970 Aug;46(2):236–239. doi: 10.1104/pp.46.2.236. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Boyer J. S. Leaf enlargement and metabolic rates in corn, soybean, and sunflower at various leaf water potentials. Plant Physiol. 1970 Aug;46(2):233–235. doi: 10.1104/pp.46.2.233. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gardner W. R., Ehlig C. F. Physical Aspects of the Internal Water Relations of Plant Leaves. Plant Physiol. 1965 Jul;40(4):705–710. doi: 10.1104/pp.40.4.705. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jarvis P. G., Slatyer R. O. Calibration of Beta gauges for determining leaf water status. Science. 1966 Jul 1;153(3731):78–79. doi: 10.1126/science.153.3731.78. [DOI] [PubMed] [Google Scholar]
- Kanemasu E. T., Tanner C. B. Stomatal diffusion resistance of snap beans. I. Influence of leaf-water potential. Plant Physiol. 1969 Nov;44(11):1547–1552. doi: 10.1104/pp.44.11.1547. [DOI] [PMC free article] [PubMed] [Google Scholar]