Abstract
Corn (Zea mays L.) and sorghum (Sorghum vulgare, Pers.) plants were grown in a vermiculite-gravel mixture in controlled environment chambers until they were 40 days old. Water was withheld until they were severely wilted, and they were then rewatered. During drying and after rewatering stomatal resistance was measured with a diffusion porometer each morning, and water saturation deficit and water potential were measured on leaf samples. The average resistance of the lower epidermis of well watered plants was lower for corn than for sorghum. When water stress developed, the stomata began to close at a higher water potential in corn than in sorghum. The stomata of both species began to reopen normally soon after the wilted plants were rewatered, and on the 2nd day the leaf resistances were nearly as low as those of the controls. The average leaf water potential of well watered corn was −4.5 bars; that of sorghum, −6.4 bars. The lowest leaf water potential in stressed corn was −12.8 bars at a water saturation deficit of 45%. The lowest leaf water potential in stressed sorghum was −15.7 bars, but the water saturation deficit was only 29%. At these values the leaves of both species were tightly rolled or folded and some injury was apparent. Thus, although the average leaf resistance of corn is little lower than that of sorghum, corn loses much more of its water before the stomata are fully closed than does sorghum. The smaller reduction in water content of sorghum for a given reduction in leaf water potential is characteristic of drought-resistant species.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- 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]
- Pallas J. E., Michel B. E., Harris D. G. Photosynthesis, Transpiration, Leaf Temperature, and Stomatal Activity of Cotton Plants under Varying Water Potentials. Plant Physiol. 1967 Jan;42(1):76–88. doi: 10.1104/pp.42.1.76. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Richards L. A., Ogata G. Thermocouple for Vapor Pressure Measurement in Biological and Soil Systems at High Humidity. Science. 1958 Oct 31;128(3331):1089–1090. doi: 10.1126/science.128.3331.1089. [DOI] [PubMed] [Google Scholar]
- Wallihan E. F. Modification and Use of an Electric Hygrometer for Estimating Relative Stomatal Apertures. Plant Physiol. 1964 Jan;39(1):86–90. doi: 10.1104/pp.39.1.86. [DOI] [PMC free article] [PubMed] [Google Scholar]
- van Bavel C. H., Nakayama F. S., Ehrler W. L. Measuring Transpiration Resistance of Leaves. Plant Physiol. 1965 May;40(3):535–540. doi: 10.1104/pp.40.3.535. [DOI] [PMC free article] [PubMed] [Google Scholar]