Eight-day-old mung bean seedlings (Vigna radiata L.) grown in hydropondic medium were osmotically stressed by exposing roots to increasing concentrations of NaCl up to 4 bars. They were transferred after 16 to 18 hours to a similar solution containing tritiated water (THO). Periodic samples were taken of water transpiring from the leaves and of tissue water obtained from the same leaves, frozen and ground; specific radioactivity was determined by a scintillation counter. Proportional to increasing stress, the labelling of tissue water was increasingly delayed, the time for equilibration of the specific radioactivity in the two fractions lengthened, and equilibration occurred at higher concentrations of THO. Thus stress causes transpirational water to be increasingly restricted to extra-cellular pathways. Further investigations of stomatal function by leaf surface, of anatomy and of growth patterns were unsuccessful in finding an explanation for this behavior but did reveal a transpirational circadian rhythm and a continual layer of (air?) space between the palisade and spongy mesophyll, the latter organized into two compact rows.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/278118 |
| Date | January 1992 |
| Creators | Parker, Beverly Jean, 1944- |
| Contributors | Matsuda, Kaoru |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Thesis-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
Page generated in 0.2432 seconds