The relation between oxygen and water uptake by roots of intact plants /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
[College Station, Tex.] :
Holder,
1978.
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| Subjects: | |
| Online Access: | Link to ProQuest copy Link to OAKTrust copy |
| Abstract: | Bean plants (Phaseolus vulgaris L. var. 'Blue Lake') were grown in small pots, transferred to large root chambers with washed quartz sand and further established until the flowering stage, in a large growth chamber. Maximum irradiance at the level of the established plants averaged 74Wm⁻². Daylength was set for 14 hours with a simulated sunrise and sunset over 2-3 hours each. The plants were tested in a stem chamber attached to the root chamber so that the root and upper plant environments were separately controlled. A continuous flow system was used in both chambers. Oxygen uptake and water uptake measurements were made with a polarographic electrode and differential psychrometer respectively, under varying oxygen concentrations from 0.4-21% and standard transpiration conditions of about 44% relative humidity and average irradiance of 47Wm⁻². A potential of -0.5 bar was maintained on the root chamber. Leaf diffusion conductance was monitored with a diffusive resistance meter. The data showed a direct linear relation between oxygen uptake and water uptake in individual and combined data when expressed on a unit root weight and unit leaf area, respectively. Data was excluded when there was suspected damage to the root tips and where a sudden large increase in oxygen level was introduced after prolonged exposure to low oxygen levels. Bean roots exposed to 1.9 to 1.4% oxygen for longer than 8 but less than 18 hours showed a disruption in water uptake. This was observed as a temporary increase to the maximum water uptake for about 4 hours, followed by a decrease to about 5% of the maximum rate. The ratio of water uptake to oxygen uptake ranged from 179 to 322 on a weight basis. Recovery from long exposure to low oxygen levels was delayed for 1 day and 5 days was not long enough for recovery of the maximum water uptake rates observed before the low oxygen treatment. |
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| Item Description: | "Major subject: Soil Physics." Vita. |
| Physical Description: | x, 75 leaves : illustrations ; 28 cm |
| Bibliography: | Includes bibliographical references (leaves 56-59). |