Many areas in the arid southwestern United States depend upon ground water for irrigation and municipal water supplies. The high transpiration rates of the extensive phreatophyte tamarisk (Tamarix pentandra Pall.) cause considerable depletion of ground water in this region. Eradication of tamarisk communities would appear to be a useful method for salvaging ground water; however, the vigorous reproduction and growth of tamarisk pose economic problems because of the re-treatment and maintenance work required. Also, the removal of tamarisk thickets may adversely affect wildlife habitat, esthetic values, and the ecosystem in general. The use of antitranspirant compounds on tamarisk was investigated in the laboratory, greenhouse, and field, to determine if transpiration could be reduced significantly without damaging the plant. Athel tree (Tamarix aphylla L.) was subjected to the same analyses as tamarisk to better evaluate treatment effects. Initially, several antitranspirants were tested in greenhouse studies from which the potentially useful compounds were selected for more detailed study. Phenylmercuric acetate was toxic to both species and was not used in further experiments with tamarisk. Daily transpiration rates of tamarisk, measured gravimetrically in a greenhouse, were reduced 28 to 36 percent for 20 days with spray applications of 0.01 M 8-hydroxyquinoline sulfate (8-HQS), and the combination of 150 ppm mono-methyl (MDSA) and 150 ppm mono-glyceryl (GDSA) esters of n-decenylsuccinic acid in Triton X-100 (0.5 percent) solutions. The MDSA-GDSA combination and 8_I-[QS significantly reduced stomatal apertures of tamarisk. Stomatal measurements were not obtained for athel tree, although daily transpiration rates of athel tree were reduced 31 percent for 32 days with the MDSA-GDSA combination. The addition of the filmforming Foli-gard (10 percent) did not enhance treatment effect. Treatment effects on net photosynthesis and respiration of both species were evaluated with an infrared gas analyzer. The net photosynthesis rates of tamarisk were significantly reduced 1 to 3 days by 8-HQS and MDSA-GDSA. Respiration rates, measured in the dark, were increased significantly only by 8-HQS. Net photosynthesis rates of athel tree were significantly reduced 13 days by MDSA-GDSA, but there were no effects on respiration. MDSA-GDSA and 8-HQS reduced tamarisk growth rates for 10 to 20 days following treaLment. These growth reductions may have contributed to the decrease in transpiration rates of treated plants. Analyses of foliage samples obtained from tamarisk after treatment indicated that chlorophyll and protein contents were not affected by 8-HQS or MDSA-GDSA. Similar results were noted for athel tree treated with MDSA-GDSA and MDSA-GDSA-Foli-gard. Transpiration rates of potted tamarisk in the field were reduced significantly for only five days by 8-HQS, MDSA-GDSA, and the reflective compound, kaolinite. Rainfall after the fifth day, and phenological phenomena may have contributed to the comparatively short duration of transpiration reduction. Increased foliage temperatures of 1.5 to 2.5 C were detected with a Barnes infrared thermometer 1 and 3 days after treatment. These were obtained under conditions of intense solar radiation, and high air and soil temperatures. This study indicated that tamarisk transpiration can be reduced substantially without lethal increases in foliage temperatures, but with reductions of growth. Additional studies with these antitranspirants may provide a useful management alternative for tamarisk dominated areas to salvage ground water and yet maintain plant cover for wildlife and other uses.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/190931 |
| Date | January 1970 |
| Creators | Brooks, Kenneth N. |
| Contributors | Thorud, David B., Hull, Herbert M., Thames, John L., Ogden, Phil R., O'Leary, James W., Kuehl, Robert O. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Dissertation-Reproduction (electronic), text |
| 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. |
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