. Auxins and plant growth. Auxin; Plant growth promoting substances. Extraction and Measurement Techniques 17 the frozen plant material is dried in vacuo without ever experiencing temperatures above freezing. The dry material can then be powdered and extracted with wet 25" C. TEMPERATURE DURING EXTRACTION Fig. 4. The effects of temperature upon auxin yield during extraction of tobacco ovaries witfi wet ether (Wildman and Mnir, 1949). Wildman and Muir have shown that half-hour extractions carried on successively for two hours can effectively extract free indoleacetic acid from lyop
. Auxins and plant growth. Auxin; Plant growth promoting substances. Extraction and Measurement Techniques 17 the frozen plant material is dried in vacuo without ever experiencing temperatures above freezing. The dry material can then be powdered and extracted with wet 25" C. TEMPERATURE DURING EXTRACTION Fig. 4. The effects of temperature upon auxin yield during extraction of tobacco ovaries witfi wet ether (Wildman and Mnir, 1949). Wildman and Muir have shown that half-hour extractions carried on successively for two hours can effectively extract free indoleacetic acid from lyophilized tobacco ovary tissue. The technique may be summarized as follows: 1. Plunge plant material into liquid air or dry ice and acetone for rapid freezing. 2. Dry by lyophilization. 3. Grind to 40 mesh in Wiley mill. 4. Store in vacuo over P2O5, in darkness, until use. 5. Extract with peroxide-free ether (95%) at 0° C for four half- hour intervals. 6. Combine ether extracts and reduce in volume to a few ml. 7. Transfer quantitatively to agar for Avena assay. Some plant materials require neither boiling nor lyophilization for solvent extraction of free auxin. Van Overbeek et al (1945) have established a technique for obtaining free auxin using short term extraction. Free auxin will be obtainable in higher concentrations in the first few ether extractions, whereas enzymatically released auxin will continue to appear over a period of time. These workers have. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Leopold, A. Carl (Aldo Carl), 1919-. Berkeley, University of California Press
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