. The chemistry and mode of action of plant growth substances; proceedings of a symposium held at Wye College, University of London, July 1955. Plant regulators; Auxin; Growth (Plants). Chemical structure and biological activity pure form and its activity similarly demonstrated. This substance is known as Compound F (Steward and Shantz, 1954). It should be mentioned here that a very large number of inactive substances have been fractionated and some of them identified in the coco-nut milk. A variety of amino-acids, including the recently discovered pipecolic acid, were isolated in pure form. N
. The chemistry and mode of action of plant growth substances; proceedings of a symposium held at Wye College, University of London, July 1955. Plant regulators; Auxin; Growth (Plants). Chemical structure and biological activity pure form and its activity similarly demonstrated. This substance is known as Compound F (Steward and Shantz, 1954). It should be mentioned here that a very large number of inactive substances have been fractionated and some of them identified in the coco-nut milk. A variety of amino-acids, including the recently discovered pipecolic acid, were isolated in pure form. None of these functions is the specific response in question. The main new result to be reported is that Compound A has been re- isolated (Shantz and Steward, 1955) and definitely identified as the quite simple but rather unexpected substance, 1:3-diphenylurea. This has been established beyond any doubt by analysis, mixed melting point, completely matching infra-red [Figure 6) and ultra-violet absorption spectra, and all essential criteria for fastidious chemical identification. What is now quite clear is that the response of various strains and varieties of carrot tissue to the. h/ave/ength Figure 6. diphenylurea is very variable. In some cases diphenylurea in presence of casein hydrolysate may replace, in large part, the activity of whole coco-nut milk, approaching at least 50 per cent of that activity. In other cases the activity is small by comparison. The total concentration of diphenylurea that could at its maximum be present in whole coco-nut milk is not large (order of 01 ) and it is quite clear that the coco-nut milk owes its characteristic properties much more to the other substances that are present therein than to the diphenylurea. In fact the paper in which this new discovery has been communicated still makes cautious reservations because the isolation of a relatively small amount of a substance like diphenylurea from a very large amount of biological material
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Keywords: ., bookcentury1900, bookcollectionbiodiver, booksubjectgrowthplants
