The effects of D-xyloketose and certain root exudates in extension growth

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Abstract
This investigation has been designed, to examine the possibility that the substance which is exuded from the roots of Sorghum seedlings, and which stimulates the germination of the seeds of Striga hermonthica , may promote extension growth in the roots of a variety of species. The technique used involves observations on fragments 1·5 mm. long excised from the extend­ing zones of roots of peas and maize. The effects on the growth of these segments of certain solutions of the natural exudate and of D-xyloketose, which also stimulates the germination of Striga seeds in very low concentrations, have been examined. It has been found that the exudates and the sugar promote extension growth in the root by stimulating longitudinal and lateral extension. Moreover, it has been shown that as with stimulation of the germination of Striga seeds, the activity of exudate and sugar solutions is destroyed by heat and it decreases during storage of the solutions. The conclusion is drawn that the substance which is released from the roots of Sorghum seedlings is a generalized root extension stimulator which promotes the germination of Striga seeds. The substance may be a carbohydrate or a simple deriva­tive and may bear a close relationship to D-xyloketose.
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