Further investigations into hormone-directed transport in stems.

The effect of IAA and three synthetic auxins on the upward movement of (32)P-orthophosphate and (14)C-sucrose has been investigated in decapitated stems of Phaseolus vulgaris L., Pisum sativum L., Coleus blumci L. and Helianthus annuus L. IAA greatly enhanced the accumulation of (32)P-orthophosphate in Phaseolus vulgaris and Pisum sativum, whereas in C. blumei and H. annuus it did not. 2,4-D like IAA, caused an increase in (14)C-sucrose and (32)P-orthophosphate accumulation in Phaseolus vulgaris but, unlike IAA, caused no increase in Pisum sativum. The downward transport of (14)C-IAA, (14)C-NAA, (14)C-2,4-D and (14)C-2,4,5-T from the decapitated apex was also studied. Results are discussed in terms of current theories of hormone-directed transport.