When a sunflower (Helianthus annuus L.) hypocotyl section is placed in a solution of 10 micromolar 1-naphthylacetic acid, the majority of the auxin enters via the cut surfaces. However, it is the minority entering radially which causes the typical growth response. Auxin supplied only to the apical cut surface gives a weak, slower response.
No takes yet. Share an insight, caveat, or question.
Richard D. Firn (1982) studied this question.
Synapse has enriched 5 related papers. Consider them for comparative context: