EFFECT OF CHANGING THE ENDOGENOUS CONCENTRATION OF AUXINS AND CYTOKININS AND THE PRODUCTION OF ETHYLENE IN PEA STEM CUTTINGS ON ADVENTITIOUS ROOT-FORMATION

Decapitation or treatment with naphthylphthalamic acid (NPA) - an inhi bitor of IAA transport - or a synthetic cytokinin N-(2-chloro-4-pyridy l)-N-phenylurea (CPPU) caused a decrease in rooting of pea cuttings. H owever the mode of action of the above treatments was different. Decap itation resulted in a decrease of indole-3-acetic acid (IAA) and a sim ultaneous increase in cytokinin content at the base of the cuttings. N PA decreased IAA even more, but did not influence cytokinins. CPPU alo ne or in combination with amino-ethoxy-vinylglycine (AVG) - an ethylen e biosynthesis inhibitor - increased IAA at the rooting zone, but CPPU was transported from apex to the base of the cuttings where it inhibi ted rooting. NAA, applied alone after decapitation, stimulated rooting , probably partly by being an auxin, and partly by inhibiting the accu mulation of cytokinins at the base of the cuttings. Treatment with AVG neither influenced rooting nor auxin or cytokinin content. Therefore, ethylene production does not seem to be one of the main factors invol ved in the reduced rooting after the various treatments.