The effects of endogenous factors (plant age, section length, and section location) and environmental factors (temperature and mineral nutrition) upon organ regeneration on isolated root sections of Ohondrilla juncea L. were used to develop a standard assay system for the study of the chemical regulation of regeneration. Bud and root formation and its polarity in the presence of a variety of regulators alone and in combinations were observed quantitatively. Bud numbers were increased by auxin (low concentrations), cytokinin, and gibberellin treatments. High concentra� tions of auxin inhibited bud formation and this effect was reversed by antiauxin, cytokinin, or gibberellin. Adenine did not counteract auxin� induced bud inhibition but adenine and N�6�benzyladenine did counteract inhibition induced by the purine antagonist 2,6�diaminopurine. Numbers of regenerated roots were increased by auxin treatment and reduced by cytokinin and gibberellin treatment. On control and auxin� treated sections, bud formation was strongly polar and proximal and cytokinin and gibberellin treatments lessened the polarity. Growth retardants inhibited regeneration. Of a number of synthetic auxins tested, 2,4.dichlorophenoxy. acet.O.methylhydroxamic acid and 4�amino.3,5,6.trichloropicolinic acid were the most effective inhibitors of bud formation.
Organ Regeneration on Excised Roots of Chondrilla Juncea and Its Chemical Regulation
