COMPARATIVE INVESTIGATION OF AUXIN AND FUSICOCCIN-INDUCED GROWTH AND H-EXTRUSION IN COLEOPTILE SEGMENTS OF ZEA-MAYS L()

The effects of IAA and FC on elongation growth of maize coleoptile seg ments and changes of pH of the incubation medium were simultaneously s tudied. In order to evaluate the contribution of the coleoptile lumen to the total H+-efflux appropriate apparatus was designed. The access of IAA or FC to the lumen of coleoptile segments significantly enhance d both H+-extrusion and elongation growth. It has been found that cole optile segments with intact or partly removed cuticle (by abrasion) be haved in different ways both in the presence and the absence of IAA or FC in the medium. Our data corraborate the view according to which ac id growth constitutes a substantial part of the auxin-induced growth.