Weakly cytokinin-active diphenylurea derivatives influence adventitious rooting in M26 Malus pumila microcuttings

Abstract

The cytokinin activity of 8 previously unstudied diphenylurea (DPU) derivatives, differing in either type or position of the substituents of the phenyl rings, was investigated. Cytokinin activity was assessed using the betacyanin (so-called amaranthin) accumulation test and the tomato regeneration test. We also assayed their capacity to enhance adventitious root formation in microcuttings of apple rootstock M26 and in a tomato cotyledon rooting test, while their possible auxin-like activity was tested using the pea stem elongation test. All the compounds showed weak cytokinin activity, and this might be responsible for the enhanced adventitious rooting which is induced by some of the compounds. None of the DPU derivatives showed auxin-like activity.