Phytohormonal levels in spruce roots under aluminium stress

Abstract

Aluminium induces morphological changes of spruce (Picea abies (L.) Karst.) seedling roots. Changes in root length are recorded as parameters sensitive to aluminium stress. The possibility of AI-induced increase of cytokinin-like substances and enhanced ethylene evolution has been established as being dependent on the concentration and period of Al exposure in our previous studies. In the present study, 0.74 and 1.85 mM Al in nutrient solution increased levels of cytokinin-and gibberellin-like substances after 4 months of stress. Predominantly, the increase of the indole-acetic acid content was highly significant (Experiment 1). Higher external Al concentrations, than the above mentioned, or longer periods of exposure, were responsible for inhibition of all phytohormones (Experiment 2). In the Experiment 3,5 h exposure to 5.56 mM Al decreased the level of cytokinin-like substances, 40 h exposure to Al evoked their increase. The levels of gibberellin-like substances were stimulated during both intervals. The increase in indole-acetic acid content was significant after 5 and 40 h. Changes in phytohormonallevels induced by Al are undoubtedly a reason for the typical morphological changes in spruce roots under aluminium stress.