XVI International Botanical Congess

The change of water metabolism in the leaves of plants under the effect of toxicants is explained both by violation of functioning of stoma apparatus and by transpiration of water through cuticula. Now the question about the domination of stoma or cuticula mechanisms of protection of assimilative apparatus of plants under the effect of toxicants is discussing actively. The investigations of water keeping ability of leaves Acer platanoides L. under fumigation of plants by HF (0.02 mg/m3 and 1.0 mg/m3) are carried out. The action of HF is reflected first on the stoma apparatus. Under the weak concentration of HF the conductivity of cuticula was increased in 2 times in comparison with the control. Physiologycal meaning of these changes consists in the influence of weak concentration of HF in the highest degree on the stoma apparatus. The strong concentration of HF changes the state of cuticula (destroys its structure). It is confirmed by the increasing of conductivity of cuticula for water molecules.