The effect of wind gusts on leaf growth and foliar water relations of aspen

Potted plants of various trees and shrubs (clones), exposed in the dividing strip and along the border of a motorway, showed an inhibition of leaf growth and a faster development of necrotic leaf areas, when suffering from water deficiency. In greenhouse experiments with potted aspen exposed to periodic artificial wind gusts, wind velocities of 6 m/s were sufficient to inhibit leaf growth by 50%. Therefore it is suggested that repeated strong shaking of plants grown near a motorway, caused by traffic wind, might be responsible for this inhibition. Measurements of water relations did not show obvious changes when aspen trees with \(1{\raise0.5ex\hbox{$\scriptstyle 1$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 2$}}\)-month old leaves were treated with wind gusts, but when plants were continously treated with wind (6 m/s) significant increases in stomatal diffusive resistances and transpiration rates were found as well as a significant decrease in water potential. Aspens with young leaves, exposed to the same treatment, showed a rising of stomatal diffusive resistance in the beginning, but after about \(1{\raise0.5ex\hbox{$\scriptstyle 1$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 2$}}\) h diffusive resistances suddenly decreased. Subsequently after a 2 to 3-h wind treatment intercostal necrosis appeared over the whole leaf surface.