Water stress effects on guard cell anatomy and the mechanical advantage of the epidermal cells
Abstract Vicia faba plants grown under water deficit were found to have guard cells considerably smaller than those of plants grown under well-watered conditions. Stomala of plants adapted to drought conditions have been observed in past studies to maintain opening at plant water potentials lower than those of plants not so adapted. By employing the geometric interpretation of the mechanical advantage (Wu, Sharpe & Spence, 1985), an anatomical/mechanical basis was found that helps explain how such opening in drought conditions can occur. The geometry and resulting mechanical properties of small stomata, in contrast to larger stomata, give them the capability of opening or maintaining open pores with lower guard cell turgor pressures, relative to the turgor of the surrounding epidermal cells.