Effect of Chemical Closure of Stomata on Transpiration in Varied Soil and Atmospheric Environments

Abstract

The effect of phenylmercuric acetate (PMA) spray (90 [mu][image]) on transpiration and growth was studied on tobacco growing in the greenhouse and on sunflowers growing outdoors. In tobacco, which was kept at 2 soil moisture regimes (wet and dry), the reduction of transpiration was initially high (31% on the 1st day after spraying), but diminished to 10% after 11 days as new leaves unfolded and expanded. The effect of PMA in reducing transpiration was about the same in the wet and the dry treatments. No adverse effect that could be attributed to PMA was observed. In the sunflowers, transpiration over 35 days was reduced by 14%; some leaf damage was evident.