Effect of environmental factors on cuticular transpiration resistance.

Measurements of the various diffusive resistances to water vapor transport within the leaves of sunflower plants (Helianthus annuus) growing in a controlled environment chamber, were used to calculate values of cuticular resistance under a range of environmental conditions. Cuticular resistance to water loss was found to be inversely related to the relative humidity of the surrounding air, and it is suggested that such a mechanism would form a useful adaptation to arid conditions, enabling plants to maintain a more favorable internal water balance.