MSU-ERDA Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.
Plant Physiol. 1978 Jun;61(6):1000-5. doi: 10.1104/pp.61.6.1000.
The rates of transpiration from the upper and lower surfaces of leaves of Gossypium hirsutum, Xanthium strumarium, and Zea mays were compared with the rates at which helium diffused across those leaves. There was no evidence for effects of CO(2) concentration or rate of evaporation on the resistance to water loss from the evaporating surface ("resistance of the mesophyll wall to transpiration") and no evidence for any significant wall resistance in turgid tissues. The possible existence of a wall resistance was also tested in leaves of Commelina communis and Tulipa gesneriana whose epidermis could be easily peeled. Only when an epidermis was removed from a leaf, evaporation from the mesophyll tissue declined. We conclude that under conditions relevant to studies of stomatal behavior, the water vapor pressure at the sites of evaporation is equal to the saturation vapor pressure.
对棉花、苍耳和玉米叶片的上下表面的蒸腾速率与氦气穿过这些叶片的扩散速率进行了比较。没有证据表明 CO(2)浓度或蒸发速率对从蒸发表面（“质膜壁对蒸腾的阻力”）损失水分的阻力有影响，也没有证据表明在膨胀组织中有任何显著的细胞壁阻力。在 Commelina communis 和 Tulipa gesneriana 的叶片中也测试了细胞壁阻力的可能存在性，这些叶片的表皮很容易被剥去。只有当从叶片上去除表皮时，质膜组织的蒸发才会下降。我们的结论是，在与气孔行为研究相关的条件下，蒸发部位的水蒸气压等于饱和蒸气压。
