Ackerson R C, Krieg D R
Department of Plant and Soil Science, Texas Tech University and Texas Agricultural Experiment Station, Lubbock, Texas 79409.
Plant Physiol. 1977 Dec;60(6):850-3. doi: 10.1104/pp.60.6.850.
Stomata of corn (Zea mays L.) and sorghum (Sorghum bicolor L.) responded to changes in leaf water potential during the vegetative growth phase. During reproductive growth, leaf resistances were minimal and stomata were no longer sensitive to bulk leaf water status even when leaf water potentials approached -27 bars. Stomata of corn, cotton (Gossypium hirsutum L.), and sorghum appear to respond to changes in the humidity deficit between the leaf and air and in this manner, regulated transpirational flux to some degree. Distinct differences in water transport efficiency were observed in the three species. Under nonlimiting soil water conditions, sorghum exhibited the greatest efficiency of water transport while under limiting soil moisture conditions, cotton appeared most efficient. Corn was the least efficient with respect to nonstomatal regulation of water use. Differences in drought tolerance among the three species are partially dependent on stomatal regulation of water loss, but efficiency of the water transport system may be more related to drought adaptation. This is particularly important since stomata of all three species did not respond to bulk leaf water status during a large portion of the growing season.
玉米（Zea mays L.）和高粱（Sorghum bicolor L.）的气孔在营养生长阶段对叶片水势的变化有响应。在生殖生长期间，叶片阻力最小，即使叶片水势接近-27巴，气孔也不再对叶片整体水分状况敏感。玉米、棉花（Gossypium hirsutum L.）和高粱的气孔似乎对叶片与空气之间湿度亏缺的变化有响应，并以此方式在一定程度上调节蒸腾通量。在这三个物种中观察到了水分运输效率的明显差异。在非限制性土壤水分条件下，高粱表现出最高的水分运输效率，而在限制性土壤水分条件下，棉花似乎最有效。就水分利用的非气孔调节而言，玉米效率最低。这三个物种之间耐旱性的差异部分取决于气孔对水分损失的调节，但水分运输系统的效率可能与干旱适应性更相关。这一点尤为重要，因为在生长季节的大部分时间里，这三个物种的气孔都不对叶片整体水分状况作出响应。
