Comstock J P, Ehleringer J R
Biology Department, University of Utah, Salt Lake City 84112.
Proc Natl Acad Sci U S A. 1992 Aug 15;89(16):7747-51. doi: 10.1073/pnas.89.16.7747.
Genetic variation in both carbon isotope discrimination and the proportions of leaf and photosynthetic twig tissues were observed in ecotypes of Hymenoclea salsola T.G., a common shrub in the deserts of the western United States, when grown under common garden conditions. These variations were correlated with climatic conditions in the habitats of origin through a model that described the leaf-to-air water vapor gradients experienced by plants during the growing season. Both carbon isotope discrimination and the proportion of leaves in the canopy were lower in plants derived from habitats with higher leaf-to-air vapor gradients, despite the fact that some of these sites received relatively high amounts of annual precipitation. These patterns were consistent with the notion that plants are able to maintain substantial control of water-use efficiency over large environmental gradients of temperature and moisture availability.
在美国西部沙漠常见的灌木盐生膜果麻黄（Hymenoclea salsola T.G.）的生态型中，当在共同园圃条件下种植时，观察到碳同位素分辨率以及叶片和光合嫩枝组织比例的遗传变异。这些变异通过一个描述植物在生长季节经历的叶 - 气水汽梯度的模型，与原生栖息地的气候条件相关联。尽管其中一些地点年降水量相对较高，但来自叶 - 气水汽梯度较高栖息地的植物，其碳同位素分辨率和冠层中叶片的比例都较低。这些模式与植物能够在温度和水分可利用性的大环境梯度上对水分利用效率保持实质控制的观点一致。
