Environmental Control of Stable Isotope Ratios of Carbon in Plant Tissues

稳定的碳同位素比值代表了一种新的可用于评估植物对环境胁迫的综合反应的技术。这些同位素比率提供了产生关于长期条件和适应的时间平均数据的独特优势。这项研究的目的是描绘环境参数，如蒸汽压差，温度，呼吸分数和土壤氮对稳定的碳同位素比率施加控制，并评估不同的适应水分胁迫的策略如何在生理水平上表现出来。影响碳同位素辨别的环境因素将通过一系列受控的实验室实验和实地研究进行调查。将研究两个利用不同的生态生理策略来适应环境胁迫的研究物种。其中之一是杂色油灌木(Larrea Tridentata)，它是美国西南部沙漠中一种占主导地位的常绿灌木。第二个物种是奥伊亚(Metrosideros Polyma)，夏威夷群岛的一种生态范围广泛的林木。将开发一个根据13C值预测水分胁迫反应的模型，并通过对组织进行13C采样进行测试。并将在实验室和田间受控条件下生长的植物的预测参数与测量参数进行比较土壤水分有效性的梯度。本研究收集的信息有望为这一同位素技术的广泛应用提供基础，并提供新的对植物适应环境胁迫的本质的洞察。

Stable carbon isotope ratios represent a newly available technique for assessing integrated plant responses to environmental stress. These isotope ratios offer the unique advantage of yielding time-averaged data about long term conditions and adaptations. The objectives of this study are to delineate the environmental parameters, such as vapor pressure deficit, temperature, respiratory fraction and soil nitrogen which exert control over stable carbon isotope ratios and to assess how different strategies of adaptation to water stress are expressed on a physiological level. Environmental factors which influence carbon isotope discrimination will be investigated in a series of controlled laboratory experiments and field studies. Two study species which utilize contrasting ecophysiologic strategies for adaptation to environmental stress will be studied. One of these is the creosote bush (Larrea tridentata), a dominate evergreen shrub throughout the southwestern deserts of the United States. The second species is the ohia (Metrosideros polymorpha), an ecologically wide ranging forest tree in the Hawaiian Islands. A model will be developed to predict water stress responses from 13C values, and tested by sampling tissues for 13C, and comparing predicted with measured parameters in plants growing under controlled conditions in the laboratory and in the field along a gradient of soil water availability. The information gathered in this study is expected to provide the basis for wide-ranging application of this isotopic technique and provide new insights into the nature of plant adaptation to environmental stress.