Meinzer F C, Rundel P W, Goldstein G, Sharifi M R
Laboratory of Biomedical and Environmental Sciences, University of California, 90024, Los Angeles, CA, USA.
Hawaiian Sugar Planters' Association, P.O. Box 1057, 96701, Aiea, HI, USA.
Oecologia. 1992 Sep;91(3):305-311. doi: 10.1007/BF00317617.
Carbon isotope composition, photosynthetic gas exchange, and nitrogen content were measured in leaves of three varieties of Metrosideros polymorpha growing in sites presenting a variety of precipitation, temperature and edaphic regimes. The eight populations studied could be divided into two groups on the basis of their mean foliar δC values, one group consisting of three populations with mean δC values ca.-26‰ and another group with δC values ca.-28‰. Less negative δC values appeared to be associated with reduced physiological availability of soil moisture resulting from hypoxic conditions at a poorly drained high elevation bog site and from low precipitation at a welldrained, low elevation leeward site. Gas exchange measurements indicated that foliar δC and intrinsic wateruse efficiency were positively correlated. Maximum photosynthetic rates were nearly constant while maximum stomatal conductance varied substantially in individuals with foliar δC ranging from-29 to-24‰. In contrast with the patterns of δC observed, leaf nitrogen content appeared to be genetically determined and independent of site characteristics. Photosynthetic nitrogenuse efficiency was nearly constant over the range of δC observed, suggesting that a compromise between intrinsic water- and N-use efficiency did not occur. In one population variations in foliar δC and gas exchange with leaf cohort age, caused the ratio of intercellular to atmospheric partial pressure of CO predicted from gas exchange and that calculated from δC to be in close agreement only in the two youngest cohorts of fully expanded leaves. The results indicated that with suitable precautions concerning measurement protocol, foliar δC and gas exchange measurements were reliable indicators of potential resource use efficiency by M. polymorpha along environmental gradients.
在具有不同降水、温度和土壤条件的地点生长的三种多花红千层品种的叶片中，测量了碳同位素组成、光合气体交换和氮含量。根据平均叶δC值，所研究的八个种群可分为两组，一组由三个平均δC值约为-26‰的种群组成，另一组的δC值约为-28‰。δC值不太负似乎与土壤水分生理有效性降低有关，这是由于排水不良的高海拔沼泽地的缺氧条件以及排水良好的低海拔背风处的低降水量所致。气体交换测量表明，叶δC与内在水分利用效率呈正相关。最大光合速率几乎恒定，而最大气孔导度在叶δC范围为-29至-24‰的个体中变化很大。与观察到的δC模式相反，叶片氮含量似乎是由遗传决定的，与地点特征无关。在观察到的δC范围内，光合氮利用效率几乎恒定，这表明内在水分利用效率和氮利用效率之间没有出现折衷。在一个种群中，叶δC和气体交换随叶龄组的变化，导致根据气体交换预测的细胞间与大气CO分压之比与根据δC计算的比值仅在两个最年轻的完全展开叶龄组中密切一致。结果表明，在测量方案方面采取适当的预防措施后，叶δC和气体交换测量是多花红千层沿环境梯度潜在资源利用效率的可靠指标。
