Hauer Richard J, Wei Hongxu, Koeser Andrew K, Dawson Jeffrey O
College of Natural Resources, University of Wisconsin-Stevens Point, Stevens Point, WI 54481, USA.
Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
Plants (Basel). 2021 Apr 10;10(4):742. doi: 10.3390/plants10040742.
Responses to water stress were measured for sugar maple ( subsp. Marshall) sources from Oklahoma (Caddo sugar maple), Missouri, Tennessee, Ontario, and a black maple ( subsp. F. Michx.) source from Iowa. Seedling sources were selected for differences in temperature and precipitation of their geographic origins. Seedlings were preconditioned through moist (watered daily) or dry (watered every 4-7 days) cycles and then exposed to prolonged water stress. As water stress increased, dry preconditioned 17-week-old sugar maple seedlings from Oklahoma, Missouri, and Tennessee, sources from warmer, and/or drier climates with greater restrained photosynthesis, stomatal conductance, and water use efficiency than those from cooler and moister climates. Under imposed water stress, the Ontario and Iowa sourced seedlings increased their root to shoot ratios and decreased their specific leaf area, mechanisms for drought avoidance. However, no corresponding changes in these values occurred for Oklahoma, Missouri, and Tennessee sources and for the variable of leaf wilting across all sources. Results from this study suggest greater tolerance of water stress in the Oklahoma, Missouri, and Tennessee ecotypes from the western and southern range of sugar maple resulted primarily with water use efficiency (WUE) rather than other water stress coping mechanisms. Findings from this study provide evidence to support selection of sugar maples sources for forestation.
对来自俄克拉荷马州（卡多糖枫）、密苏里州、田纳西州、安大略省的糖枫（亚种马歇尔）以及来自爱荷华州的黑枫（亚种F. 米克斯）的水源进行了水分胁迫响应测量。根据幼苗来源地温度和降水量的差异选择了幼苗。幼苗先经过湿润（每日浇水）或干燥（每4 - 7天浇水一次）周期预处理，然后再经受长时间的水分胁迫。随着水分胁迫加剧，来自俄克拉荷马州、密苏里州和田纳西州的经过干燥预处理的17周龄糖枫幼苗，这些来自温暖和/或干燥气候的幼苗，其光合作用、气孔导度和水分利用效率比来自凉爽和湿润气候的幼苗受到更大抑制。在施加水分胁迫的情况下，安大略省和爱荷华州来源的幼苗增加了根冠比并减小了比叶面积，这是避旱机制。然而，俄克拉荷马州、密苏里州和田纳西州来源的幼苗以及所有来源的叶片萎蔫变量在这些值上没有相应变化。本研究结果表明，糖枫西部和南部范围内的俄克拉荷马州、密苏里州和田纳西州生态型对水分胁迫具有更高的耐受性，这主要源于水分利用效率（WUE）而非其他水分胁迫应对机制。本研究结果为支持选择糖枫来源进行造林提供了证据。
