穗三毛的适应性表型可塑性：气孔密度、叶面积和生物量对水分供应变化及温度升高的响应。
Adaptive phenotypic plasticity of Pseudoroegneria spicata: response of stomatal density, leaf area and biomass to changes in water supply and increased temperature.
作者信息
Fraser Lauchlan H, Greenall Amber, Carlyle Cameron, Turkington Roy, Friedman Cynthia Ross
机构信息
Department of Natural Resource Sciences, Thompson Rivers University, Kamloops, BC, Canada.
出版信息
Ann Bot. 2009 Mar;103(5):769-75. doi: 10.1093/aob/mcn252. Epub 2008 Dec 15.
BACKGROUND AND AIMS
Changes in rainfall and temperature brought about through climate change may affect plant species distribution and community composition of grasslands. The primary objective of this study was to test how manipulation of water and temperature would influence the plasticity of stomatal density and leaf area of bluebunch wheatgrass, Pseudoroegneria spicata. It was hypothesized that: (1) an increased water supply will increase biomass and leaf area and decrease stomatal density, while a reduced water supply will cause the opposite effect; (2) an increase in temperature will reduce biomass and leaf area and increase stomatal density; and (3) the combinations of water and temperature treatments can be aligned along a stress gradient and that stomatal density will be highest at high stress. Methods The three water supply treatments were (1) ambient, (2) increased approx. 30% more than ambient through weekly watering and (3) decreased approx. 30 % less than ambient by rain shades. The two temperature treatments were (1) ambient and (2) increased approx. 1-3 degrees C by using open-top chambers. At the end of the second experimental growing season, above-ground biomass was harvested, oven-dried and weighed, tillers from bluebunch wheatgrass plants sampled, and the abaxial stomatal density and leaf area of tillers were measured.
KEY RESULTS
The first hypothesis was partially supported--reducing water supply increased stomatal density, but increasing water supply reduced leaf area. The second hypothesis was rejected. Finally, the third hypothesis could not be fully supported--rather than a linear response there appears to be a parabolic stomatal density response to stress.
CONCLUSIONS
Overall, the abaxial stomatal density and leaf area of bluebunch wheatgrass were plastic in their response to water and temperature manipulations. Although bluebunch wheatgrass has the potential to adapt to changing climate, the grass is limited in its ability to respond to a combination of reduced water and increased temperature.
背景与目的
气候变化带来的降雨和温度变化可能会影响草原植物物种分布和群落组成。本研究的主要目的是测试水分和温度的调控如何影响蓝茎冰草（Pseudoroegneria spicata）气孔密度和叶面积的可塑性。研究假设如下：（1）增加水分供应会增加生物量和叶面积，并降低气孔密度，而减少水分供应则会产生相反的效果；（2）温度升高会降低生物量和叶面积，并增加气孔密度；（3）水分和温度处理的组合可以沿着胁迫梯度排列，且气孔密度在高胁迫条件下最高。方法 三种水分供应处理分别为：（1）环境对照，（2）通过每周浇水使水分比环境对照增加约30%，（3）通过遮雨使水分比环境对照减少约30%。两种温度处理分别为：（1）环境对照，（2）使用开顶式生长室使温度升高约1-3摄氏度。在第二个实验生长季结束时，收获地上生物量，烘干并称重，对蓝茎冰草植株的分蘖进行采样，并测量分蘖的下表皮气孔密度和叶面积。
主要结果
第一个假设得到部分支持——减少水分供应增加了气孔密度，但增加水分供应却减小了叶面积。第二个假设被否定。最后，第三个假设也未得到充分支持——气孔密度对应力的响应似乎是抛物线型的，而非线性响应。
结论
总体而言，蓝茎冰草的下表皮气孔密度和叶面积对水分和温度调控的响应具有可塑性。尽管蓝茎冰草有适应气候变化的潜力，但其对水分减少和温度升高组合的响应能力有限。
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