L'Hirondelle Sylvia J, Binder Wolfgang D
B.C. Ministry of Forests Research Branch, Victoria, Canada.
Photochem Photobiol. 2005 Sep-Oct;81(5):1094-100. doi: 10.1562/2005-01-24-RA-425.
Ground-level UV-B radiation has increased globally due to a thinning stratospheric ozone layer. We estimated the effects of increased UV-B on 10 conifer species grown in chambers in greenhouses with supplemental UV-B. Species were selected from a wide range of geographic locations. Plant material of two ages (germinants, first growing season; seedlings, second season) were exposed to three levels of UV-B from ambient (at Victoria, B.C., Canada) to three times ambient (12 kJ m(-2) d(-1)) for up to four months. Frost hardiness and heat tolerance of shoots were estimated from changes in chlorophyll fluorescence after exposure to test temperatures. There were no significant differences among seed sources from different elevations in their response to temperature stresses. When UV-B increased above the ambient level, three species (interior Douglas-fir, Engelmann spruce, and interior lodgepole pine) increased in frost hardiness and four (grand fir, interior spruce, yellow-cedar, and western redcedar) decreased. Two species (western redcedar and western hemlock) increased in heat tolerance when UV-B increased to the 12 kJ level. The main differences in stress tolerance were between the triple ambient and the other two treatments, not between ambient and double ambient, suggesting that any changes in UV-B would have to be large to elicit physiological changes in conifer seedlings.
由于平流层臭氧层变薄，全球地面紫外线B辐射量增加。我们评估了紫外线B增加对10种针叶树的影响，这些针叶树在温室中用补充紫外线B的培养箱中生长。这些物种选自广泛的地理位置。两种年龄的植物材料（发芽期，第一个生长季节；幼苗期，第二个季节）暴露于从环境水平（在加拿大不列颠哥伦比亚省维多利亚市）到环境水平三倍（12 kJ m(-2) d(-1)）的三个紫外线B水平下，长达四个月。通过暴露于测试温度后叶绿素荧光的变化来估计嫩枝的抗冻性和耐热性。来自不同海拔的种子来源对温度胁迫的反应没有显著差异。当紫外线B增加到高于环境水平时，三种物种（内陆花旗松、恩格尔曼云杉和内陆黑松）的抗冻性增加，四种（大冷杉、内陆云杉、黄桧和西部红雪松）的抗冻性降低。当紫外线B增加到12 kJ水平时，两种物种（西部红雪松和西部铁杉）的耐热性增加。胁迫耐受性的主要差异在于三倍环境水平与其他两种处理之间，而不是环境水平与两倍环境水平之间，这表明紫外线B的任何变化都必须很大才能引起针叶树幼苗的生理变化。
