Ozone Depletion, UV-B Radiation and Vascular Plant Performance in Antarctica

南极洲平流层“臭氧空洞”事件的存在和紫外线b辐射水平的增强为评估紫外线b辐射对植物性能的影响提供了一个独特的机会。有几个理由可以预期，紫外线b辐射对南极维管植物的生长可能是一个重大的、日益重要的限制：近年来，南极洲陆地紫外线b辐射水平已显著增加，并可能继续增加，特别是在南方春季；最近对南极水域海洋浮游植物的研究发现，与臭氧空洞事件有关的紫外线- b辐射水平的增强是浮游植物生产力显著降低的原因；对其他地区维管植物的研究表明，补充紫外线b辐射水平会限制许多植物物种的生长；最近的研究表明，来自其他地区的许多禾草和草本植物的叶子在紫外线b辐射到达叶片内部可能敏感的叶肉组织之前，对紫外线b辐射的屏蔽尤其无效。因此，人们可能会怀疑，作为仅有的两种原产于南极洲的维管植物，南极草（Deschampsia antarctica）和forb Colobanthus quitensis在屏蔽紫外线b辐射方面可能相对无效。令人惊讶的是，显然没有研究解决了紫外线b辐射对南极维管植物的影响。提出的研究试图回答紫外线- b，特别是与臭氧空洞事件相关的紫外线- b辐射是否影响D. antarctica和C. quitensis的光合作用、生长和繁殖性能的问题。这种限制的相对大小将通过使用试验场处理来比较紫外线b辐射与其他潜在限制来评估。选择性过滤器将用于去除自然生长植物的紫外线成分，同时将额外的水或营养物质提供给其他植物。这些实地实验将在西弗吉尼亚州进行更详细的调查，使用补充紫外线b辐射治疗。最近开发的技术，如光纤探针，将用于检查D. antarctica和C. quitensis叶片和生殖结构的紫外/可见光光学特性，并评估这些特性如何响应增强的UV - b辐射水平。这种方法将阐明南极植物对野外紫外线b辐射反应的一些潜在机制。

9317019 Day The presence of well-documented stratospheric "ozone hole" events and enhanced ultraviolet-B radiation levels in Antarctica provide a unique opportunity to assess the effects of ultraviolet-B radiation on plant performance. There are several reasons to expect the ultraviolet-B radiation may be a significant, and increasingly important limitation to the performance of Antarctic vascular plants: Levels of terrestrial ultraviolet-B radiation in Antarctica have increased considerably in recent years, and are likely to continue increasing, particularly in austral spring; Recent research on marine phytoplankton in Antarctic waters has found that enhanced ultraviolet-B radiation levels associated with ozone hole events are responsible for significant reductions in phytoplankton productivity; Research on vascular plants in other regions has shown that supplemental ultraviolet-B radiation levels can limit the performance of many plant species; and Recent investigations have show that the leaves of many grasses and forbs from other regions are particularly ineffective at screening ultraviolet-B radiation before it reaches potentially-sensitive mesophyll tissue in the leaf interior. Thus, one would suspect that the grass Deschampsia antarctica and the forb Colobanthus quitensis, which are the only two vascular plants native to Antarctica, are likely to be relatively ineffective at screening ultraviolet-B radiation. Surprisingly, apparently no research has addressed the impacts of ultraviolet-B radiation on Antarctic vascular plants. The proposed research attempts to answer the question of whether ultraviolet-B, particularly ultraviolet-B radiation associated with ozone hole events, affects photosynthesis, growth, and reproductive performance of D. antarctica and C. quitensis. The relative magnitude of this limitation will be assessed by using experimental field treatments to compare ultraviolet-B radiation to other potential limitations. Selective filte rs will be used to remove UV components from sunlight over naturally-growing plants, while additional water or nutrients will be supplied to other plants. These field experiments will be complemented with more detailed investigations using supplemental ultraviolet-B radiation treatments in West Virginia. Recently developed techniques such as fiber-optic microprobes will be used to examine the UV/visible optical properties of leaves and reproductive structures in D. antarctica and C. quitensis, and assess how these change in response to enhanced ultraviolet-B radiation levels. This approach will elucidate some of the underlying mechanisms responsible for Antarctic plant responses to ultraviolet-B radiation in the field.