W502: UV-B Monitoring and Research Program
Statement of Issues and Justification
The USDA UV-B Monitoring and Research Program is a program that was initiated in 1992, through a grant to Colorado State University, to provide information to the agricultural community on the geographical distribution and temporal trends of UV-B (ultraviolet-B) radiation in the United States. This information is critical to the assessment of the potential impacts of increasing ultraviolet radiation levels on agricultural crops and forests.The effects of UV-B enhancements on plants include reduction in yield and quality, alteration in species competition, decrease in photosynthetic activity, susceptibility to disease, and changes in plant structure and pigmentation. This issue is complicated further by reports of equally large response differences among cultivars of a species. About two-thirds of more than 300 species and cultivars tested appear to be susceptible to damages from increased UV-B radiation. In cooperation with universities and government research agencies, research activities on UV-B effects on agricultural crops and ecosystems are carried out through extensive experiments.
The effects of UV-B radiation on plants get much more complicated and convoluted when the enhancement of UV-B radiation is accomponied with other changing abiotic and biotic factors such as high temperature and water stress as predicted in global warming. Recent studies show significant crossing effects of UV-B radition, water stress, high temperature, and CO2 concentration on soybean, cotton, rice, and cowpea. Therefore, all effects of elevated UV-B on plants should be considered in the context of other factors such as water stress, increased atmospheric CO2, tropospheric air pollution, and temperature. While the effects of one factor or few more factors can be examined with the resort to controlled growth chamber, computer modeling has to be exploited to carry out comprehensive studies of interacted effects of multiple factors. Coupling crop growth models with climate models is an efficient and feasible way to assess the potential integrated impacts of enhanced UV-B levels, high temperature, water stress, and CO2 under the context of global warming. Remote sensing techniques and data are particularly useful to extend these studies to a regional or global scale.
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