Record Display for the EPA National Library Catalog
RECORD NUMBER: 15 OF 95
|OLS Field Name||OLS Field Data|
|Main Title||Effects of single and multiple stressors on communities of wheat and wild oats /|
|Author||Pfleeger, Thomas G.|
|CORP Author||Oregon State Univ., Corvallis.;Corvallis Environmental Research Lab., OR.|
|Publisher||U.S. Environmental Protection Agency,|
|Subjects||Wild oat--Effect of stress on. ; Wheat--Effect of stress on.|
|Additional Subjects||Wheat ; Wild oats ; Theses ; Risk assessments ; Ecology ; Ecosystem management ; Natural resources ; Watershed ; Environmental stressors ; Puccinia recondita ; Spring wheat ; Wheat leaf rust|
|Collation||122 leaves, bound : illustrations ; 29 cm|
Most plant toxicology tests developed in support of environmental laws use a single stress applied to an individual plant. While tests using individual species or stresses require fewer resources and are easier to interpret, they are under increasing criticism for being unrealistic and missing important ecological interactions. The objective of this research was to increase our understanding of how plants and plant communities respond to a variety of stressors. Model plant communities of spring wheat (Triticum aestivum) and wild oats (Avena fatua) were planted at three densities and five proportions in the field. Puccinia recondita, the causal agent of wheat leaf rust, was inoculated on half of the plots. Disease severity was estimated as percent of wheat flag leaves covered by rust lesions. Plants were harvested at maturity and measured. Seeding density rarely had a significant influence on rust severity, probably because tiller density differed little as a result of compensation due to increased tillering at low seeding densities. In contrast, increasing the proportion of wheat in mixtures with wild oats consistently increased wheat leaf rust severity. There was no evidence to suggest that wild oats acted as a barrier to inoculum movement. Wild oats' effect on wheat leaf rust was probably through its competitive reduction of wheat tiller density. Both wheat and wild oats seed weight decreased as the proportion of wild oats increased in mixtures.
"June 1998." Includes bibliographical references. Microfiche.