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INDIVIDUAL AND POPULATION RESPONSES TO ABIOTIC STRESSES IN ITALIAN RYEGRASS
MartinezGhersa, M. A., S. R. Radosevich, D M. Olszyk, AND C. M. Ghersa. INDIVIDUAL AND POPULATION RESPONSES TO ABIOTIC STRESSES IN ITALIAN RYEGRASS. Presented at 4th International Weed Science Congress, Durban, South Africa, June 20-24, 2004.
Expected changes in environmental factors will alter productivity of agroecosystems and influence the distribution of agricultural pests. In addition to the natural factors that cause stress, humans introduce chemical pesticides into the agricultural environment. Weeds persist in stress-dominated environments, despite the efforts to eradicate them. This is because plants shift resources between yield and survival. The objective of this research was to assess the impact of three anthropogenic stresses (herbicide, UVB light and ozone) and their interactions on individual Italian ryegrass ontogeny and reproduction. The potential evolutionary effect of these stresses and combinations was also addressed. Individual responses to herbicide were modified by level of tropospheric ozone and UVB light. Plants were capable of growth and reproductive compensation under all stress factors. Compensation occurred at the individual level, modifying growth and carbon allocation to different organs, and at the population level, modifying birth and death rates and density-dependence responses. Interaction of stresses resulted in an increase of relative contribution of smaller individuals in the population to the next generation.
Record Details:Record Type: DOCUMENT (PRESENTATION/ABSTRACT)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LABORATORY
WESTERN ECOLOGY DIVISION
RISK CHARACTERIZATION BRANCH