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New Proposal-2002 |
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TITLE: Does Pollen From Clearfield Winter Wheat Move The Imazamox Resistance Gene to Conventional Wheat and Jointed Goatgrass in Nearby Fields? PERSONNEL: Drs. Philip Westra, Scott Nissen, Claudio Dunan, Pat Byrne, and Scott Haley of Colorado State University; Drs. Dale Shaner and Brian Henry, USDA/ARS TIME LINE: June 1, 2003 through June 30, 2006 HYPOTHESIS: Pollen-mediated gene flow from Clearfield fields to conventional adjacent fields will be negligible. SUMMARY OF PROPOSAL: The introductory year of Clearfield wheat in Colorado represents a unique opportunity to evaluate pollen-mediated gene flow to conventional wheat or jointed goatgrass. We propose to evaluate gene dispersal in 20 conventional wheat fields across Colorado, testing over 6 million wheat seeds. The results of this experiment will provide a solid basis for further evaluation of the potential of Clearfield as an effective and environmentally sound technology. OBJECTIVES: To assess gene flow from Clearfield (Above) winter wheat to conventional wheat and jointed goatgrass across a large landscape. JUSTIFICATION: The level of gene flow at the landscape level is of interest to growers and weed managers as people seek to understand the impact that herbicide resistant crops will have on related crops or weeds. This introductory year (2002-2003) of wide-scale planting of Clearfield (Above) wheat in Colorado affords a unique opportunity to evaluate and understand gene flow from these first commercial Above wheat fields. Although out-crossing in wheat is generally considered to be <1%, some varieties have shown higher rates, prompting a reconsideration of isolation distances for seed production (Hucl and Matus-Cadiz, 2001). Similar work with canola in the introductory year of Clearfield varieties in Australia showed that in 63 sampled fields, 63% of sampled conventional canola fields showed the presence of the Clearfield gene, and the percent resistance in seed samples ranged up to nearly 0.2%. Most conventional canola fields, however, contained less than 0.03% resistant seeds. METHODS: A minimum of 20 commercial wheat fields will be sampled in May - June 2003 to assess gene flow from Clearfield (Above) wheat to conventional wheat varieties and jointed goatgrass. We will collect wheat seed from conventional wheat fields growing near Above wheat fields in four regions of Colorado’s Eastern Plains (preferably 10 feet or less between fields). We will sample fields ranging in size from 50 to 300 acres. We will select fields planted with varieties of similar maturity to Above and with the presence of jointed goat grass. The distance of the conventional wheat fields from the Above fields will factor into the final data analysis. When wheat seed reaches physiological maturity in the conventional wheat fields, we will collect 10 stratified samples totaling at least 100,000 seeds (approximately 8 lbs) from each of three locations in each conventional wheat field. Within each sampling strata (distance from the field edge) the sampling locations will be randomly selected. These three locations will be 1, 30, and 120 ft from the edge of the Above field in the direction of prevalent winds during wheat pollination. We will also take 4 stratified samples of 10,000 JGG seeds at each location. To determine whether the Above resistance gene is present in the seed (conventional wheat progeny), the seeds will be soaked for 12 hours in a 10 micro-molar concentration of imazamox. The seeds will also be treated with a fungicide to preclude seed decay from fungi. The seeds will be germinated in large germination boxes lined with germination paper for 7 days. After 7 days, non-germinated seed will be deemed to be susceptible to imazamox, while seeds that germinate will be assumed to contain the Clearfield gene. Germinated seeds will be planted in potting soil, and the plants from these seeds will be tested with an assay system to confirm ALS resistance. We will also use the same methodology to test certified wheat seed from a state where Clearfield varieties have not been released to establish a base line for ALS resistance in winter wheat. While conventional wheat is being sampled in the 20 fields, any jointed goatgrass encountered will be collected for testing with a technique similar to that used for wheat, although working with jointed goatgrass seed will likely require some modifications. We will run this project for 3 years but are only requesting funding for year 1. LITERATURE CITED: Hucl, P., and M. Matus-Cadiz. 2001. Isolation distances for minimizing out-crossing in spring wheat. Crop Sci. 41:1348-1351. Rieger, M. A., M. Lamond, C. Preston, S. B. Powles, and R. T. Roush. 2002. Pollen-mediated movement of herbicide resistance between commercial canola fields. Science 296:2386-2388. PLANNED TECHNOLOGY TRANSFER: Results of this research will be presented at extension grower meetings, through extension educational publications, and through web based technology transfer, including information for the jointed goatgrass web page. We will develop a full Power Point presentation on the results for use by other educators. Where appropriate, information will be shared at national and regional weed science meetings |
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