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New Proposal-2002 |
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TITLE: Environmental and genetic effects on seed dormancy and after-ripening in jointed goatgrass PERSONNEL: Carol Mallory-Smith, Weed
Scientist, Oregon State University COOPERATORS: Joe Yenish, WSU; Tom Peeper, OK; and Tony White, KS TIMELINE: Initiation date – July 1, 2003; Termination date – June 30, 2005 HYPOTHESIS: Differences in seed dormancy may be genetic in origin and/or influenced by environmental conditions during seed development. Cool temperatures at seed development and warm temperatures during after-ripening (AR) may shorten the dormancy period in jointed goatgrass. SUMMARY OF PROPOSAL: A regional field experiment is proposed to study environmental and genetic influences on seed development and the after-ripening period in jointed goatgrass. OBJECTIVE: To examine the influence of precipitation and temperature during spikelet production on post-harvest seed dormancy and after-ripening. To study the genetic variation in jointed goatgrass seed dormancy. JUSTIFICATION: Jointed goatgrass seed produced in a nursery at Corvallis, Oregon, had more dormancy than jointed goatgrass produced at nurseries in Pendleton, and Moro, Oregon (Fandrich and Mallory-Smith 2003). However, the duration of dormancy and affect of after-ripening conditions on nursery-produced jointed goatgrass seed has not been studied. Cool environmental conditions of the Pacific Northwest during grain development followed by high AR temperatures accelerated dormancy loss in several winter wheat cultivars (Hagemann and Ciha 1987). Characterization of the environmental factors which affect the acquisition and loss of jointed goatgrass seed dormancy during seed development and after-ripening, respectively, will allow for site-specific estimation of seed bank inputs. A region-wide study that covers a wide range of precipitation and temperature zones is proposed. METHODS: Four jointed goatgrass populations, 2 winter and 2 spring, and two winter wheat cultivars will be planted at locations in six environments with different temperatures and precipitation levels during spikelet production. Oregon State University will provide the four jointed goatgrass populations; each study participant will grow two local winter wheat varieties and may consider up to two additional jointed goatgrass populations for evaluation. Replicated, small plots (approximately 8 X 8 feet) will be established at each site for fall and spring planting of the jointed goatgrass populations. Jointed goatgrass spikelets will be hand-harvested from four replicate plots at each location approximately one to two weeks before crop maturity. Plants will be clipped below the inflorescence and shaken inside a paper bag to collect only mature spikelets. Winter wheat will be harvested at crop maturity. Four replicate samples of each jointed goatgrass population and winter wheat will be shipped immediately after harvest to Oregon State University. Post-harvest germination tests will be conducted and sub-samples of the remaining spikelets and seed stored at -20, 10, 20, 30, and 40 C for 12 weeks. Primary seed dormancy will be estimated as the difference between post-harvest and after-ripened germination responses. Specific environmental and phenology data will be collected at each site. The data required are: planting date; heading date; harvest date; mean monthly temperature; and mean monthly precipitation. LITERATURE CITED: Fandrich, L. and C. A. Mallory-Smith. 2003. Germination response of spring and winter jointed goatgrass (Aegilops cylindrica) cohorts. WSWS In press. Hagemann M. G. and A. J. Ciha. 1987. Environment X genotype effects on seed dormancy and after-ripening in wheat. Agron. J. 79:192-196. PLANNED TECHNOLOGY TRANSFER: Results will be presented at grower meetings, through extension publications and on the jointed goatgrass web page. Final results will be presented as a paper at the 2005 Western Society of Weed Science meeting |
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