Wednesday, 9 November 2005
15

Distributions of Cold Tolerance in F3 Wheat Populations.

Daniel Skinner and Kimberly Garland-Campbell. USDA-ARS, Washington State University, 209 Johnson Hall, Pullman, WA 99164

The temperatures at which 50% of fully acclimated plants are killed (LT50) were determined as -13.6C, -13.5C, and -9.5C, for cultivars ‘El Tan,' ‘Tiber,' and ‘Oregon Feed Wheat #5 (ORFW),' respectively. Thirty-one F2:3 populations from the cross of El Tan X ORFW (E X O) and 31 from Tiber X ORFW (T X O) were acclimated and tested for ability to survive exposure to -12C soil temperature for one hour. The mean percentage survival for the two crosses were virtually identical. However, the mean survival of the T X O F3 populations was less than the midparent while the mean survival of the E X O F3 populations was greater than the midparent. Density plots of the F3 survival percentages showed a bimodal distribution in both crosses with modes at about 10% survival and at 60-80% survival. The density plot of the composite data showed a trimodal distribution, reflecting differences in the two populations. These density plot results suggest polygenic inheritance of response to freezing with the majority of gene combinations conferring very little (ca. 10%) survival, but a slight propensity in favor of 60-80% survival as opposed to 40-50% survival. These results suggest different sets of genes are responsible for cold tolerance in ‘Tiber' compared to ‘El Tan,' even though the standard LT50 test results in virtually identical scores.

Handout (.pdf format, 1989.0 kb)

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