Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 31, 2011
Publication Date: June 8, 2012
Citation: Skinner, D.Z. 2012. Genetics of winter wheat response to two freezing treatments. Crop Science. 131(3):380-384. Interpretive Summary: Winter wheat plants are exposed to various kinds of freezing episodes as they live through the fall and winter months. This study was conducted to assess the genetic control of the ability of wheat plants to survive freezing stress from a rapid drop in temperature, and from a prolonged period of mild freezing followed by potentially damaging temperatures. In both kinds of stress, additive gene action was highly significant, meaning it should be possible to develop increased levels of tolerance to both kinds of freezing stress through conventional breeding methods. Several plant lines were identified that were exceptionally freezing tolerant, indicating that specific gene combinations can be found that greatly improve freezing tolerance.
Technical Abstract: The inheritance of the ability of winter wheat plants to survive two kinds of freezing stress was investigated in a five-parent diallel cross. Plants were acclimated at +4°C for 5 wks and frozen with or without a –3°C, 16-hour pre-freezing (PF) period prior to freezing to damaging temperatures. The PF treatment resulted in significantly increased survival of plants when frozen to the same test temperatures as the NPF tests. When test temperatures were adjusted such that the overall mean survivals of the populations were the same under the two pre-freezing treatment conditions (-10 to -12°C with NPF; -14.5 to -16.5°C with PF), 276 progeny lines survived the NPF and PF treatments equally well, 40 progeny lines survived the PF treatment more frequently, and 52 progeny lines survived the PF treatment significantly less often. Lines that survived the PF tests as well or better than the NPF tests apparently developed significantly more freezing tolerance during the pre-freezing treatment and tolerated the lower test temperatures of the PF tests, while the 52 lines that survived the PF tests less frequently were unresponsive to the PF treatment. Diallel analysis indicated most variation was due to additive genetic effects, but nonadditive effects were significant in two of the 20 crosses. It may be possible to combine additive and nonadditive effects to develop cultivars that are exceptionally tolerant of freezing episodes with or without an extended pre-freezing period.