Author
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Skinner, Daniel |
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Submitted to: Crop Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/21/2014 Publication Date: 6/6/2014 Citation: Skinner, D.Z. 2014. Time and temperature interactions in freezing tolerance of winter wheat. Crop Science. 54:1-7. DOI: 10.2135/cropsci2013.09.0623. Interpretive Summary: Winter wheat plants are planted in the fall, and harvested the following summer. Therefore, in order to survive the temperature fluctuations that occur during the winter months, the plants must tolerate episodes of freezing to various temperatures for various lengths of time. In this study, the ability of six wheat cultivars to survive exposure to a range of subzero temperatures for various lengths of time was studied. As expected, initially, as the length of time plants were exposed to subzero temperatures increased, survival decreased. Surprisingly, however, as the length of time the plants were exposed to subzero temperatures was increased even more, the level of survival significantly increased. Ultimately, survival at the shortest, and the longest, length of time at subzero temperatures studied were not significantly different. These results suggested that certain freezing tolerance mechanism(s) in wheat are activated only after sufficient exposure to subfreezing temperatures for a sufficient amount of time. Lesser exposure to either temperature or time apparently does not activate this mechanism, leading to greater plant death. Further characterization of this mechanism and its genetic control may lead to development of wheat lines with enhanced ability to survive harsh freezing environments and improved winterhardiness. Technical Abstract: In order to survive the temperature fluctuations that occur during the winter months, winter wheat (Triticum aestivum L.) plants must tolerate episodes of freezing to various temperatures for various lengths of time. In this study, the ability of six wheat cultivars to survive exposure to -13.5 to -16.5° C for 2, 3, or 4 hours was measured; tolerance was described as the percentages of plants surviving after time intervals at -10° C or less. The average survival of the six cultivars significantly decreased by about 50% as length of exposure to -10°C or less was increased from 325 to 525 minutes. Surprisingly, survival then increased as exposure time was increased such that survival after 675 minutes was not significantly different from survival at 325 minutes. The greater survival after longer exposure times to -10° C or less, compared to shorter exposure times, suggested that certain freezing tolerance mechanism(s) in wheat are activated only after sufficient exposure to subfreezing temperatures for a sufficient amount of time. Lesser exposure to either temperature or time apparently does not activate this mechanism, leading to greater plant death. Further characterization of this mechanism and its genetic control may lead to development of wheat lines with enhanced ability to survive harsh freezing environments and improved winterhardiness. |
