What Makes Winter Wheat A “Winter Wheat”?

 

For most of us wheat is wheat; however there is a distinct difference between spring and winter wheat, even though the vegetative characteristics of these two wheat types are very similar. Winter wheat can withstand freezing temperatures for extended periods of time during the early vegetative stage and requires exposure to freezing or near freezing temperature to trigger reproductive stage. In other words, if winter wheat does not go through a period of cold temperatures, then it will not produce seed. Two things needed for winter wheat to perform at optimally and produce good yields are- cold acclimation and vernalization.

 

New emerged winter wheat seedlings in early fall are no different than spring wheat seedlings. In order to survive through cold winters with subfreezing temperatures, winter wheat has to be exposed to a series of cooler temperatures early in the growth stage, which is called ‘cold acclimation’ or simply ‘hardening’. The acclimation is possible due to gradual decreases in daily temperatures in the fall after the wheat has emerged. Winter wheat plants adapt to rapidly decreasing temperatures in late fall or winter by lowering moisture content of the ‘crown’ (the growing point at the base of the shoot), decreasing the accumulation of carbohydrates, and slowing down the overall growth process. This greatly helps with frost resistance and other winter conditions that a winter wheat plant has to go through during its life cycle. Cold acclimation generally starts when the temperature starts to fall below 50F.