With air temperatures dropping down into the high teens overnight, I have fielded a number of calls already this morning with the question whether the earlier seeded wheat, barley, oats (or any crop for that matter) will make it, especially if the ground is frozen solid.
The fastest way to tell is to dig up some seed or seedlings and place them on a wetted-down paper towel at room temperature. Within 24 hours you should see elongation of the coleoptile of the seedlings. With seed that had not germinated yet, you may have to wait another day before you see a radicle and coleoptile appear. If the seed and the germ are damaged by frost they will turn to mush within 24 hours at room temperature. If the crop had already emerged, you can simply cut the above ground leaf material and place the seedling on the wetted-down paper towel and wait for new growth to elongate.
PS) Ensure that the paper towel remains moist throughout the duration of the experiment.
Photo 1: Germinated wheat seed with adventitious roots pointing down and coleoptile pointing up. The radicle is hidden between the adventitious roots.