In this area the start of May brought overnite temperatures in the low to mid 20's and accordingly low soil temps.  The planters were going fast and furious as it was the 1st of May.  I waited until 3 days later when air and soil temps were much better.  Are the early planted fields showing the imbibational chilling affects described?

excerpt:

"As the table indicates, the percent final stand varied considerably depending on the average soil temperature during the four weeks following planting. In Michigan, an average soil temperature of 56 F produced an acceptable final stand of 90%. However, a soil temperature of 48 F resulted in only 81% of plants emerging, and a soil temperature of 41 F produced only a 61% stand in other northern environments. These data suggest that prolonged soil temperatures below 50 F after planting can have serious consequences for stand establishment. However, the degree of damage will vary with soil type and is generally greater in heavier or poorly drained soils."

Monsanto publication

excerpt:

A phenomenon called “Imbibitional Chilling” occurs when a dry seed imbibes cold (below 40°F) water. Imbibitional chilling can cause everything from reduced growth to abnormal growth to even seedling death. Seeds which have already completed water imbibition to start the germination process before chilling occurs suffer little or no damage. Even if germinating seeds are not damaged by imbibitional chilling, long-term effects may be seen on the plant if cool and wet conditions persist. Cold wet soils favor diseases such as pythium and have the additional stress of reduced oxygen levels.