Influence of cold temperatures during the imbibition phase on soybean and corn germination

Abstract Early planting of soybean [ Glycine max (L.) Merr.] and corn [ Zea mays L.] in the Midwestern United States can optimize yield potential but also increase the risk of chilling injury from low temperatures during the imbibitional water uptake phase of germination. This study investigated how the timing and duration of exposure to cold temperature during the imbibition and early germination phases affect seed germination in soybean and corn. A controlled environment experiment was conducted using split‐plot randomized complete block design. Germinating seeds were exposed to an initial warm temperature duration of 0, 2, 4, 8, or 12 h, before being exposed to a cold temperature duration of 3, 6, 12, or 24 h. The 20 warm/cold exposure duration (ED) treatments were imposed using three warm/cold temperature pairs of 15.5/7.2°C, 12.7/4.4°C, or 10/1.7°C. For soybean, the ED was the sole significant factor affecting viability. While the duration of cold temperature exposure exceeding 12 h statistically reduced soybean germination by 7%, final germination rates remained above 85% for soybean and 93% for corn across all treatments after 10 days. For corn, ED and temperature pairing had no effect on seed germination. These findings suggest that short durations of low temperature during imbibition had minimal effects on germination; even when cold exposure extended beyond 12 h, the impact of cold temperature on normal germination was minimal for both corn and soybeans.