Timing of Cold Stress
- Planting just before a stress event such as a cold rain or snow can cause significant stand loss.
- The corn seed imbibes water needed for germination very rapidly – most water is imbibed within the first 30 minutes after exposure to saturated conditions (Figure 3).
Figure 3. Amount of water uptake by corn seed during the first three hours after submersion in 50°F (10°C) water.
- If this early imbibition occurs at cold temperatures, it could kill the seed or result in abnormal seedlings.
- Growers should not only consider soil temperature at planting, but also the expected temperature when seed begins rapidly soaking up water.
- Seed planted in warmer, dry soils can still be injured if cold, wet conditions occur immediately after planting.
- The chances of establishing a good stand are greatly improved with at least 24 hours of warmer, moist conditions for germination to occur before a cold stress event (Figure 4).
Figure 4. Germination of two hybrids with stress emergence scores of 7 (above average) and 4 (below average) following imbibitional chilling induced by melting ice. Ice was applied immediately after planting (0 hours) or after 24 hours or 48 hours of pre-germination in warm conditions.