Kansas corn planting progress reached 21% at the state-level as of April 23 (Fig. 1). In many areas of the state farmers are currently making good additional progress planting corn where soils are dry enough. The low temperatures experienced the early morning hours of April 27 have the potential to cause damage on the recently planted corn.
Cold temperatures can result in injury to the germinating seed as it is absorbing moisture. When soil temperatures remain at or below 50 degrees F after planting, the damage to germinating seed can be particularly severe.
Soil temperatures at 7 a.m. on April 27 are presented in Figure 2. The main concern for recently planted corn is for the north central part of the state, where soil temperatures dropped below 40F – reaching a minimum of 37 F at the 2-inch and 45 F at the 4-inch soil depth.
Soil temperatures at the 4-inch depth during the first 72 hours after seeding, when the kernels imbibe water and begin the germination process, are critical. Kernels naturally swell when hydrating. If the cell tissues of the kernel are too cold, they become less elastic and may rupture during the swelling process, resulting in “leaky” cells. Injury symptoms may include swollen kernels that fail to germinate or aborted growth of the radicle and/or coleoptile after germination has begun.
Chilling injury can also occur following germination as the seedlings enter the emergence process, reducing plant metabolism and vigor (Fig. 3).
More information on the effects of freeze injury in corn will be discussed in the next issue of the eUpdate. Stay tuned!
Ignacio Ciampitti, Crop Production and Cropping Systems Specialist
Mary Knapp, Weather Data Library