For decades, Pioneer plant breeders have selected within the natural variation expressed by corn genotypes to develop hybrids with strong emergence and vigor characteristics under cool soil conditions. In the late 2000’s, Pioneer introduced a new rating for Pioneer® brand corn products called stress emergence. Stress emergence is a measure of the genetic ability or potential to emerge in the stressful environmental conditions of cold, wet soils or short periods of severe low temperatures, relative to other Pioneer brand products. Ratings of 7 to 9 indicate very good potential to establish normal stands under such conditions; a rating of 5 or 6 indicates average potential to establish normal stands under moderate stress conditions; and ratings of 1 to 4 indicate the product has below-average potential to establish normal stands under stress and should not be used if severe cold conditions are expected immediately after planting. Stress emergence is not a rating for seedling disease susceptibility, early growth, or speed of emergence.
Corteva research scientists are continuing to work to improve early season corn performance through conventional and molecular breeding, as well as through rigorous testing of research and commercial hybrids. By identifying molecular markers and pathways associated with superior cold germination, Corteva researchers are beginning to develop an understanding of the genetic basis of stress emergence. This knowledge should eventually lead to even stronger early-season performance in elite Pioneer brand corn products.
Table 2. Corn seedling symptoms and likely causes.
Figure 1. Imbibitional chilling and cold injury. Note club-shaped coleop-tile and leafing out under-ground.
Figure 2. Corkscrew mesocotyl growth. Can be caused by cold soils, extreme soil temperature fluctuations, or soil crusting.
Figure 3. Fused coleop-tile / bursting on the side caused by cold injury.
Figure 4. Corn seedlings with necrotic tissue resulting from flooding.
Figure 5. Corn seedings showing both brown root tissue and bursting on the side due to cold and flooded soil conditions.
The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. Product performance is variable and depends on many factors such as moisture and heat stress, soil type, management practices and environmental stress as well as disease and pest pressures. Individual results may vary. Pioneer® brand products are provided subject to the terms and conditions of purchase which are part of the labeling and purchase documents.