Tuesday, April 19, 2011

Are You Feeling Stressed Today?

Standing outside by our warehouse shipping seed was a cold stressful experience today.  It made me think about the corn already planted and how it will be feeling.

Pioneer has a lot of experience with seed planted into cold stressful conditions.  The picture above is from Quebec in April 2010.  I have witnessed corn covered in snow several times in my career.  It happens regularly and Pioneer actually simulates this condition in their research program.

This chart illustrates the effect of snow and the timing of snow's arrival after planting.  Seed is pre-germed for several hours and then planted under 3 inches of crushed ice.  If the seed has a 24 hour head start, the snow/ice has no negative effect. 

The first few hours in the ground have an impact on seed viability.  Soil temperature is important.  The chart below shows the amount of  4 C water that will enter a seed during the first few hours in the soil.  It is in the first 30 minutes that seed takes on the most water.

This is what imbibitional chilling, a fancy word for "its freaking cold", injury looks like. 

But it takes more than the first 30 minutes to tell the whole story.  Pioneer has done stress emergence research for many years.  The chart below tracks changes in the daytime soil temperatures over 14 days at various locations in 2008.  You can see at most of these sites the soil temps rarely got over 55 F (13 C) during the day.

These are the percent stand scores from the same locations.  The locations with the highest soil temperatures at planting have the best stand establishment scores.  The Flandreau and Morden locations had the poorest stands and they experienced freezing temperatures 8-12 days after planting. 
Hybrid selection also has a large impact.  The blue line represents hybrids with a stress emergence score of 4, the red line represents hybrids with a stress emergence score of 7.  Hybrids with strong stress emergence scores make the difference between having an acceptable stand and having to re-plant after a cold wet spell of weather.  

Here are the stress emergence scores for the top 6 hybrids, by sales volume, that leave our warehouse.  As a group they represent 70% of our sales.

Hybrid Family                       Stress Emergence Score
38M58                                                    6
P9855HR                                  Predicted to be Average    
P9623HR                                  Predicted Above Average
P0125HR                                                6
P0118HR                                  Predicted Above Average
P9910XR                                                 5  
An average score is usually 5, so you can see this group is mostly above average for stress emergence.  The 14 day temperature trend is still the same.  I don't see any problem.  "Game on".



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