Diversity, roll the dice!

 ​As the Corn harvest season draws towards a close, once again a corn grower witnesses the variability within and among individual fields.  Differences in soil types, crop history and perhaps even rainfall distribution affected corn hybrids’ grain yield and stalk performance.  Genetic diversity among corn hybrids provide opportunity to adjust with choices among next year’s hybrids although weather for the next season is not easily predicted.
 
Zea mays features tremendous genetic diversity due to its cross-pollination biology and humans involvement of exposing it to multiple environments throughout its relatively short history.  The large number of genes on only 10 chromosomes allows fairly rapid expression of mutations.  Hybrids with deeper roots allow water absorption in sandy soils while those with more branching of roots near the surface are better adapted to soils with lots of organic matter from the previous year crop.  If next year’s weather tends to be dry, especially during flowering time, the deeper root hybrid may be favored.  If it is wet during that critical time period, the shallow root type may do better in grain yield and stalk quality.  Mid season wind pressure may favor the hybrid with roots with more branching.
 
Previous crop environments may influence need for resistance to some leaf diseases.  Corn breeders attempt to select away from extreme susceptibility to pathogens such as Exserohilum (Helminthosporium) turcicum, cause of northern leaf blight, and Cercospora zeae-maydis, cause of gray leafspot, but genetic variability among pathogens and weather patterns influence the ultimate threat to the crop.  Genetic variability among corn hybrids and within potential pathogens will always present changes in the affect of corn diseases on performance.  We are dependent upon researcher in both genetics of both host and pathogen to monitor these possibilities.
 
We are also dependent upon growers to access all agronomy knowledge, make the most economic and technical decisions in choosing hybrids for each field for next season-and then roll the dice!