Four new lines in the cooperative Iowa corn breeding program are available for the production of several new hybrids in 1951. The lines themselves won't be released this year. They'll be released in single-cross combintions. The release procedure to be used is similar to that of the other north-central states and is called "delayed release."
Sprague, G. F. and Miller, Philip A.
"New Corn Hybrids for Iowa,"
Iowa Farm Science: Vol. 5
, Article 4.
Available at: https://lib.dr.iastate.edu/farmscience/vol5/iss9/4