CROSSING TWO INBREDS TO PRODUCE A ^’SINGLE CROSS’* 
MAKING AND TESTING EMDIMENTAL HYBRID CROSSES-the second step 
TDIONEER breeders make about 175,000 hand pollinations every year. 
^ When corn breeders cross two pure inbreds, each having different 
characteristics, the offspring, a "two-way” or "single cross,” inherits its par¬ 
ents’ best characteristics, growing stronger and more vigorous than either. 
Out of thousands of "single crosses” produced every year, only a few are 
good enough to use for experimental work on final "four-way crosses.” 
The "four-way” hybrid cross is developed by crossing a pair of "two-way” 
or "single crosses,” each of which possesses unlike characteristics. 
Of the hundreds of final crosses made each year by Pioneer corn breeders, 
only a few prove superior to the present commercial hybrids. 
These few outstanding combinations are then tested, over a number of 
years, for yield, lodging, and maturity, in localities where they are to be sold. 
POLLEN BAGS ON 
TASSELS; GLASSINE 
BAGS OVER EAR-SHOOTS 
THE TWO INBREDS ON EITHER SIDE WERE CROSSED TO 
PRODUCE HYBRID IN THE CENTER 
BREEDERS CROSSING TWO "SINGLE CROSS” HYBRIDS 
