INBREEDING-the FIRST STEP 
T HE first requisite of a hybrid rorn program is tlie development of pure inbred lines 
• which possess desirable traits. 
INBREEDING A STALK OF CORN 
Inbreeding selected corn ears uncovers varied plant types. Some offsprings turn out 
strong and vigorous and others weak and useless. PIONEER breeders, each year, discard 
thousands of weak plants, saving only desirable types for further development. 
After many years of careful inbreeding, weak and undesirable characteristics become 
weeded out. Only tlie strongest plant varieties survive the rigorous inbreeding period 
which usually lasts from five to eight years. 
The result is a pure inbred, small and frail in appearance, but uniform and true to 
definite characteristics, such as disease resistance, plant height, stiffness of stalk, heaviness 
of root system, size of ear, ear height, and color of leaf. 
An inbred strain remains pure, and lireeds true to its characteristics as long as foreign 
]>o]len does not contaminate it. 
Inbreeding separates weak and strong plants. These plants are descendants of the 
same original ear of open-pollinated corn. Only healthy offspring are saved. 
The Pioneer Hi-Bred Corn Company, first commercial producer of hybrid seed corn. A Pioneef Inbred StrOitt show ing uniformity of plant size and 
has the largest and most valuable collection of inbred strains in the Corn Belt. ear height after six years of rigorous inbreeding. 
