CROSSING 



59 



IMPROVEMENT AND BREEDING OF CORN 



Varieties. Where did all the varieties come 

 from? There are hundreds of varieties. A lit- 

 tle study into the history of any particular variety 

 will generally show that back somewhere a careful 

 grower spent years in selecting and improving 

 the variety. He always had some ideal in mind, 

 and going into his corn field endeavored to find 

 ears representing this ideal. Perhaps he tried to 

 develop a 12-rowed flint instead of an 8-rowed, or 

 desired some different shape of ear or kernel. By 

 careful and patient selection toward his ideal he 

 would finally develop a variety having the desired 

 character. Some man spent 10 to 40 years to 

 fully develop and fix the type. Such a variety is 

 Reid's Yellow Dent. Mr. James Reid began 

 selecting this in 1846, but it was not until 50 

 years later that it came into general cultivation. 



Ear-to-row Breeding. About 1895 general 

 attention was first called to the plan of corn im- 

 provement which we now know as " ear-to-row " 

 breeding. It was found that many ears of corn 

 would yield unusually high, but this could not 

 be told by examining the ear. The new plan 

 was to plant each ear to a row, then in the fall 

 select seed only from those rows giving a high 

 average yield. This method is superior to the 

 old method of merely selecting the best looking 

 ears (Fig. 25). 



Crossing. We have already noted the effect 

 of crossing on corn. New varieties can easily be 

 produced by crossing, and it is sometimes desir- 

 able to cross varieties for this purpose. In fact, 

 many of the variations found in corn fields are 

 due to natural crossing, which is commonly due 

 to the great distance pollen is carried by wind. 



FlG 23 _ Stalk of 



Son 8 ? Ex P eriment Sta ~ 



