140 EDGAR ANDERSON AND WILLIAM L. BROWN 



ly as they can and still be relatively easy to grow and to harvest. It would 

 seem as if the opposite generally has been done. A deliberate attempt has 

 been made to produce inbreds which look as much as possible like good Corn 

 Belt maize in spite of being inbreds. 



There are, of course, practical necessities in breeding. In this direction the 

 work of corn breeders is a remarkable achievement. Strong attention to lodg- 

 ing resistance, to desirable kernel shapes and sizes, and to resistance to 

 drought and disease has achieved real progress. The inbred-hybrid method 

 has permitted much stronger selection for these necessary characters than 

 was possible with open-pollinated maize. Most Corn Belt dents now plant 

 well, stand well, and harvest well. 



Perhaps partly because of these practical points there has been a conscious 

 and unconscious attempt on the part of many breeders to select for inbreds 

 which are like the Corn Belt ideal in all characters, trivial and practical 

 alike. The corn shows are now out-moded, but corn show ideals still influence 

 corn breeding. For instance, there has been an effort to produce plants with 

 greatly arching leaves, whose margins are uniformly ruffled. Such characters 

 are certainly of a trivial nature and of secondary importance in practical pro- 

 grams. Any potential heterosis closely associated with upright leaves, yellow 

 green leaves, tillering, or blades on the husk leaves has seldom had a chance 

 to get into inbreds where it could be tested on a basis of achievement. It 

 would seem highly probable that, in not basing the selection of inbreds more 

 soundly on performance, we have let much potential heterosis slip through 

 our sieve of selection. 



Heterosis Reserves 



These considerations lead us to believe that there is probably a good deal 

 of useful heterozygosis still ungathered in high yielding open-pollinated 

 varieties. There is also a distinct possibility that still more could be added 

 by going back to the Northern Flints and Southern Dents with the specific 

 object of bringing in maximum heterozygosity. From our experience it is 

 more likely that superior heterosis is to be found among the best flints than 

 among the best dents. On the whole, the Northern Flints have been farthest 

 from the corn breeders' notion of what a good corn plant should look like. 

 Flint-like characteristics (tillering, for example) have been most strongly 

 selected against, both in the open-pollinated varieties and the inbreds derived 

 from them. 



Several of the widely recognized sources of good combining inbreds are 

 open-pollinated varieties with a stronger infusion of Northern Flints than 

 was general in the Corn Belt. This is particularly true of Lancaster Surecrop, 

 the excellence of whose inbreds was early recognized by several breeders in 

 the United States Department of Agriculture. In our opinion, it is probable 

 that the greater proportion of flint germ plasm in Lancaster Surecrop has 



