G. F. SPRAGUE 



USDA and Iowa State College 



Chapter 26 



Early Testing and Recurrent Selection 



It appears desirable to review the history of corn breeding very briefly in 

 order that early testing and recurrent selection may be placed in their proper 

 perspective. The first breeding method used in corn was undoubtedly mass 

 selection. The fact that the corn ear is large, and that harvesting for a long 

 period of time was essentially a hand operation, provided excellent oppor- 

 tunities for selection to be practiced on ear length, diameter, and kernel char- 

 acteristics. This type of selection undoubtedly was practiced from the be- 

 ginning of the domestication of the corn plant until well into the twentieth 

 century. This type of selection was quite effective in modifying ear and kernel 

 characters even though it provided no opportunity for parentage control. 

 Variation in ear size, etc., due to soil fertility were assumed to be genetic. 



Varietal hybridization was the next breeding procedure tried. The results 

 obtained in some cases were very promising, but no extensive use was made of 

 the method. Varietal hybrids, however, did provide source material from 

 which many of the widely grown varieties were isolated. 



The ear-to-row method of breeding was suggested by C G. Hopkins of the 

 Illinois Station in 1896. This procedure, as the name implies, involved select- 

 ing a group of ears, planting these ear-to-row and obtaining information on 

 performance. In such tests, marked differences in yield were obtained among 

 the ears tested. This method was tried rather extensively, but was finally 

 abandoned when it became apparent the cumulative improvement in yielding 

 ability was not realized. 



The ear-to-row breeding method provided for selection on the basis of the 

 visual characters of the original parent ears and some measure of performance 

 based on the progeny of the selected ears. Opportunities for genetic control 

 were limited, and the original high yielding progenies were hybrids of un- 

 known ancestry which could not be duplicated. The ear-to-row method of 

 breeding was quite effective in modifying chemical composition, plant and 



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