BULLETIN OF THE 



IDWIIMOfAffldTIi 



No. 195 



Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief. 

 May 20, 1915. 



(PROFESSIONAL PAPER.) 



POTATO BREEDING AND SELECTION. 



By William Stuart, 

 Horticulturist, Office of Horticultural and Pomological Investigations. 



CONTENTS. 



Introduction 1 



Potato breeding and selection defined 2 



Limitations of breeding and selection 2 



Early attempts at potato breeding 3 



Technique of potato breeding G 



Pollen-producing varieties 9 



Results of experimental crossing 1 1 



Reciprocal crosses 15 



Varietal aflinity 10 



Potato crosses made in 1910 17 



Method of growing and testing seedlings 18 



Seedling inheritance in the Fi generation 20 



Potato improvement by selection 21 



Early selection experiments 22 



Selection methods 27 



Departmental investigations 29 



Summary 35 



INTRODUCTION. 



The increasing commercial importance of the Irish potato as an 

 article of human diet and its adaptation to widely varying climatic 

 conditions liare served to extend its cultivation throughout most of 

 the agricultural sections of the United States. 



Although the potato crop now ranks sixth in agricultural impor- 

 tance in the United Statos, it has hy no means assumed the position 

 that its wide use as a tahlo food would seem to justify. Our present 

 average annual production of potatoes is only about one-fifth that 

 of Germany. Tliis ^vi(h) variation in ])roduction between Germany 

 and the United States may be partially accounted for by the fact that 

 50 per cent or mcjro of the German crop is used either for stock food 

 or for conversion into starch, alcohol, or other industrial ])y-pro(lucts. 

 The American potato crop, ofi the other liand, has no such outlet foi'its 

 surplus tubers, since less tlian 1 per cent of the crop is use<l for indus- 

 trial purposf's. Moreover, the jXT (;aj)ita consumption of potatoes 

 in CJfrmany is about two and on<!-hulf times jis gn^at as it is in this 

 country. Tliesc two factors account in liirg(> nuuisnn^ for tJu^ very 



79257*— Bull. \W,—\r, 1 / 



