Potato Breeding 55 



It must not be forgotten that potatoes are now grown 

 in regions where the climate is not entirely congenial 

 to them. This constant action of a somewhat unfavor- 

 able climate will also cause them to degenerate if not 

 counteracted by seed selection. 



Careful experiments have been conducted with pota- 

 toes in which the offspring of different tubers are planted 

 and recorded separately. Many of these progenies seem 

 to degenerate completely, indicating that some degen- 

 erative factor, still unknown, is constantly at work. 

 This deterioration is partially due to disease, without 

 doubt, but some of it also is of a physiological nature. 



The yields of any field or the average yields of any 

 locality or of an entire state are far below what they 

 should be. This is due to two causes : the conditions 

 surrounding the crop have not been the best — perhaps 

 insufficient food supply or water or poor soil; and sec- 

 ondly, the absence of seed selection has produced a poor 

 stand of plants, many of which probably give low yields. 

 By proper attention to fertilization, spraying and seed 

 selection, the yield may often be doubled or trebled. 

 Perhaps we can never expect the high yields to the acre 

 obtained in Europe because of our hot dry climate 

 (see Chapter I). 



If seed selection becomes generally practiced, with 

 its accompanying increase in yields, vast consequences 

 may be looked for. If all of the hills on an acre of pota- 

 toes planted in the ordinary manner weigh one-half a 

 pound, there will be a yield of 78 bushels to the acre. 

 A half-pound hill, however, is very small. One ordinary- 

 sized tuber will weigh more than that. If, by means of 

 breeding, the average yield to a hill is increased to one, 

 two or three pounds, which is not at all impossible, the 



