POTATO BREEDING AND SELECTION. 35 



ommended in Circular 113 of the Bureau of Plant Industry and 

 Farmers' Bulletin 533, United States Department of Agriculture, 



Every progressive potato grower should have his selection plat, in 

 which to grow his yearly selections; and, in addition, he should have 

 his increase plat, where the promising selections may be increased for 

 the field-crop planting. 



SUMMARY. 



The data presented seem to justify the following statements : 



(1) That the potato crop of the United States is of sufficient economic importance to 

 demand a most careful study of all favorable and unfavorable factors influencing the 

 jdeld . 



(2) That the economic use made of the potato in this country is relatively unim- 

 portant when compared to that of Germany. 



(3) That deterioration of our cultivated varieties through improper cultural practices 

 and through disease necessitates the improvement of existing varieties through the 

 exercise of greater care in the selection of the seed and through the development of new 

 seedUng varieties possessing greater disease resistance or better commercial qualities. 



(4) That the term "plant breeding," when applied to the potato, should be con- 

 strued as sexual rather than asexual reproduction. In other words, it is believed that 

 a distinction should be made between "breeding" and "selection." 



(5) That the work of Goodrich as a potato-plant breeder was epoch making, in that 

 it resulted in gi'ving us the progenitor of the world-famous Early Rose. 



(6) That while the growing of seedling potatoes may offer greater possibilities than 

 selection alone, the latter method can be practiced with much greater ease than the 

 former. Breeding can be indulged in only by the few, while selection may be engaged 

 in by the many. 



(7) That the almost total failure of our present-day commercial varieties to produce 

 seed balls is due to male sterility rather than to imperfect pistils or ovaries. 



(8; That the commonly accepted theory regarding the inadvisabiUty of allowing 

 more than one or two seed balls to develop on a cyme, on the assumption that weak 

 seedlings would result, is not substantiated in crosses 8708, 8709, and 8718, which 

 developed five and six seed balls apiece. 



(9) That the data secured from some of the crosses indicate very strongly that some 

 varieties are prolific seed bearers, while others are not. 



(lOj That the tuber-unit and hill-selection methods of seed selection are chiefly 

 valuable in pointing out the weak, unproductive, and diseased seed tubers. 



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