A STUDY OF FACTORS INFLUENCING THE YIELD OF POTATOES 1217 



rot-producing bacteria and fungi. Appleman (1918) has shown that the 

 transverse cutting of seed tubers permits development in the median and 

 basal eyes which would remain more or less dormant if the tubers were 

 planted whole, due to the exclusive development of the terminal eyes. 

 This would indicate a more economical use of seed than is the case if 

 whole tubers are planted. Aicher (1917) and Welch (1917), in a three- 

 years duplicate experiment on irrigated land in Idaho, compared whole and 

 cut seed as to stand, earliness, and yield. Aicher obtained an earlier 

 growth, a more prolific top growth, a larger total yield, and a smaller 

 marketable yield, from whole than from cut tubers. Welch obtained a 

 better stand from the whole tubers, but one that was not commensurate 

 with the extra amount of seed required. He also obtained a smaller 

 marketable yield from whole than from cut tubers, but he does not agree 

 with Aicher that wholeness has anything to do with earliness. The 

 writer is of the conviction that, so far as the relative merit of whole and of 

 cut seed is concerned, these tests of Aicher and Welch are no true criterion. 

 The much greater rate of planting of whole seed over cut seed invalidates 

 any conclusion that may be drawn relative to differences in yield. Har- 

 wood and Holden (1893) reported an interesting experiment attempted 

 by the Tennessee station to test the comparative yields from whole tubers 

 and from an equal weight of halved tubers from the same lot of seed. 

 This eliminated any possible difference in rate of planting, so far as total 

 weight of seed was concerned, but the fact that the half tubers were 

 planted on twice as much area as the whole tubers vitiated the object of 

 the experiment. Nearly two and a half times as much merchantable 

 yield was obtained from the half tubers as from the whole. These same 

 authors report a more nearly accurate test made by the New York station, 

 in which equal-weight seed pieces of whole and cut types were used. The 

 average total yield per acre was the same from the whole and the cut seed, 

 but the marketable yield per acre from the cut seed was nearly double that 

 from the whole seed. 



Large as compared with small seed pieces 



The question of size of the seed piece in relation to yield has been treated 

 experimentally on the basis of both weight and proportion of tuber. 

 Neither basis can be considered quite separately, and both naturally 

 involve the question of rate of planting, the spacing of the seed remaining 

 constant. The hundreds of experiments recorded for the study of size 

 of seed piece are virtually tests of the most efficient rate of planting, tho 

 the objects of and the conclusions for them have been related to size of 

 piece alone. 



Plumb (1890), comparing the yields from whole tubers, halves, quarters, 

 and single-eye pieces, obtained an increased yield with every increase in size 

 of seed, tho the greatest merchantable yield was obtained with the half 



