I/O 



Bulletin 251. 



breeding-plot in the second year, weigh up the product of each four-hill 

 tuber-unit in the same way to determine which unit of the second year's 

 selections has transmitted in greatest degree the tendency to yield heavily. 

 Finally, select again the fifty best tuber-units to continue the breeding, 

 and retain the good tubers of discarded units to plant a multiplication- 

 plot in the fourth year. The numbering of the units in this year can be 

 continued according to the same policy. 



In the third year, a multiplication-plot should be planted with the 

 good tubers from the discarded tuber-units of the breeding-plot of the 

 second year. In planting this plot, the grower can use any method of 

 cutting and planting the tubers which he thinks most desirable. This 

 plot should give enough seed to plant a fairly large plot in the fourth 

 year. 



Fourth year's selections. — In the fourth and succeeding years the 

 selection should be carried on by the same plan as outlined above. When 

 this system is well under way, it will be seen that each year the breeder 

 is growing a small breeding-plot, a larger multiplication-plot for seed 

 purposes and a general crop. 



Further considerations. — As the selection progresses many of the 

 strains from the original fifty tuber-units will be entirely discarded, 

 the breeder must be continuously watching for the appearance of heavy 

 yielding strains and if such a strain is discovered all of the further selec- 

 tions should be made from this strain. Such a strain is well illustrated 

 in the selection from heavy yielding hills made by ^^'^ade. The following 

 table showing Wade's results is very interesting : 



Yields (by weight) from Seed Selected from High-Yielding Hills. 



{Variety, Carman No. 3.) 



Yields of groups of lo hills each grown from original hills or from their products. 



HILL No. 



1 . 



2 . 

 3- 

 4- 

 S- 

 6. 



7- 

 8. 



9- 

 10. 



Totals. 



Yield of 



selected hills, 



1903 



Lbs. 



Oz. 

 8.0 



13 



10 



2 



3 



I 



I 



14 



Total for lo- 



hill group, 



1904 



Lbs. 



13 



S 



2 



I 

 2 

 o 

 3 

 o 

 2 



Oz. 



12.0 

 4-5 

 i-S 



iS-o 

 8.S 

 9-5 

 8.5 



II -S 



14. 5 

 0.5 



I2S 



6.0 



Total for 



corresponding 



lo-hill groups, 



1906* 



Lbs. 

 9 

 9 

 10 

 I 

 I 

 4 

 5 

 3 

 I 

 o 



Oz. 



4.8 



o 



14 



I 



10 



3 

 1 1 



4 

 6 



S 



116 



13 -o 



Average 



lo-hill groups, 



1904-5-6 



Lbs. 

 13 

 13 

 13 

 13 

 13 

 13 

 IS 

 14 

 14 

 13 



Oz. 

 1-3 

 4.7 



ii-S 

 9-3 

 9-3 

 4.2 



14.3 

 0.3 



10. 2 

 9.8 



* Average yield of original and duplicate tests. 



