30 



BULLETIN 195; U. S. DEPARTMENT OF AGRICULTTJKE. 



were remarkably uniform in size and there could, therefore, have 

 been little difference in the size of the seed pieces used. Any varia- 

 tion, therefore, which occurred between the plants of the various 

 tubers which were planted would seem to be due to some inherent 

 tendency in the tuber itself. The remarkable dissimilarity between 

 the growing plants of the individual units of a variety planted con- 

 tiguously in the row was so surprising that some three dozen units 

 were photographed and when these were harvested the tubers were 

 also photographed. It was found that the divergency in yield was 

 just as great as in the size and vigor of the plants. In 1912 five 

 units were planted from both the strong and the weak plants, and 

 it was found in practically every instance that the low-yielding 1911 

 plants gave poor germination, a feeble vine growth, and a still lower 

 yield than in 1912 (PL XV). Table VI gives the data obtained 

 during 1911 and 1912 from 12 strong and weak tuber-unit plants of 

 well-known commercial varieties. 



Table VI. — Potato yields from strong and weak tuber-unit plants in 1911 and 1912. 

 [Weight of tuber yields ia pounds.] 



g 



Variety. 



Strong plants, 

 1911. 



Strong plants, 

 1912. 



Weak plants, 

 1911. 



Weak plants, 

 1912. 



f 



1 



9 



Q 



3 



o 

 Eh 



1 



1 



o 



i 



Ah 







"3 

 



1 



1 

 



"3 

 



4245 



Beauty of Hebron 



4.0 

 2.6 

 3.4 

 3.8 

 4.3 

 3.8 

 2.6 

 2.8 

 3.9 

 4.4 

 1.5 

 3.1 



1.5 

 1.6 

 2.0 

 1.3 

 .3 

 .3 

 2.0 

 1.3 

 1.4 

 1.4 

 2.7 

 1.0 



5.5 

 4.2 

 5.4 

 5.1 

 4.6 

 4.1 

 4.6 

 4.1 

 5.3 

 5.8 

 4.2 

 4.1 



2.9' 



4.4 



3.0 



2.0 



4.8 



1.7 



2.9 



2.1 



3.94 



4.1 



3.9 



2.7 



1.2 

 .8 

 .54 

 .6 

 .9 



2.0 

 .85 

 .4 



1.1 



1.7 

 .64 

 .64 



4.1 



5.2 



3.54 



2.6 



5.7 



3.7 



3.75 



2.5 



5.04 



5.8 



4.54 



3.34 



0.4 

 "".'9 



"i.'s 

 ..... 



0.9 

 .8 



1.1 



1.1 

 .8 



1.0 

 .6 

 .3 

 .5 

 .9 



1.3 

 .1 



1.3 



.8 

 1.1 

 1.1 



.8 

 1.9 



.6 

 1.8 



.5 



.9 

 1.5 



.1 



0.7 

 ...„ 



.14 



'".'25 



"."i2 

 ".'i2 



.04 



1.0 

 .14 

 .25 

 .17 

 .04 

 .38 

 .02 

 .29 

 .03 

 .08 

 .33 



1.7 



4235 



Carman No. 1 



.14 



4972 



Gold Co in 



.65 



4968 

 8686 

 4970 



Green Mountain 



do 



li'ish Cobbler 



.31 

 .04 

 63 



5036 



Keeper 



.02 



6153 

 5460 



McCormick 



Norcross 



.41 



5462 

 6480 



do 



Rural Blush 



.2 

 .37 



6690 









Total 











40.2 

 3.35 



16.8 

 1.4 



57.0 

 4. 75 



38.44 

 3.2 



11.37 

 .95 



49.81 

 4.15 



3.0 

 .25 



9.4 



.78 



12.4 

 1.03 



1.77 

 .15 



2.73 

 .23 



4, .50 





Average 



.38 









Two-year tuber-unit average: 



Strong plants — 3.28 pounds primes; I.IS pounds culls; total, 4.46 pounds. 



Weak plants — 0.20 pound primes; 0.51 pound culls; total, 0.71 pound. 

 Gain in primes in favor of sti-ong plants, 1,540 per cent; total gain in favor of strong plants, 528.2 per cent. 



The average yield of merchantable or prime tubers from the strong 

 plants was 3.35 pounds in 1911, with 1.4 pounds of culls, while the 

 yield from the weak plants was 0.25 and 0.78 pound, respectively. 

 In 1912 the yields were 3.2 pounds of primes and 0.95 pound of culls 

 from, the strong plants and 0.15 and 0.23 pound, respectively, from the 

 weak plants. The average production for 1911 and 1912 was 3.28 

 pounds of primes and 1.18 pounds of culls from the strong plants and 

 0.20 pound of primes and 0.51 pound of culls from the weak plants. 

 These yields represent a gain in primes of over 1,500 per cent in favor of 



I 



