DEVELOPMENT OF TUBERS IN THE POTATO. 
23 
IX, particularly in the averages of the data obtained in 1917. The 
variation in tuber production according to variety is there clearly 
shown, the number of tubers per hill ranging from 3.8 in the Rural 
New Yorker to 7.1 in the Charles Downing. The lowest average 
weights per hill were produced by the two early varieties, Triumph 
and Early Ohio, and the highest by the Pearl, which is a late variety. 
Table IX. — Effect of irrigation on the average number and the average weight of the tubers 
of different varieties of potatoes grown at Greeley, Colo., in 1917 and 1918. 
Number of tubers per hill. 
Weight of tubers per hill (grams). 
Year and variety. 
No irri- 
gation. 
First 
irriga- 
tion 
after 
tubers 
had 
begun 
to set. 
Irrigation 
started before 
tubers had 
begun to set. 
Aver- 
age. 
No irri- 
gation. 
First 
irriga- 
tion 
after 
tubers 
had 
begun 
to set. 
Irrigation 
started before 
tubers had 
begun to set. 
Aver- 
Medium 
number 
of irri- 
gations . 
Many 
irriga- 
tions. 
Medium 
number 
of irri- 
gations . 
Many 
irriga- 
tions. 
age. 
Experiments in 1917: 
Triumph 
Early Ohio 
Charles Downing 
Pearl 
4.4 
3.2 
5.1 
5.3 
3.5 
3.6 
4.5 
3.9 
4.2 
7.1 
5.1 
3.2 
4.2 
5.6 
7.8 
.6.3 
9.4 
6.2 
4.3 
6.5 
6.9 
5.9 
6.7 
6.6 
7.7 
4.2 
6.2 
9.0 
5.5 
4.8 
7.1 
6.1 
3.8 
5.1 
6.5 
459.8 
413.0 
446.3 
528.0 
533.5 
425.7 
433.7 
697.2 
712.3 
830.3 
887.8 
759.8 
826.7 
867.0 
1,060.7 
928.3 
1,005.7 
1,036.3 
876.7 
974.3 
991.3 
702.0 
1, 145. 
811.3 
1,137.7 
884.7 
868.3 
926.7 
729.9 
730.6 
773.4 
897.5 
Rural New- 
Yorker.. 
Russet Burbank. 
Peachblow 
763.7 
773.8 
804.7 
Average 
4.2 
4.8 
6.8 
6.6 
462.9 
797.3 
981.9 
925.1 
Experiments in 1918: 
Triumph 
Late Ohio 
Charles Downing 
Pearl 
3.6 
3.3 
5.1 
3.3 
3.4 
3.1 
3.1 
5.0 
3.5 
3.8 
3.1 
3.0 
6.5 
3.3 
4.3 
3.6 
3.6 
6.6 
3.7 
4.0 
3.4 
3.5 
5.8 
3.5 
3.9 
. 269.0 
374.2 
342.9 
399.2 
324.3 
266.3 ' 317.5 
482.2 i 675.9 
420.5 ! 589.7 
490. 3 610. 1 
475.4 : 645.5 
365.1 
654.1 
655.9 
676.3 
652.3 
304.5 
546.6 
502.3 
544.0 
R ural New 
Yorker 
524. 4 
Average 
3. 7 1 3. 7 
4.2 
4.3 
341.9 
426.9 ! 567.7 
600.7 
CHARACTER OF SOIL AS RELATED TO TUBER PRODUCTION. 
In 1918 experiments were conducted for the purpose of determining 
to what extent, if any, tuber production is influenced by the type of 
soil. Two varieties, the Triumph and the Rural New Yorker, were 
used for these studies. The seed for each variety, which was obtained 
from a single source, was divided into three lots. One lot of each 
variety was grown on the farm of Mr. W. M. Wilson, 4 on a very heavy 
clay soil classified as "Billings clay loam (3) ;" a second lot was grown 
on the experiment station farm on a clay-loam soil designated as 
"Fort Collins loam (3) ;" the remaining lot was grown on the farm of 
Mr. W. R. McClellan 4 on a sandy loam known as "Colorado fine 
sandy loam (3)." 
The crops on all plats were grown under practical field conditions, 
the cultivation and irrigation practices following the methods in gen- 
«The writer is indebted to W. M. Wilson and W. R. McClellan for their cooperation in growing the 
experimental crops produced on the heavy clay and fine sandy loam, respectively. 
