30 
BULLETIN 1248, U. S. DEPARTMENT OF AGRICULTURE. 
the average number of tubers to the stem several exceptions are 
noted. In the first group 6-ounce whole tubers produced a greater 
average number of tubers to the stem than did the 5-ounce tubers. 
Two exceptions are found in the second group, one in which the 
3-ounce and 6-ounce halved tubers showed higher figures than the 
2-ounce halved and 5-ounce halved tubers, respectively. In the 
third group, with the exception of the 4-ounce quartered sets, there is 
a progressive increase rather than a decrease. 
At the Greeley (Colo.) Potato Experiment Station in 1916 and 1917 
studies were made of the relation of the weight of the set planted to 
the number of stems and tubers produced and of the average number 
of tubers to the stem produced by the Rural New Yorker No. 2. 
These data (Table 14) show a uniform increase in the average number 
of stems and tubers as the weight of the set increases in each of the 
three groups. As a rule, whole sets of the same weight as halved 
or quartered sets produced a larger number of stems and tubers than 
halved sets, and the halved sets showed the same general relation to 
quartered sets. The data under the heading " Average number of 
tubers per stem " do not show as close a correlation in the decrease of 
tubers per stem as the weight of the set increases. 
Similar studies conducted at Jerome, Idaho, with the Charles 
Downing (Idaho Rural) and Russet Burbank (Netted Gem) varieties 
(Table 14) indicate a uniform rate of progression in the number of 
stems as the weight of the set increases in each of the three classes 
of seed, namely, whole, halved, and quartered. 
Table 14. — Relation of the size of set to the average number of stems and tubers 
per set and of tubers per stem in experiments with potatoes grown under irriga- 
tion at Greeley, Colo., and Jerome, Idaho, in 1916 and 1917. 
Weight 
of set. 
Average number of stems and tubers per set and of tubers per stem. 
Rural New Yorker No. 
2 at Greeley, Colo. 
• 
At Jerome, Idaho. 
Kind of set planted. 
Stems 
per 
set. 
Tubers 
per 
set. 
Tubers 
per 
stem. 
Stems per set. 
Tubers per set. 
Tubers per 
stem. 
Charles 
Down- 
ing. 
Russet 
Bur- 
bank. 
Charles 
Down- 
ing. 
Russet 
Bur- 
bank. 
Charles 
Down- 
ing. 
Russet 
Bur- 
bank. 
VFhole: 
Ounces. 
1 
2 
3 
4 
6 
1 
1! 
2 
" '. 
3 
I 
1 
1.'. 
1.75 
2.55 
3.20 
3.65 
4.45 
5.00 
1.80 
2.25 
2.45 
2. 65 
3. 05 
1.50 
L.60 
1. 85 
1.95 
4.20 
6. HO 
7.15 
7. 95 
9. L0 
10.05 
4.00 
4. 80 
5. 25 
5. 65 
6.30 
3. 30 
3. 65 
3. 90 
4. 15 
2. 40 
2.47 
2.23 
2. 18 
2.04 
2.01 
2 22 
2. 13 
2.14 
2. 13 
2.07 
2.20 
2.28 
2.11 
2.13 
2.45 
3.30 
4.45 
4.70 
5.30 
6.05 
2. 10 
2. <;;> 
2 90 
3. 25 
3.50 
1.90 
L.96 
2.00 
2.15 
3.05 
3.85 
4.30 
4.75 
5.20 
2.15 
2. 70 
2.85 
3.20 
3.40 
1.85 
1.90 
2.15 
■2. 35 
6. 20 
9. 15 
11.35 
LI. 30 
13. 10 
L3.35 
6. 85 
7. 85 
8. 75 
9. 10 
9. 80 
6.40 
6. 50 
5. 80 
6. 86 
5. 55 
6. 55 
7. 95 
9.50 
9. 65 
9.90 
5. 20 
(i. 05 
6.45 
ii. 50 
7.40 
4.65 
i. n 
5. 1 5 
5.40 
2.53 
2.77 
2.55 
2.40 
2.47 
2.21 
3. 26 
2. 96 
3.02 
2.80 
2.80 
3.37 
3. 38 
2.97 
3.43 
2 58 
2-ounce 
2 15 
3-ounce 
2.06 
2. 21 
5-ounce . 
2.03 
(i-ouncc 
1.90 
Salved: 
2-oiiiiCC 
2 42 
:;-ouiH:e 
2.24 
2. 26 
2. 03 
('.-ounce 
2. is 
Quartered: 
i'.-oiince '.„ 
2. 51 
r.-oiince 
2.39 
'i-Mince - 
2. 29 
In tjhe case of the average number of tubers per sot planted, two 
exceptions are noted in the Charles Downing variety in which 
