July 1, 1924 
Inheritance in Kota-Hard Federation Crosses 
31 
The average infection of these F 3 
hybrids was 23 per cent, compared with 
7 per cent for Kota and 84 per cent for 
Hard Federation. The average infec¬ 
tion of Marquis grown in check rows 
in the same experiment was 49 per cent. 
Considerable resistance has been ob¬ 
tained in the selected plants, although 
the average percentage is not as great 
as that of the Kota parent. However, 
it is much greater than that of Mar¬ 
quis. 
Unfortunately the resistant plants 
which were separated so that they 
appeared to segregate in F 2 in a 1:15 
ratio were not found to breed true for 
resistance in the F 3 . A large number 
of the so-called resistant F 2 plants were 
segregation in the F 3 according to 
these groups and classes are given in 
Table XXII. 
The data for the resistant groups 
show that there was a much larger 
proportion of resistant plants at Man- 
dan than at St. Paul. This can be 
attributed to the earlier and more 
severe rust epidemic which occurred 
at St. Paul. At Fargo, N. Dak., 
where a few of the resistant F 2 selec¬ 
tions were grown and where rust was 
much more severe than at St. Paul, 
there did not appear to be any F s 
plants which could be classed as re¬ 
sistant or as having the resistance of 
Kota. No definite data were taken on 
the material at Fargo. At Mandan, 
Table XXII.-— Segregation of 10,042 Fz plants of the Kota-Hard Federation and 
reciprocal crosses grown at St. Paul, Minn., and Mandan, N. Dak., in 1923, 
arranged on the basis of infection of the F 2 resistant and susceptible groups in 1922 
Source, group, and infection class in F 2 (per cent) 
Number 
Number of F 3 plants 
Per cent 
resistant 
of F 2 
families 
Suscep¬ 
tible 
Resistant 
Total 
Resistant: ST ‘ PAUL ’ MINN ’ a 
(1-3) 2. . ..... 
2 
26 
6 
32 
18. & 
(4-6) 5. . .. 
17 
213 
38 
251 
15.1 
(7-9) 8______ 
20 
291 
15 
306 
4.9 
(10-12) 11..... 
48 
665 
72 
737 
9.8- 
(13-15) 14_____ 
49 
705 
37 
742 
5.0 
Total....... 
136 
1,900 
168 
2,068 
8.1 
Resistant: mandan, n. dak. 
(1-3) 2.......... 
10 
158 
84 
242 
34.7 
(4-6) 5..... 
40 
773 
191 
964 
19. S 
(7-9) 8____ 
27 
528 
99 
627 
15.8 
(10-12) 11_____ 
116 
1,987 
1,449 
725 
2,712 
1,842 
26.7 
(13-15) 14.... 
80 
393 
21.3 
Total_ ___ 
273 • 
4,895 
1,492 
6,387 
23.4 
Susceptible: 
(16-20) 18 . . . . ___ 
20 
449 
29 
478 
6.1 
(21-30) 25 ...... 
31 
728 
14 
742 
1.9 
(31-40) 35 ____ 
39 
896 
22 
918 
2.4 
(41-50) 45 _ 
20 
474 
3 
477 
.7 
(51-60) 55______ 
20 
517 
3 
520 
.6 
(61-70) 65___ 
14 
331 
4 
335 
1. % 
(71-80) 75...... 
6 
150 
0 
150 
0 
(81-90) 85 . ... 
2 
35 
0 
35 
0 
Total....... 
152 
3,580 
75 
3,655 
2.1 
Mandan total.... 
425 
8,475 
1,567 
10,042 
15.6- 
° F 3 data at St. Paul were obtained by Olaf S. Aamodt. 
grown at both St. Paul and Mandan in 
F 3 , and not one could be said to be 
homozygous for resistance. All of the 
F 3 material grown. at St. Paul and 
Mandan was examined for resistant 
plants, and the percentage of these 
to the total by F 2 frequency classes 
has been determined. Only resistant 
strains were grown at St. Paul, while at 
Mandan both resistant and susceptible 
strains were grown. The resistant 
group of F 2 plants noted for stem-rust 
infection has been classified into 3 per 
cent classes and the susceptible group 
into 10 per cent classes. The data on 
where only fairly severe infection 
occurred, definite data were taken on 
F 3 of both the resistant and the sus¬ 
ceptible F 2 groups. At St. Paul only 
the resistant group was grown. When 
it is divided into five 3 per cent classes,, 
as shown in Table XXII, there is seen 
to be a general, but not a definite,, 
decrease in the percentage of resistant 
F 3 plants. The decrease is from 18.8 
per cent for the 2 per cent class to 5- 
per cent for the 14 per cent class- 
At Mandan there was no general 
decrease among the five classes of 
the resistant group. The resistant 
