lOIO 
Journal of Agricultural Research voi. xxiv. No. la 
Tabi,^ XII. —Distribution of F2 plants classified according to their reaction to Form XIX 
in relation to length of seed 
Classes by reaction to 
Form XIX. 
Classes for length of seed (in millimeters). 
Total. 
Mean. 
4.8 
s.i 
S -4 
5-7 
6.0 
6.3 
IR.. 
5 
17 
9 
3 
34 
S- 79 ±o -03 
HR. 
I 
3 
5 
21 
18 
I 
49 
S. 74 ±o -03 
3 
7 
18 
50 
30 
2 
no 
S- 69 ±o-°* 
HS. 
I 
6 
18 
15 
40 
S- 7 S±o -'>3 
IS. 
2 
10 
33 
81 
67 
9 
202 
S. 74 ±o.oi 
TablB XIII. —Distribution of Fg plants classified according to their reaction to Form 
XXVII in relation to length of seed 
Classes by reaction to 
Form XXVII. 
Classes for length of seed (in millimeters). 
Total. 
Mean. 
4.8 
5-4 
5-7 
6.0 
6.3 
R. 
2 
IS 
46 
24 
6 
93 
S- 7 S± 0-02 
IR. 
4 
5 
3 
2 
14 
S-n±o.o6 
Hi. 
2 
3 
8 
25 
20 
2 
60 
5 . 72 =fc 0.03 
H2. 
2 
17 
32 
28 
3 
82 
5 - 75 ±o *02 
H3 . . . 
I 
4 
II 
19 
10 
I 
46 
5-63^0.03 
H4. 
I 
3 
17 
60 
52 
2 
135 
5 . 77 ±o.oi 
S. 
4 
5 
15 
13 
I 
38 
5 . 72 dbo .03 
The ranges of variability for seed length are somewhat greater, as 
would be expected, for the reaction groups which contain the largest 
number of families. The differences obtained in the means are not 
sufficiently great to indicate any marked linkage between the factors 
of inheritance which govern seed length and those which govern the 
manner of reaction to the forms of stem rust used in the study. 
SUMMARY 
(1) Kota, which is resistant to stem rust in the field but which has 
weak straw when grown under humid conditions, was crossed with 
Marquis, which is susceptible to stem rust but which possesses other 
desirable economic characters. 
(2) A survey of available biologic forms led to the selection of Form 
XIX, to which Marquis was resistant and Kota moderately susceptible, 
and Form XXVII, from which Kota was immune and to which Marquis 
was resistant. These two forms of stem rust were chosen for the study 
with the hope of finding a greenhouse test which could be used as a means 
of isolating F3 families which would prove as resistant as Kota under field 
conditions. 
(3) Out of a total of 787 Fg plants of the Kota-Marquis cross which 
were grown under field conditions, 666 were of normal type and 121 were 
dwarfs. The results were explained on the basis that one of the parents 
contained a factor for dwarf habit and another factor which prevented 
the production of dwarfs. The other parent apparently lacked both 
factors. 
