924 
Journal of Agr icultural Resea rch 
Yol. XXX, No. 10 
‘'intermediate-smooth.” With this 
grouping the distribution of plants in 
F 2 indicates a 2-factor difference for 
roughness of awn between Lion and 
Svanhals. The factor R, when present, 
gives rough awn. The other factor, S, 
is hypostatic to R and in the absence 
of R produces intermediate-smooth 
awn. The double recessive, rrss, is a 
smooth awn of the Lion type. With 
this explanation the ratio in F 2 would 
be 12 rough : 3 intermediate-smooth : 1 
smooth. The observed distribution of 
plants in the F 2 generation grown in 
1922 does not fit the calculated distri¬ 
bution very well, a deviation as large 
as that encountered being expected 
only about 2 times out of 100 trials 
(Table VIII). 
The fit is better for the distribution 
of F 2 plants which were grown in 1923, 
but still the deviation is rather large. 
The reason for these deviations will 
be seen by examining Tables IX, X, 
and XI. 
The behavior of the F 3 lines from 
plants classed in F 2 as rough is in close 
agreement with expectation, X 2 being 
1.4 (P—-0.7097). Of 37 F s lines from 
plants classed in F 2 as intermediate- 
smooth, 7 gave rough-awn plants in 
addition to intermediate-smooths, and 
smooths. However, the discarding of 
these families should not affect the 
expected 1:2 ratio of homozygous to 
heterozygous intermediate - smooths. 
Disregarding these 7 families, the other 
30 families give a close approximation 
of a 1:2 ratio for homozygous interme¬ 
diate-smooth to heterozvgous (see 
Table X). 
Thirtj^-four F 3 lines were grown from 
plants classed as smooth in F 2 . Of 
these lines, 2 gave rough-awn plants, 
intermediate-smooth awn and smooth; 
while 8 gave intermediate-smooth and 
smooth. The other 24 lines vary in 
their indices from 2.85 to 3.61 (see 
Table XI). When a correction is made 
of the F 2 distribution of 1922, on the 
Table VIII.— Distribution of plants for the characters rough awn , intermediate- 
smooth awn, and smooth awn. F 2 generation of the cross Svanhals X Lion. 
1 Character of awn 
Year grown 
| Hough 
Inter- 1 
mediate- 
Smooth 
smooth 
1922_ 
908 
251 i 
100 
948 
237 
79 
1923_ 
362 
79 
39 
360 
| 90 
30 | 
| 
Assumed genotype per 
1 HR SS 
1 rr SS 
1 rr ss 
16. 
;2 Hr SS 
2 HR Ss 
4 Rr Ss 
1 RR ss 
2 rr Ss 
2 Rr ss 
\ 
i i 
: i 
Total 
1, 259 observed. 
1,259+ calculated on 12:3:1 basis. 
X 2 = 8.1. 
P = 0. 0174. 
480 observed. 
480 calculated on 12:3:1 basis*, 
X 2 = 4. 0. 
P = 0. 1353. 
Table mnmary of the behavior of F 3 lines from plants classified in F 2 as 
rough awn; cross SvanhalsX Lion 
: i 
j Number of families 
Behavior of lines 
Breeding true for rough_ 
Segregating rough : intermediate-smooth_ 
Segregating rough : smooth_ 
Segregating rough: intermediate-smooth: smooth 
, | 
: Summary of lines 
P. K. or 
Calcu¬ 
Ob¬ 
segregating 
X 2 
lated 
served 
21.1 
23 
■ 10.6 
1/290 : 71 observed_ 
-|l .- <; 
y 
8 
\270 : 90 calculated_ 
/262 : 81 observed_ 
l\258 : 86 calculated -- 
) ** 
10. 6 
21.2 i 
24 
1/732 : 185:63 observed 
4732 : 183:61 calculated.. 
:;} — 
63. 6 , 
64 j 
Total number families 
