FACTORS FOE YIELD AND QUALITY OF SPRING WHEAT 15 
The expected ratio for the three awnedness classes on the above 
hypothesis is 1:11: 4. It will be recalled that the distribution of 
the original Moccasin F 2 data was close to this ratio, but that of the 
Bozenian data was nearer a 1:12:3 ratio. Correcting the Boze- 
man F 2 data for the three classes on the Bozeman F 3 results, the 
figures shown in Table 15 are obtained. 
A close fit to the expected ratio for the corrected Bozeman data 
is thus obtained. 
A genetic interpretation of these results can best be made by 
assuming that a primary factor pair (A, a) is responsible for the 
distinction between the awnlessness or short awn development of 
classes 1 and 2 (dominant) as opposed to the longer awn develop- 
ment of class 3 (recessive). Complete dominance is not indicated, 
as it is postulated that it requires the homozygous "dominant" 
(AA) combined with the recessive bb of a secondary pair of factors 
to give complete ehmination of awns (class 1). 
The formula for Hard Federation (1) would be AAbb, Marquis (3) 
aaBB, and the F t AaBb. In the F 2 generation the following formulas 
may represent the breeding behavior of the three classes in F 3 : 
Class 1: 
1 AAbb Awnless; breeding true. 
Class 2: 
4 AaBb Apically awnletted; segregating as F 2 in 1 : 11 : 4 
ratio. 
2 AABb Apically awnletted; segregating for 1 awnless 
to 3 apically awnletted. 
2 AaBB Apically awnletted; segregating for 3 apically 
awnletted to 1 awnletted. 
2 Aabb Apically awnletted; segregating for 1 awnless 
to 2 apically awnletted to 1 awnletted. 
1 AABB Apically awnletted; breeding true. 
11 
Class 3: 
2 aaBb Awnletted; breeding true. 
1 aaBB Awnletted; breeding true. 
1 aabb Awnletted; breeding true. 
4 
The awnletted allelomorph in the primary pair (Aa) of factors 
is represented as recessive in accord with its primary effect. On 
the other hand, it is the awnlessness factor of the second pair (Bb) 
that is represented as recessive in accordance with the one effect 
ascribed to it in this cross. 
Of 145 F 2 families of class 2, one-eleventh, or 13 families, would 
be expected to breed true. It is shown in Table 8 that 17 families 
were of that sort. The segregation of the remaining class 2 groups 
can be determined accurately only by correcting F 3 data on the 
basis of F 4 results, which has not yet been done. 
From the F 3 data, however, which prove classes 1 and 3 are true 
breeding and that the expected portion of class 2 also breeds true, 
it appears probable that the 1:11:4 ratio is the essential explana- 
tion of inheritance of awnedness in the three awnedness classes in 
this cross. The corrected numbers corresponding to this 1:11:4 
ratio from the Bozeman data of 1,050 F 2 plants are 63, 729, and 258 
