1022 
Journal of Agricultural Research 
Vol. XXVIII, No. 10 
In the description of the various F 2 segregates the length of the awn was 
arbitrarily grouped into five classes as indicated in Table II. Individuals with 
awns from 1 to 3 cm. long when awned only at the tip would ordinarily be classed 
as awnless segregates. Those with awns from 4 to 10 cm. in length when found 
at the tips only might be considered in some cases as intermediate, although the 
awnless condition is more or less dominant in wheat crosses. Segregates with 
awns from 4 to 10 cm. in length resembled the awned vulgare wheat, while indi¬ 
viduals with awns greater than 10 cm. in length could be classed as the emmer 
type of awn. In the first four crosses there is a rough approximation to a 3:1 
ratio of awnless to awned. In the fifth cross, Amby X Kubanka, the percentage 
of awned individuals is relatively low. Amby is a completely awnless wheat 
and the Howards ( 8) have found that a true awnless wheat crossed with an 
individual with long awns results in a 15:1 ratio. In this cross of Amby X Ku¬ 
banka the ratio more closely approximates the 15:1 ratio than it does the 3:1 
ratio. 
In general, segregates of crosses between emmer and vulgare wheats can be 
classified as the emmer type or vulgare type according to the shape of the keel. 
In the F 2 segregation of keel type is apparently dependent on a single Mendelian 
factor in some cases, but the classification is more or less arbitrary and the F 3 
behavior does not indicate a single factor difference for this pair of characters. 
In the crosses involving Alaska it was possible to classify the segregates accord¬ 
ing to color of awn. Even in the so-called awnless segregates the length of the 
awn was sufficient to indicate the color present. The classification of awn color 
is very difficult because climatic conditions in many cases apparently inhibit the 
development of the black color, and even in parental varieties the color may 
appear in some individuals and be absent in others. The classification of certain 
individuals as brown is not definite but simply indicates that they could hardly 
be classed as yellow or black. Although the F 2 segregation does not indicate 
any simple Mendelian segregation, the F 3 generation of Marquis X Alaska does 
indicate a single factor difference. 
Grain texture is one of the characters which is unusually difficult to classify. 
The texture of the grain was determined in most cases from a single head of each 
plant in F 2 and F 3 . Subsequent work during the past winter has shown that 
on a single plant certain heads may bear grain, all of which would rank as hard,, 
while other heads of the same plant would have only soft grain. This character 
is apparently dependent on environmental conditions to such an extent that no 
satisfactory genetic analysis can be made of this character, at least in these 
species hybrids. In most of the crosses described the emmer parent had ex¬ 
tremely hard grain, while the vulgare parent has relatively soft grain. The con¬ 
dition is apparently reversed in the case of Marquis X Alaska, however, because 
the Marquis has comparatively hard grain, while Alaska has a starchy grain due 
apparently to the factor for yellowberry. When the factor for yellowberry in 
Alaska is eliminated Alaska has grain practically as hard as the other species 
in the emmer group. This is indicated by the fact that flinty grains are found 
in certain segregates in F 2 and F 3 . 
The cross Marquis X Alaska was carried to the F 3 , and 1,536 F 3 individuals 
were analyzed. A study of the various F 3 families indicates the true genetic 
nature of the F 2 segregates and permits an accurate classification of the F z 
generation. For most characters 110 F 2 segregates are represented in F 3 , 
although for certain grain characters fewer individuals are available, due to 
partial or complete sterility in F 3 . The F 2 behavior, as indicated by F 3 segre¬ 
gation, is shown in Table III. 
