1028 
Journal of Agricultural Research 
Vol. XXVIII, No. 10 
THE RELATION OF CHROMOSOME NUMBER TO MORPHOLOGICAL 
CHARACTERS IN F 3 AND F 4 SEGREGATES 
It has been found that the segregates of emmer X vulgare wheat which re¬ 
semble the emmer parent have 14 chromosomes, while those which resemble the 
vulgare parent have 21 chromosomes and that the segregates with an intermedi¬ 
ate number of chromosomes tend to become eliminated, due to sterility (11). 
In a previous study a number of F 3 segregates were found which had an inter¬ 
mediate chromosome number and others were found which had intermediate 
head type. In some cases the segregates which were recorded as having inter¬ 
mediate chromosome numbers were of the durum or vulgare type. In one case 
a segregate was classed as a durum type but had 21 chromosomes. It was con¬ 
sidered desirable to determine if the intermediate chromosome numbers and inter¬ 
mediate plant types persisted in the fourth generation, and to obtain additional 
data in regard to the relation between chromosome number and type of spike. 
One might also expect a larger proportion of F 3 and F 4 segregates to have a 
chromosome number of 14 or 21 in Amby X Kubanka than would be the case in 
the more fertile cross of Marquis X Alaska, where it might be expected that a 
comparatively large proportion of the segregates would be intermediate in 
chromosomes number as well as morphological characters. The F 4 segregates of 
these intermediate types for both Amby X Kubanka and Marquis X Alaska 
were grown in Maine in 1923. Chromosome counts were obtained with the use 
of Selling's method ( 1 ). It was not always possible to distinguish the univalent 
chromosomes from the bivalent, so that the numbers of chromosomes of each 
type could not be exactly determined. The descriptions of the F 3 and F 4 segre¬ 
gated of each cross, the chromosome number where it has been determined and 
the fertility of the F 4 segregates are shown in Table VI. 
Table VI.— Type of F 2 and F 3 segregates and chromosome number f grains per' 
spikelet (g) shown for F 4 plants. The numbers and letters correspond to numbers 
and letters of types of F 2 plants shown in Plates 1 and 2. S=single chromosomes 
AMBY X KUBANKA 
Description, 1922, Fs 
Chromo¬ 
some No. 
Description, 1923, F 4 
Chromo¬ 
some No. 
g 
Plate 2 
Dnrnm typo 
±16 
Durum type..... 
14 
1.9 
14 
1.8 
14 
1.9 
14 
0 
.do. 
±16 
14 
1.9 
do 
14+4-6 S 
14+3-4 S 
18 
14 
1.1 
TntflrmArliatA 
Intermediate__ 
18+2-4 S 
1.3 
Vulgare type. 
Vulgare type head—durum awns and grain.. 
21 
2.0 
T n term fid i at ft 
21 
Vulgare type__ 
20+1-2 S 
1.6 
do 
21 
21 
2.0 
MARQUIS X ALASKA 
f 3 
F 4 
Plate 1 
Diinim hftad-viilcrarfi kfifil 
Durum head—vulgare keel_ 
14 
0.8 
T)nmm hftad-soft grain 
Durum head—soft grain_ 
14 
2.0 
14 
1.6 
Vnliraro haaf)—dnrnm VaaI 
Branching head—hard grain_ 
18+2-3 S 
1.5 
Vulgare head—durum keel and 
Vulgare head—durum keel and awns_ 
18+2-3 S 
1.5 
dvTjuS. 
do _ _ _ _ 
Branching head—intermediate keel. 
18+2 S 
.5 
Vulgare head—intermediate 
keel—durum awns. 
Vulgare head—durum awns, soft grain, in¬ 
termediate keel. 
19+2-3 S 
2.0 
Vulgare head—intermediate keel—hard grain 
19+2-3 S 
i 
2.0 
