Jan. 1,1925 
11 
A Study of Variability in the Burt Oat 
A ratio approximating 1:3 was obtain¬ 
ed, the wild form being recessive. 
They state that the same has held true 
in a large number of other crosses in 
which the “wild” type has been used. 
In studying the segregation in the third 
and fourth generations they found no 
yellow oat exhibiting the “wild” base. 
These results agree with those of 
Surface (127), as would be expected, 
for Warburton and Stanton (146) 
believe that the sativa parents, Kherson 
and Sixty-Day, used by these different 
investigators are practically identical. 
It is known, however, that strains 
exist within each of these varieties 
which differ in kernel color and other 
characters. For instance, three pure- 
line selections from Kherson, namely, 
Albion (Iowa No. 103), Iowar, and 
Nebraska No. 21, all have white- 
glumed kernels. 
Wiggans 12 studied the basal con¬ 
nection in the cross Red Texas X 
Swedish Select. In Fi there was 
an articulation of the outer floret, but 
this was not so pronounced as in the 
Red Texas parent. All types were 
found in F 2 , ranging from the Red 
Texas to the Swedish Select type. 
The plants were classified as having 
Red Texas base, intermediate, and 
Swedish Select base, giving a close fit 
to a 1:2:1 ratio. These data indicate 
that there is only one pair of factors 
involved in determining the basal 
connection in this cross. There was 
evidence of linkage between the Red 
Texas type of base and the Red Texas 
rachilla character. 
Fraser (37), in crossing Burt and 
Sixty-Day, found the Fi basal form 
to be intermediate. In F 2 a ratio of 
three Sixty-Day to one Burt type of 
base was obtained. His results pointed 
to the existence of linkage between 
the Burt type of base and the fully 
awned condition. There also was 
evidence of linkage between the Burt 
base type and the presence of medium 
long basal hairs. Fraser stated that 
4.14 per cent of crossovers occurred 
between awns and base type and that 
there was 1.79 per cent of crossing oyer 
between base tvpe and basal hairs. 
He states that the strain of Burt used 
as parental material in these crosses 
had a dense covering of mid-length 
hairs on the sides of the basal callus 
and that the lower kernel had an 
articulation much like that of Avena 
sterilis. The Sixty-Dav parent had 
the base and articulation characteristic 
of Avena sativa. Basal hairs seldom 
were present. 
FLORET DISJUNCTION 
The florets of an oat spikelet are 
connected bv the clavate segments of 
the rachilla. The articulation at the 
juncture of two segments is not very 
evident, owing to the structure of the 
spikelet. The base of the lemma of 
each floret is attached to the enlarged 
apex of the segment which bears it 
and entirely surrounds the slender base 
of the segment which bears the next 
higher floret. This latter segment 
therefore appears to grow out from the 
basal tissue of the inrolled lemma next 
below. 
When florets of A. byzantina, the 
cultivated red oats derived from A. 
sterilis , are separated the rachilla seg¬ 
ments bearing the second and third 
florets usually remain attached to the 
bases of those florets. When florets of 
A. sativa , the cultivated oats derived 
from A. fatua , are separated the bear¬ 
ing segments usually disarticulate from 
the base of the floret and remain at¬ 
tached to the face of the next lower 
floret. 
The attachment of the rachilla seg¬ 
ment to the base of the second and 
subsequent florets in A. byzantina is 
very firm. In threshing the florets of 
the spikelet often remain attached to¬ 
gether. When they are forcibly separ¬ 
ated the segment breaks near its base, 
as pointed out above. In A . sativa , 
on the other hand, the separation by 
disarticulation at the base of the floret 
takes place very readily. 
Norton (99) apparently was the first 
American investigator to call attention 
to the firm union of the first and second 
florets with their connecting rachilla 
segment in the cultivated varieties de¬ 
rived from Avena sterilis. 
Trabut (135) made use of this char¬ 
acter in his classification of oats. He 
states, however, with regard to Avena 
barbata that— 
there is little difficulty in finding all the characters 
of Avena barbata, not taking into account the func¬ 
tioning of the articulation and the pilosity. two 
fluctuating characters without value, as we have 
seen in Avena sterilis and Avena fatua. 
Etheridge (33) states that the specific 
character of connection of the kernels 
has not been used extensively before 
in the classification of cultivated varie¬ 
ties of oats. He found this character 
to be of great value for distinguishing 
the cultivated forms of Avena sterilis 
from those of Avena fatua. In his 
review of the literature on oat classi¬ 
fication he refers to Denaiffe and 
Sirodot (26) and to Broili (12) as using 
the form and hairiness of the rachilla 
12 Wiggans, R. G. the inheritance of certain characters in a cross between red texas and 
SWEDISH SELECT oats. 1918. [Unpublished thesis, Cornell Umv, Dept. Plant Breeding.] 
