Jan. 1, 1925 
A Study of Variability in the Burt Oat 
17 
Avena nuda, said to be impure as 
regards color, and the white-husked 
varieties Thousand Dollar and Ligowa, 
which were a mixture of grays and 
whites. The presence of grays demon¬ 
strated, however, the dominance of 
the gray color whenever the cross 
gray X white actually occurred. 
In another cross, Nubian Black X 
Avena nuda, the Fi color was a bright 
brown sometimes overlaid with a faint 
grayish flush. Here the Fi also may 
vary because the black parent is genetic¬ 
ally really made up of at least three dif¬ 
ferent kinds of blacks, represented 
zygotically by the formulae BB B'B' GG, 
BB B'B' gg, and BB b'b' gg, where B 
and B' are factors for blackness and 
G for gray color. In F 2 a ratio of 
approximately 3 gray to 1 white was 
observed. There was no linkage or 
repulsion of gray or brown color with 
tight paleas. 
Caporn reports in another paper (15) 
on a cross between Mesdag, a variety 
with dark-brown florets and distinct 
affinities with Avena fatua , and Hope- 
town, a white-glumed variety. The 
Fi florets were somewhat lighter brown 
than those of Mesdag. No data on 
the inheritance of color in F 2 are given. 
Love and Craig (70) present data 
on a cross of Avena fatua and Avena 
sativa, variety Sixty-Day. The result 
obtained in this cross corresponds very 
closely with that obtained by Surface 
(127 ). They assumed that Avena fatua 
carries color genes for black, gray, and 
yellow, and that Sixty-Day has the 
gene for yellow. They found a strong 
indication of an inhibitory factor or 
factors which prevent not only awn 
development but also the wild form of 
lemma base and pubescence in combi¬ 
nation with yellow color of the lemma. 
Love and Craig (71) found that in 
crosses between the Sixty-Day oat and 
the wild Avena fatua the yellow color 
of the Sixty-Day inhibits the produc¬ 
tion of well-developed awns and pubes¬ 
cence on the glumes. These crosses 
also have shown that different types 
are found in A. fatua. One sort when 
crossed with the White Tartar King 
gives 15 plants with lemmas pubescent 
to 1 nonpubescent in the second gen¬ 
eration, while another type produces 
a ratio of 3 pubescent to 1 nonpubes¬ 
cent. Two forms of black oats classed 
as the same variety produced plants 
with white florets in the second genera¬ 
tion in the ratio of 15 black to 1 
nonblack. 
Meunissier (77) states that white 
glume color is recessive to other colors. 
Pridham (106) quotes A. E. V. 
Richardson, of Australia, as having 
mentioned that in oats all the different 
tints of kernel color appear to be Men- 
delian dominants to colorless or white. 
Wiggans 20 studied the inheritance of 
kernel color in the Red Texas X 
Swedish Select cross. The color of 
the Fi florets was red, although a 
somewhat lighter red than that of the 
red parent grown under the same con¬ 
ditions. Floret color, as developed 
under greenhouse conditions, proved 
to be a difficult character to work with. 
Four types were evident in F 2 , red, 
gray, white, and yellow, although ac¬ 
curate classification was practically 
impossible. The data indicate that 
there is more than one pair of factors 
which determine color. The factor 
for red is the dominant one. 
Fraser (87), in crossing Burt (red) 
with Sixty-Day (yellow), found Fi to be 
intermediate in color. In F 2 difficul¬ 
ties in classification were experienced 
because of the gradation of colors and 
the influence of environmental factors. 
An approximate ratio of 48 :eds : 15 
yellows : 1 white was observed in F 2 . 
Fraser considers that Burt carries two 
color factors, red and yellow, while 
Sixty-Day has only the factor for 
yellow. 
According to Fraser (37) the genetic 
formula for floret color in the Burt 
variety would be RRYYy'y'. The 
variety Sixty-Day would have the 
genetic formula rryyY'Y'. He states 
that the results in the F 3 genera¬ 
tion bear out this theory in a general 
way. He believed that because of the 
yellow color factor in the Burt variety 
which carries no inhibitor for awns, the 
inhibitory effect of the Sixty-Day fac¬ 
tor was obscured. Fraser considered 
the few brown florets which appeared 
in the course of his studies to be the 
result either of mutation or of reversion. 
Wakabayashi (140) reported a cross 
between Avena sterilis , variety Red 
Rustproof, and Avena sativa orientalis, 
variety Black Tartarian. He found 
the black color of Black Tartarian to be 
a simple Mendelian dominant, and 
believed that there was some linkage 
between white color and susceptibility 
to smut. 
PRELIMINARY OBSERVATIONS 
Apparently one of the first persons 
to recognize the variability of the Burt 
oat was J. B. Norton, formerly en¬ 
gaged in oat breeding in the United 
States Department of Agriculture. He 
*° Wiggans, R. G. op. cit. 
