917 
May 15,1925 Inheritance of Botanical Characters in Barley 
contained all the types of F 2 . The 
results are explained on the basis of 
one main factor difference between 
rough awn and smooth awn. 
Teeth on the glumes. —Three kinds 
of teeth on the glumes of barley are 
described by Ubisch {23, v. 17). 
Teeth of type (a) are visible to the 
naked eye, type ( 6 ) are seen by the 
aid of a hand lens, while type ( c ) can 
be seen only with a microscope. In 
crosses of type (a) with a nontoothed 
variety an intermediate toothed condi¬ 
tion was obtained in F b and in the F 2 
there were 3 toothed and intermediate 
forms to 1 nontoothed. 
Hulled and naked seed.- -The 
naked condition of the seed seems to 
be a simple recessive to the covered. 
Hayes and Garber ( 8 ) cite the results 
of Gaines and also Thatcher in which 
the naked condition behaved as a 
simple recessive to the covered. 
Ubisch {23, v. 20) obtained results 
which indicated that the hulled condi¬ 
tion was not completely dominant, 
although the results could be explained 
on a single factor basis. 
Dwarf forms. —Harlan and Pope 
(7) describe a dwarf barley which 
measured only about 50 cm. from the 
crown of the plant to the tip of the 
awns. The dwarf form behaved as a 
simple recessive to the normal barley. 
On the other hand, a dwarf was 
obtained by Mivazawa {12) which 
tended to be dominant to the normal. 
The homozygous dwarfs were some¬ 
times so small as to escape notice and 
were sterile. Occasionally a dwarf 
plant died in the seedling stage. A 
single factor difference explains the 
results obtained. 
Chlorophyll deficiences. —Seed¬ 
ling types deficient in chlorophyll have 
been found in several of the cereals, so 
it is not surprising to find that they also 
occur in barley. They have been 
observed in two Minnesota varieties, 
but their mode of inheritance has not 
been studied. Hallquist {3) obtained a 
chlorophyll-defective barley strain 
which is dependent on temperature 
for its expression. At 0° to 10° C. no 
chlorophyll develops, at 12° to 15° 
some green color develops but the seed¬ 
lings are very yellow, while at 20 ° the 
seedlings are normal green in color 
almost from the time of their emer¬ 
gence. The defect behaves as a 
simple recessive to the normal green. 
Back crosses of the heterozygotes to 
the normal green gave results which 
differed depending on whether the 
normal was used as the female or as 
the male parent. The results are 
explained by assuming a single factor 
difference between the normal and the 
defective and a partial elimination of 
the male gametes which carry the 
recessive factor. 
Six different chlorophyll defects are 
described by Nilsson-Ehle {14, 13), 
three whites, two yellows, and a 
chlorina. The three whites have been 
shown by breeding tests to be different 
genotypically. The yellows have not 
been tested thoroughly but differ 
phenotypically. The chlorina cor¬ 
responds to the virescent types in 
corn in that under the proper cultural 
conditions it lives and produces seed. 
Each of the abnormal types behaves 
as a simple recessive to the normal 
green. 
A mutation was discovered by Kiess¬ 
ling {11) which differed strikingly 
from the parent variety in many mor¬ 
phological and physiological characters, 
including a light green color of the 
foliage. The deviations from the nor¬ 
mal, other than that of chlorophyll, are 
considered by Kiessling as incidental 
to the chlorophyll deficiency. The 
abnormal type, like those studied by 
Nilsson-Ehle, is a simple recessive to 
the normal. 
Disease resistance. —Nilsson-Ehle 
{15) made a study of the inheritance in 
barley of the manner of reaction to the 
nematode disease caused by Heterodera 
schachtii. The cross Chavalier X Gold, 
inunune and susceptible varieties, re¬ 
spectively, gave Fi plants which were 
immune and the segregation in F 2 , as 
shown by the breeding behavior in F 3 , 
approximated a 3:1 ratio. These re¬ 
sults show susceptibility to be a simple 
recessive to immunity. 
Studies have been made by Hayes et 
al {10) on the inheritance of the manner 
of reaction in barley to Helmintho - 
sporium sativum. A careful study was 
made in a cross of a resistant variety 
with a highly susceptible variety. One 
hundred and twenty-four F 3 lines were 
grown under epidemic conditions in 
comparison with the parent varieties. 
The number of homozygous resistant 
and susceptible lines was determined 
from a test of F 3 and F 4 families. It 
was pointed out that the results could 
be explained by assuming two pairs of 
factors to be involved. The presence 
of both factors leads to the production 
of highly resistant forms while the ab¬ 
sence of both gives highly susceptible 
forms. 
Color in glumes. —Black color in 
the glumes behaves as a dominant to 
white, and in all results so far obtained 
a single factor difference exists between 
black and white. Purple color in the 
glumes is also dominant to white, and 
