BRITTLE STRAW AND OTHER ABNORMALITIES IN RYE 1 
By F. R. Davison, H. E. Brewbaker, and N. A. Thompson, Division of Plant 
Pathology and Botany , Minnesota Agricultural Experiment Station 
In America rye is of minor importance as a grain crop; consequently there has 
been relatively little time devoted to its improvement. However, rye combines 
many desirable qualities such as winter hardiness, wide soil adaptation, quick 
growth, and good yield. It seems probable, therefore, that it will eventually 
find wider favor in this country. 
Two general methods of improvement of rye are employed at the Minnesota 
Agricultural Experiment Station, namely, bulk selection for purity of seed- 
color and for vigor of the plants, and selection in self-fertilized lines. Minnesota 
No. 2 rye, which originated at Minnesota as a result of selection for winter 
hardy plants in Swedish rye, has been used for all of the inbreeding work. Since 
rye is normally cross-fertilized, commercial varieties are ordinarily heterogeneous 
mixtures for seed color and plant type. Both of these methods of breeding 
seek the isolation of vigorous uniform types, and hence may be considered 
respectively as broad and narrow types of inbreeding. 
One of the interesting features of these studies at Minnesota is the occurrence 
of certain types of abnormalities, in inbred strains. Since the normal type is 
usually dominant when in the heterozygous condition such abnormalities are 
seen only rarely in a commercial variety. Inbreeding, either by selection or 
by self-fertilization, brings about a recombination of the recessive abnormality 
factors and results in the appearance of abnormal plants in the inbred strains. 
This is of the utmost importance since it gives the plant breeder an opportunity 
to isolate vigorous desirable types and to discard the undesirable ones. It is the 
purpose of this paper to present some of the data at hand regarding these ab¬ 
normalities, with particular reference to one called “brittle’ 7 on account of the 
ease with which the straw breaks. 
Chlorophyll deficiency is of common occurrence as an abnormality in inbred 
strains of rye. In 1922, white or “albino” seedlings were found in nearly 25 
per cent of the self-fertilized strains and in more than 50 per cent of the strains 
originated by bulk selection, as shown in Table I. 
Table I.— Occurrence of chlorophyll-deficient abnormalities in inbred strains and 
in normal Minnesota No. 2 rye t in 1922 
Strains 
isolated 
by bulk 
selection 
Self- 
fertilized 
strains 
Normal 
Minne¬ 
sota No. 
2 rye 
Number of strains in the rye nursery. 
18 
13 
0.4-32.4 
3 
200 
45 
4-60 
23 
Number of strains segregating for white seedlings. 
Range of percentage of white seedlings to normal green seedlings in the 
inbred strains... 
0.04 
Number of strains segregating for other types of chlorophyll abnormalities. 
1 Received for publication Nov. 22, 1923. 
Journal of Agricultural Research, 
Washington, D. C. 
( 169 ) 
Vol. XXVIII, No. 2 
April 12,1924 
Key No. Minn .-50 
