REGARDING THE POSSIBLE ADAPTATION OF SOY BEAN 
RADI Cl COLA TO A SPECIFIC HOST VARIETY 1 
By Alfred T. Perkins, 2 
New Jersey Agricultural Experiment Station 
INTRODUCTION 
It has been noted by several in¬ 
vestigators that the number of nodules 
formed on the roots of soy beans vary 
in different varieties. J. H. Vorhees 3 
reported a case where Haberlandt soy 
beans failed to produce nodules, even 
though they were growing with their 
roots intertwined with those of other 
varieties which produced nodules. 
Later experiments have shown that 
Haberlandt soy beans will produce 
nodules, but usually to a less extent 
than other varieties. The question 
naturally arises as to what this dif¬ 
ference in nodulation may be at¬ 
tributed. Theoretically, there are at 
least two possibilities: First, the bac¬ 
teria might become adapted, in part 
at least, to the host variety with which 
they had been growing in symbiotic 
relationship; second, the specific host 
varieties of soy beans might possess 
different physiological characteristics 
which would tend to render the several 
varieties immune to infection in dif¬ 
ferent degrees. 
EXPERIMENTAL DATA 
Assuming that it is possible for the 
bacteria to become partially adapted 
to a specific host variety, the author 
grew a culture obtained from a single 
bacterial cell and inoculated Virginia, 
Haberlandt, Mammoth Yellow, and 
Wilson soy beans with it. As soon 
as the inoculations were made, the 
seeds were planted in fertilized, washed 
sand free from nodular organisms. 
When nodules appeared new isolations 
were made, and the cultures were 
inoculated back upon the same host 
variety. Isolations were again made 
and the cultures which had twice 
passed through the symbiotic rela¬ 
tionship with the same host variety 
were used in the subsequent tests on 
the adaptation of the organism to a 
specific host variety. The tests were 
conducted in the greenhouse under 
carefully controlled conditions and in 
the field where unknown and uncon¬ 
trollable factors necessarily played a 
part. The results of the two series 
of experiments agreed very well. 
The tests conducted in the green¬ 
house were made in flats 2 feet by 2 
feet by 4 inches. The flats were filled 
with washed sand fertilized with mag¬ 
nesium sulphate, monobasic potassium 
phosphate, calcium carbonate, and 
ferrous sulphate at the respective 
rates of 15, 30, 100, and 10 pounds per 
acre. The inoculations were made by 
applying the nodular organism directly 
to the sand. The moisture content 
of the substratum was maintained by 
saturating it daily with distilled water. 
Four flats were used, one for each 
culture. Each flat was divided into 
nine sections by stretching strings 
across the top, and plantings were made 
with Tokyo, Hollybrook, Mammoth 
Yellow, Wilson, Virginia, Tar Heel, 
Haberlandt, Guelph, and Ito San soy 
beans. After four weeks’ growth the 
crops were harvested and the data on 
nodulation obtained. These indicate 
that by twice passing through the 
symbiotic relationship with a specific 
host the organism does not become 
better adapted to that host than to 
other host varieties. In every case, 
regardless of the source of the organism, 
the Mammoth Yellow soy beans 
produced a greater number of nodules 
than the other varieties tested. Like¬ 
wise, Haberlandt and Ito San always 
produced fewer nodules than the other 
varieties. These two varieties nodu¬ 
lated approximately to the same 
degree. In the four cases the relative 
number of nodules produced by the 
various hosts was about the same, and 
no data were obtained which indicated 
the least adaptation of the nodular 
organism to a specific host variety. 
The data secured from the greenhouse 
experiments are given in Table I. 
1 Received for publication June 11,1924; issued April,1925. Paper No. 174 of the Journal Series, New Jersey 
Agricultural Experiment Station, Department of Soil Chemistry and Bacteriology. This article is part 
of a thesis presented to the faculty of Rutgers College in partial fulfillment of the requirements for the 
degree of doctor of philosophy. 
2 The writer wishes to express his appreciation to Dr. J. G. Lipman for helpful suggestions in the plan¬ 
ning of this work. 
3 Voorhees, J. H. variations in soy bean inoculation Jour. Amer. Soc. Agron. 7:139-140. 1915. 
Journal of Agricultural Research, 
Washington, D. C. 
( 243 ) 
Vol. XXX, No. 3 
Feb. 1, 1925 
Key No. N. J.-12. 
