1012 
Journal of Agricultural Research 
Vol. XXX, No. 11 
DEVELOPMENT OF PIGMENT AT 
DIFFERENT HYDROGEN-ION 
CONCENTRATIONS 
The development of pigment at dif¬ 
ferent hvdrogen-ion concentrations was 
studied concurrently with the changes 
produced in the initial P H value of the 
different cultures by the organisms. 
The determination of the particular 
color of the pigment in the different 
cultures were made by using Ridgwav’s 
Color Standards ( 8 ) and those of the 
hydrogen-ion concentrations of the cul¬ 
tures by using Clark and Lub’s (2) indi¬ 
cators for relatively clear solutions and 
Hildebrand’s (4) hydrogen electrode for 
heavily colored solutions. 
Fusarium cromyophthoron Sid. is 
treated more extensively in these studies 
than any of the other species of the same 
genus. With this organism the devel¬ 
opment of the pigment and nature of 
the reactions—that is, decreases or in¬ 
creases in the Ph value—are studied in 
connection with more nutrient sub¬ 
stances than dextrose. 
ADJUSTED CULTURES 
Changes in the initial hydrogen-ion 
concentration of the cultures of the first 
set, the adjusted set of cultures, were 
neutralized with occasional introduc¬ 
tions of 0.2 normal HC1 or NaOH for 
the purpose of maintaining constancy 
in the initial reaction of the culture. 
The influence of the reactions of the 
organism on the initial hydrogen-ion 
concentration of the culture solutions, 
possibly affecting the development of 
pigment, is probably eliminated by the 
introduction of adjusting reagents in 
the culture media for the neutralization 
of the resulting changes in the hydro¬ 
gen-ion concentration. The changes 
produced in the initial hydrogen-ion 
concentration of the culture solution 
were adjusted regularly (in 4-day in¬ 
tervals) by adjusting reagents, accord¬ 
ing to the instructions of Sideris . 4 
The results which were obtained in 
connection with the development of 
pigment by different species of Fusa¬ 
rium are recorded in Table I. 
Table I.— Color , intensity, and diffusibility of pigment produced by different 
species of Fusarium at different hydrogen-ion concentrations, and volumes of 
adjusting reagents (c. c. 0.2 normal HC1 and NaOH ) required to maintain the 
initial Ph value of the solution constant in dextrose solutions 
Organism 
Initial 
Ph 
Fusarium cromyophthoron Sid_ 
Do_ 
Do_ 
Do_ 
Do_ 
Do_ 
F. lutulatum Sher.._ 
Do_ 
Do_ 
Do_ 
Do_ 
Do_ 
F. oxysporum Scht__ 
Do_ 
Do_ 
Do_ 
Do_ 
Do_ 
F. oxysporum var. longiits Sher_ 
Do_ 
Do_ 
Do_ 
Do_ 
Do_ 
F. sclerostromaton Sid_ 
Do_ 
F. oxusporum var. resupinatum 
Sher. 
Do_ 
Do_ 
Do_ 
Do_ 
3.0 1 
4.0 j 
5.0 i 
6.0 
7.0 
7.5 j 
3.0 
4.0 
5.0 
6.0 
7.0 
7.5 
3.0 
4.0 
5.0 
6.0 j 
7.0 | 
7.5 ! 
3.0 
4.0 
5.0 
6.0 
7.0 
7.5 
3.0 
4.0 
3.0 j 
4.0 
5.0 
6.0 
7.0 
Adjusting reagent 
Color of pigment 
HC1 
NaOH 
13 
0 
Pompeian red; madder brown. 
7 
0 
Van Dyke red. 
0 
4 
Orange pink (diffusible). 
0 
27 
Flesh pink. 
0 
90 
Shrimp pink. 
0 
120 
Colorless. 
10 
0 
Pomegranate purple. 
0 
4 
Pale vinaceous. 
0 
15 
Pale orange yellow. 
0 
21 
Ivory. 
0 
64 
Colorless. 
0 
112 
Do. 
10 
0 
Flesh pink. 
0 
10 
Pale vinaceous. 
0 
15 
Venetial pink. 
0 
30 
Colorless. 
0 
45 
Do. 
0 
90 
Do. 
17 i 
0 
Eugenia red. 
5 
Vinaceous. 
0 i 
13 
Shrimp pink. 
o ! 
25 
Colorless. 
0 i 
70 
Do. 
0 
110 
Do. 
15 i 
0 
Acajou red. 
o ! 
3 
Alizarine pink. 
10 i 
1 
0 
Jasper pink. 
0 
7 
Pale salmon. 
0 | 
10 
Vinaceous lilac. 
o ! 
20 
Flesh pink. 
0 
65 
Colorless 
4 Sideris, C. P. the influence of the hydrogen-ion concentration on the development of 
THE PINK ROOT DISEASE OF ONIONS. (3 PARTS) I. THE EFFECT OF THE HYDROGEN-ION CONCENTRATION ON 
the development of fusarium cromyophthoron sid. f Unpublished thesis, Ph. D., Univ. Calif. 
