INFLUENCE OF TEMPERATURE AND INITIAL WEIGHT 
OF SEEDS UPON THE GROWTH-RATE OF PHASEOLUS 
VULGARIS SEEDLINGS 1 
By Willem Rudolfs 2 
Biochemist , New Jersey Agricultural Experiment Station 
INTRODUCTION 
In the recent extensive publications upon quantitative aspects of 
growth of plants, the present state of this work is adequately summarized. 
The study reported in this paper was conducted in an attempt to discover, 
first, the direct influence of temperature upon the growth curves of plants 
when as many environmental factors as possible were controlled, and, 
second, to determine the influence of initial weight of seeds upon the 
rate of growth of the plants under such conditions. 
EXPERIMENTAL RESULTS 
A large number of seeds of Phaseolus vulgaris (beans) were selected 
according to their initial weights. Those designated as “small seeds” 
weighed (air dry) from 6.92 to 7.23 gm. per 50 seeds, and those desig¬ 
nated as “large seeds” weighed from 13.52 to 14.41 gm. per 50 seeds. 
The seeds were placed on top of greenhouse soil kept at a moisture con¬ 
tent of 60 per cent of the water-holding capacity. As soon as the seeds 
germinated they were covered with a thin layer of soil and placed in 
dark incubators, subject to accurate humidity control (60 per cent 
relative humidity), and kept at definite temperatures of 5 0 , io°, 15 0 , and 
20 0 C. The elongation of the shoots and of each internode was meas¬ 
ured daily in millimeters at approximately the same hour, care being 
taken to start each time with the same individuals. Measurements were 
taken until the seedlings collapsed or the plants stopped growing. The 
greatest height reached by any group of seedlings was nearly 28 cm. 
(20° C.), while the group of seedlings grown at 5 0 C. attained a height of 
less than 2 cm. The average readings of from 20 to 50 individuals were 
fitted to Robertson’s 3 autocatalytic formula: 
iog-^=* «-«. 
In this equation a is the final size of the organism; x is the size of the 
organism at time t; and t x is the time at which the organism has reached 
a 
half its final size, or when % = —; and A is a constant. Robertson’s 4 
2 
tables for the computation of curves of autocatalysis were used to check 
the calculations. 
1 Accepted for publication November i, 1923. This is paper No. 145 of the Journal Series, New Jersey 
Agricultural Experiment Station, Department of Soil Chemistry and Bacteriology. 
2 The writer is indebted to Earl S. Harris, formerly junior chemist. New Jersey Agricultural Experiment 
Station, for the help rendered in calculating the results herein reported. 
8 Robertson, T. Brailsford. tables for the computation op curves op autocatalysis, with espe¬ 
cial reference to curves op growth. In Univ. Calif. Pub. Physiol., v. 4, p. 211-228. 1915. 
< Robertson, T. Brailsford. further remarks on the normal rate op growth op an individual, 
and its biochemical SIGNIFICANCE. In Arch. Entwicklungsmech. Organ., Bd. 26, p. 108-118. 1908. 
Journal of Agricultural Research, Vol. XXVI, No. n 
Washington, D. C. Dec. 15, 1923 
aii Key No. N. J. -10 
(537) 
