Nov. 15, 1925 
Growth-Equation Constants in Crop Studies 
977 
for growth in pounds is varied, being expressed uniformly as a per¬ 
centage of the theoretical total or final growth. The sunflower equa¬ 
tions may be converted to the average individual plant (upwards of 
6 inches above ground) by dividing A by 14,662. The corn equa¬ 
tions may be converted to the average individual plant (above 
ground) by dividing A by 10,000. Just what effect this difference 
in density of the population may have caused in the constants of 
the sunflower and corn equations the writers have no means of know¬ 
ing precisely. Theoretically, A/K should not be affected by this or 
other environmental factors. At the present stage, of course, the 
whole theoretical matter may be regarded as no more than a working 
hypothesis. 
CRUDE FIBER AND ALUMINUM IN THE SUNFLOWER 
Crude fiber is a constituent of the plant customarily determined 
in feed analyses. It consists principally of the, cellulose tissues of the 
plant. This constituent corresponds in a way to the skeleton of an 
Fig. 2.—Growth of crude fiber in stalk per acre of sunflower crop. Time (t) is reckoned in days from 
date of planting. Growth ( x ) is expressed as a percentage of 2,700 pounds. Equation to curve: 
log 270^=0.033 (*-78.5) 
animal, and affords a good measure of growth in size or volume of 
the plant. The observations and fitted curve for the crude fiber in 
the stalk 8 are shown in Figure 2. The curve gives a fair fit to the 
observations, although a considerably better fit is obtained by a 
logical modification, as shown in Figure 4. The curve is presented 
in the form given in Figure 2 partly for the sake of comparison with 
Figure 3, which pertains to aluminum. 
The observations and fitted curve for aluminum are shown in 
Figure 3. Considerable irregularity is manifest in the aluminum 
8 The seeds were separated carefully by hand, and the stalk includes the remainder of the head and 
plant as cut 6 inches above ground. In the case of the corn the ears (that is, cob and kernels together) 
were separated, and the stalk includes the remainder of the ear (husk and shank) and plant as cut at 
ground level. 
