BULLETIN 54, HAWAII EXPERIMENT STATION 
VARIATION IN COMPOSITION OF THE TUBERS 
In order to determine what progressive changes take place in the 
composition of the tubers, samples for analysis were harvested each 
month from a field at the station, beginning with the sixth month 
after planting and continuing through the twelfth month. Only 
one sample was analyzed during each of the first three months. As 
the work progressed it became apparent that, due to the short life 
cycle of the canna, the variations in the composition of tubers within 
a single hill were greater at any time than they were between compos- 
ite samples that were harvested a month apart. In order to deter- 
mine the monthly variations of the entire hill and the individual 
differences taking place within the hill,*the tubers harvested during 
the last three months were divided into three groups having the 
following characteristics : 
(1) Old tubers (cylindrical to oval in shape). The tops of the 
tubers were dead. The gradual tapering of the tuber, as compared 
with tubers in group 2, shows that in the late stage of growth starch 
is stored in the lower two or three inches of the stalk, which then, 
for starch manufacture, becomes an integral part of the tuber. 
(2) Mature tubers (oval to round in shape). The plants had 
reached the bloom stage. The tubers were mature and had attained 
their maximum diameter. 
(3) Immature tubers (round in shape). The tops of the plants 
were either just above ground or had not as yet emerged. The tubers 
were of course smaller than in case of either of the preceding groups. 
Roots, dead scales, and adhering soil were all removed from the 
tubers as soon as they were dug. After being weighed, shredded, 
and dried, the tubers were analyzed by the methods recommended 
by the Association of Official Agricultural Chemists. 10 
Chemical analyses of the tubers, which were harvested monthly, 
are given in the following table : 
Effect of stage of maturity of harvesting on the percentage composition of edible canna 
tubers a 

Water 
Protein 
Fat 
Carbohydrates 
Age 
Nitrogen- 
free 
extract 
Crude 
fiber 
Ash 
Fresh material 
Six months ..... 
Per cent 
80.58 
77.53 
76.09 
Per cent 
0.94 
.71 
.56 
Per cent 
0.07 
.08 
.09 
Per cent 
16.72 
19.95 
21.62 
Per cent 
0.40 
.39 
.40 
Per cent 
1.29 
Seven months. . 
1.34 
Eight months... 
1.24 
Nine months: 
Mature 6 
70.10 
77.26 
.77 
.94 
.10 
.08 
27.10 
19.74 
.67 
.51 
1.26 
Immature . 
1.47 
Average . .. .. 
73.68 
.86 
.09 23.42 
.59 
1.36 
Ten months: 
Old 
72.49 
68.78 
76.18 
.79 
1.01 
1.25 
.12 
.12 
. 11 
24.41 
28.25 
20.44 
.79 
.51 
.48 
1.40 
Mature 
1.33 
Immature .. 
1.54 
Average . 
72.48 
1.02 
. 12 24. 37 
.59 
1.42 
« The results are given on the oven-dry weight as well as on the fresh material because the former brings 
out more clearly the variations in the composition of the different groups of tubers. 
t> Sample includes both old and mature tubers. 
10 Methods of analysis orthe Association of Official Agricultural Chemists, sec. VII, p. 71-99. Revised to 
Nov. 1, 1919, Washington. D. C, 1920. 
