10 
BULLETIN 54, HAWAII EXPERIMENT STATION 
extract is always lowest during immaturity, while in two out of three 
instances it is higher during maturity than in the older stages. 
A comparison of the average composition by months shows no 
consistent variations other than a gradual decrease in the moisture 
content up to the twelfth month. This is to be expected because the 
ages of the mature and immature tubers of the several months are 
about the same regardless of the month of harvest. Since the tubers 
vary little in composition after they reach the mature stage, the hill 
as a whole should show little variation in composition from month 
to month. 
The twelfth-month samples show an abrupt change in composition 
as compared with samples of the preceding months. The water 
content made an average increase of more than 8 per cent, whereas it 
showed a continuous decrease in the preceding months. Coupled 
with the high protein and ash content of the immature groups, this 
change is indicative of new and quick growth. That such was the 
case is shown by the fact that at 11 months from planting, 21 hills 
of canna contained 397 immature tubers and a total yield of 183 
pounds, while at 12 months from planting, a like number of hills 
contained 671 immature tubers and a total yield of 303.5 pounds. 
Unfortunately, this field was plowed before a further study could be 
made. It is highly probable, however, that with the return of 
normal weather conditions the average composition of the hill 
eventually would have become the same as it had been in the period 
preceding the twelfth month. 
In brief, it may be concluded that after an individual tuber has 
reached maturity, which requires from 30 to 90 days, it varies little 
in composition at least for a year, except for an appreciable increase in. 
fiber content; and provided that weather conditions remain constant, 
the composition of the hill as a whole changes little. Consequently, 
the crop will have practically the same composition regardless of 
the age at which it is harvested. The best age at which to harvest 
may therefore be decided largely by the yields obtained. The 
analyses as given in the preceding table show the following to be the 
average composition of edible canna tubers : 
Chemical composition of edible canna 
Constituent 
Fresh 
material 
Oven- 
dried 
material 
Constituent 
Fresh 
material 
Oven- 
dried 
material 
Water 
Per cent 
72.62 
.98 
.11 
Per cent 
Per cent 
24.28 
.61 
1.40 
Per cent 
88. 6S 
Protein 
3.58 
.40 
2.2a 
Fat (ether extract) ... 
Ash 
5. 1L 
VARIATION IN COMPOSITION OF THE TOPS 
Since canna tops may attain maximum growth in as short a time 
as 30 days under proper climatic conditions, it would seem as though 
rapid changes in composition must take place. To permit of a. 
study of such changes, the tops of a hill 12 months old were divided 
into three stages of growth: (1) Old stage, in which the blooms were 
dead and the lower leaves were beginning to wither; (2) bloom stage; 
and (3) immature stage averaging 2 feet in height. The following 
table shows the effect of the stage of maturity on the composition 
of canna tops. 
