28 
BULLETIN 56, HAWAII EXPERIMENT STATION 
EFFECT OF STORAGE 
Determinations of the sugar content of rootstocks kept for differ- 
ent lengths of time after digging in a covered jar at room tempera- 
ture are given in Table 11. 
Table 11. — Effect of storage on sugar content of sap of canna rootstock 
Age of 
rootstock 
Time 
stored 
Sucrose 
in sap 
Hexoses 
in sap 
Total 
sugars 
in sap 
Ratio of 
hexoses to 
sucrose 
Months 
12 
12 
12 
12 
6 
Days 
........ 
115 
21 
30 
Per cent 
1.16 
2.62 
3.73 
2.73 
3.06 
Per cent 
0.13 
.33 
. 55 
.37 
.18 
Per cent 
1.29 
2.95 
4.28 
3.10 
3.24 
1 
1 
1 
1 
1 
0.112 
0.126 
0.147 
0.135 
0.059 
i Beginning to ferment. 
The table shows that the sugars of the stored rootstock increased 
continuously for about two weeks, when fermentation began. The 
hexose-sucrose ratio also increased. The rootstock which had been 
stored for 21 days was decidedly spongy and showed signs of fermen- 
tation. In this case both forms of sugar decreased but the hexose- 
sucrose ratio was nearly the same as in the rootstock which had been 
stored for eight days. That this did not hold for all the rootstocks 
is shown by the different ratio obtained in rootstocks from a 6-months- 
old hill which had given no appreciable sign of fermentation after it 
had been stored for 30 days. Unfortunately, the original sugar con- 
tent of this sample was not determined. 
The results indicate the rapidity of the changes taking place in the 
canna rootstock after it is dug. Such changes would seem to be of 
considerable significance in extracting the starch for commercial uses. 
Although the rootstock can be left in the hill for a number of months 
after maturity without deteriorating, its value for starch manufac- 
ture is greatly impaired by a few days' exposure after digging. The 
starch granules remain unaffected for some time, but purification and 
sedimentation are rendered difficult by the large amount of slimy 
precipitate which settles out even before the rootstock shows sign of 
fermentation or decay. 
DORMANT AND ACTIVELY GROWING PLANTS 
At Waimea a field of canna developed neither new steins nor rooi- 
stocks during a period of about three months. However, the stems 
already developed were protected from injury by continuous mists 
and by windbreaks. Toward the end of the dormant period a hill was 
dug for sugar determination. Two months later the field showed vig- 
orous development of both new stems and rootstocks. Another hill 
was then dug from the same section as the first. Table 1 2 compares the 
sugar content of the two hills. 
