Germination of Seed of Koa Haole {Leucaena glauca (L.) Benth.)^ 
Ernest K. Akamine^ 
The data in this paper attest to the accuracy 
of a statement by the author to the effect that 
untreated seed of koa haole {Leucaena glauca 
(L.) Benth.) may require several years to 
germinate under natural conditions (Aka- 
mine, 1942 ). The question has been raised as 
to the actual time required for the seed to 
germinate; consequently, germination tests 
were conducted in soil flats in the greenhouse. 
Each test lot consisted of 1,000 seeds, with 
emergence of seedlings as the criterion of 
germination. Weekly germination counts 
were made and sprouted seedlings were re- 
moved from the flats. The soil was kept moist 
throughout the germination period, and op- 
timum conditions for germination were main- 
tained, Seeds that were held for a period of 
time prior to germination were stored at room 
temperature. 
Results, shown in Figure 1, indicate that 
1-month-old seed of one lot germinated more 
than 90 per cent in 1 year, whereas seed of 
similar age, but of another lot, germinated 
only approximately 20 per cent in nearly 4 
years. Germination of the 2-month-old seed 
of one lot differed from that of another lot, 
as did the germination of the 10-month-old 
seed, although not to the extent of the other 
age groups. 
Delayed germination in koa haole seed is 
caused by an impervious seedcoat ("hard” 
seed) (Akamine, 1942). The differences in 
1 Published with the approval of the Director of 
the University of Hawaii Agricultural Experiment 
Station as Technical Paper 215. Manuscript received 
December 15, 1950. 
2 Junior Plant Physiologist, University of Hawaii 
Agricultural Experiment Station. 
germination of the various seed lots were 
found to be related to the differences in the 
percentage of hard seeds, i.e., the higher 
the percentage of hard seeds, the lower the 
rate of germination. These seeds, recovered 
from the slow germinating lots at the end of 
the experiment, germinated rapidly when 
scarified with sulfuric acid or nicked with a 
knife. The results indicate that the least dor- 
mant seed requires about 1 year for maximum 
germination, but that the more dormant the 
GERMINATION PERIOD -* MONTHS 
Fig. 1. Germination of koa haole seeds of different 
ages and lots. 
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