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Green-seeds.com:
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Horticulture Digest #107
PALM SEED GERMINATION
The
production of indoor tropical foliage plants in Hawaii has increased significantly
over the past 20 years. This growth peaked in 1990 with a wholesale value
of $14.6 million with about 30% of this production in palms.
Palms
are generally slow growing, but the growing conditions found in Hawaii
give our growers an advantage with year round growing conditions. Palms
are generally propagated from seeds, but growers have reported that many
palm species are slow to ge rminate or are irregular in their germination
pattern. This is a summary of some of the observations and research findings
relative to palm seed germination at the University of Hawaii.
Seed Collection
 It is generally
recommended to collect mature seeds from the tree, as those collected from
the ground are often infested with seed weevils. Maturity is indicated by
a color change, usually from green to that appropriate for the species (red,
yellow, black, etc.). Most palm seeds have a short storage life, so they
should be planted when fresh.
We also recommend
removal of the fleshy seed coat, as it often contains a germination inhibitor,
unless you have had experience with the species. The seed coat effect is
illustrated in Table 1 which shows a difference between 2 species of Pritcha
rdia (Yoshii & Rauch, 1989a). T50 is a measure of how long it takes
50% of the seeds to germinate (Orchard, 1977).
Table 1. The effect of seed coat removal on germination of palm
seeds.
Final
Treatment
T50 germination
(wks) (percent)
Pritchardia hildebrandi
With
7.6 90
Without
1.9 76
Pritchardia thurstonii
With
2.9 96
Without 2.1
96
We tried a simple bioassay
of the seed coat of areca palm (Chrysalidocarpus lutescens) by removing
the fleshy pericarp, macerating the pulp in a blender, and filtering through
a cheesecloth and then filter paper (Rauch & Crivellone, 1989). This
so lution was used to germinate lettuce seeds compared to seeds watered
with deionized water (Table 2). Clearly, the solution derived from the palm
fruit pericarp inhibited germination of the lettuce seed.
Table 2. Bioassay test of areca palm seed pericarp solution.
Days Lettuce seed germination percentage
Water control
Pericarp solution
1
86.7
0
2
89.3
0
7
91.3
0
Preplant Treatments 
There have been
a number of other preplant seed treatments proposed to improve the germination
of palm seeds, such as soaking in water with or without chemicals. In earlier
trials, we found that presoaking the seeds in water or gibberellic acid
(GA) solu tions increased the germination percent of areca palms (Rauch,
Schmidt & Murakami, 1982). However, with bamboo palm (Chamaedorea seifrizii),
the water soak proved beneficial, but there was no response to the GA treatment
(Table 3) (Yoshii, Rauch & Okazaki, 1989).
Our current recommendation
is to soak the cleaned palm seeds in water for 3 days prior to planting,
changing the water each day.
Table 3. The effect of water and 48 hour GA pre-soak treatments
on germination of Chamaedorea seifrizii seeds after 23 weeks.
Final
Treatment
T50 germination
(wks) (percent)
Untreated control
11.1 ab 67 a
24 hr water pre-soak 11.4
ab 52 a
48 hr water pre-soak 12.0
a 57 a
72 hr water pre-soak 9.8
b 56 a
100 ppm GA pre-soak 11.6 ab
72 a
1000 ppm GA pre-soak 10.8 ab
59 a
2000 ppm GA pre-soak 11.1 ab
59 a
Mean separation in columns
by Duncan's multiple range test, 5% level.
Postplant Treatments
There is very
little information on the best medium for germinating palms. To date the
results are somewhat mixed as germination was better in the well-drained
cinder or perlite than peat moss as shown in Table 4 for the germination
of Ptychosperma mac arthuri seeds.
Table 4. The effect of media on germination of Ptychosperma
macarthuri seeds after 14 weeks.
Final
Treatment
T50 germination
(wks) (percent)
Cinder
8.5 a 60 ab
Peat:cinder (1:1)
8.2 ab 35 c
Peat
7.3 bc 46 bc
Peat:perlite (1:1)
7.1 c 32 c
Vermiculite
7.0 c 56 ab
Perlite
6.7 c 63 a
Perlite:vermiculite (1:1) 6.5 c
60 ab
Mean separation in columns
by Duncan's multiple range test, 5% level.
However, there was no
difference due to the medium in the germination percent of Pritchardia thurstonii
seeds in Table 5 (Yoshii & Rauch, 1989a).
Table 5. The effect of media on germination of Pritchardia thurstonii
seeds after 14 weeks.
Final
Treatment
T50 germination
(wks) (percent)
Perlite
3.1 a 97 ab
Cinder
2.5 b 93 c
Vermiculite
2.4 bc 97 abc
Perlite:vermiculite (1:1) 2.4 bc
94 bc
Peat
2.3 bcd 98 a
Peat:perlite (1:1)
2.1 cd 98 a
Peat:cinder (1:1)
2.1 cd 96 abc
Mean separation in columns
by Duncan's multiple range test, 5% level.
One of the more beneficial
treatments for enhancing the germination of palm seeds is bottom heat (Donselman,
1982). The suggested medium temperature is 95 to 105°F. This is especially
beneficial for slow to germinated seeds such as bamboo palm (Table 6). Germination
can be reduced from 8 months to 8 weeks (Yoshii, Rauch & Okazaki, 1989).
Table 6. Effect of medium temperature on germination of Chamaedorea
seifrizii seeds after 20 weeks.
Final
Temperature
T50 germination
(+/- 1°C)
(wks) (percent)
Unheated control
0.0 a 0 b
25
0.0 a 0 b
30
10.8 b 60 a
35
9.0 c 62 a
Mean separation in columns
by Duncan's multiple range test, 5% level.
Areca palm seeds were
germinated using a combination of the better treatments (Table 7). While
most of the treatments proved beneficial in improving the germination rate,
the best was a combination of water presoak and bottom heat (Yoshii &
Rauch, 1989b). It should be pointed out that for the most part we have only
been able to improve the rate of germination and not the germination percent.
Table 7. The effect of temperature, water and GA combinations
on germination of areca palm seeds Chrysalidocarpus lutescens Wendl. after
20 weeks.
Final
Treatment
T50 germination
(wks) (percent)
Control-no treatment
6.4 a 94 ab
100 pm GA pre-soak
6.2 ab 89 b
Water pre-soak
6.1 bc 95 ab
Bottom heat
5.8 c 93 ab
100 ppm GA pre-soak
+ bottom heat
5.4 d 95 ab
Water pre-soak + bottom heat 5.1 e
97 a
Mean separation in columns
by Duncan's multiple range test, 5% level.
Transplanting
In trials to determine
the best time to transplant palm seedlings, we found that the spike or 1st
leaf stage was best (Murakami & Rauch, 1984). This resulted in less
transplant shock and plant loss.
Summary
-
Use fresh seeds harvested from the tree
-
Remove fleshy seed coat
-
Use preplant water soak treatment
-
Plant shallow in a well-drained mix
-
Use 95°F bottom heat
-
Transplant at spike or 1st leaf stage.
Fred
D. Rauch, rauch@hawaii.edu
Specialist in Horticulture
LITERATURE CITED
Donselman, H.
1982. Palm seed germination studies. Proc. Florida State Hort. Soc. 95:
256-257.
Murakami, P. K.
and F. D. Rauch. 1984. The effect of age and handling on the subsequent
growth and development of Chrysalidocarpus lutescens seedling. Jour. Envir.
Hort. 2(3): 91-93.
Orchard, T. J.
1977. Estimating the parameters of plant seedling emergence. Seed Sci. Tech.
5:61-69. Rauch, F. D., L. Schmidt & P. K'. Murakami. 1982. Seed propagation
of palms. Inter. Plant Prop. Soc. Proc. 43:341-347.
Rauch, F. D. &
C. F. Crivellone. 1989. Palm seed inhibitor study. Hawaii Nursery Research.
Univ. of Hawai'i Res. Ext. Series 103:27.
Yoshii, C. M.
& F. D. Rauch. 1989a. The effect of media and seed cleaning on the germination
of selected palm seed. Hawaii Nursery Research. Univ. of Hawai'i Res. Ext.
Series 103:25-26.
Yoshii, C. M. &
F. D. Rauch. 1989b. The influence of treatment combinations on areca palm
seed germination. Hawaii Nursery Research. Univ. of Hawai'i Res. Ext. Series
103:22-23.
Yoshii, C. M.,
F. D. Rauch & C. I. Okazaki. 1989. Treatments influencing the germination
of bamboo palm seeds. Hawaii Nursery Research. Univ. of Hawai'i Pres. Ext.
Series 103:23-24.
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