The Palmaceae comprise a very large family of woody trees, erect shrubs and climbers within about 225 genera. Palmae and Arecaceae are alternative names for Palmaceae. The Palmaceae provide very many useful products including edible nuts (e.g. Cocos nucifera L., coconut), edible fruits (e.g. Phoenix dactylifera L., date palm), oils (e.g. Elaeis guineensis Jacq., oilpalm), starch (e.g. Metroxylon sagus Rottb., sago palm), and many other useful products - such as construction materials (e.g. Calamus spp., rattans). The fruits are nuts, berries or drupes and usually indehiscent.
Until recently seed storage behaviour was assumed to be recalcitrant throughout the Palmaceae, but it is now known that this classification was mistaken. Whilst it is possible that some species may ultimately be proven to show recalcitrant seed storage behaviour, for most species seed storage behaviour is expected to be orthodox. For the present seeds of Cocos spp. should be treated as recalcitrant; further investigations are required to clarify seed storage behaviour in these species.
SEED DORMANCY AND GERMINATION
The seeds vary considerably in size and include the largest seed known to man (Lodoicea maldivica (Gmel.) Pers., double coconut). The embryos are comparatively small and are surrounded by substantial endosperm (liquid endosperm in Cocos) and a hard, woody husk; germination is hypogeal.
Dormancy varies considerably between the species. For example, dormancy is substantial in Elaeis spp. but less so in Cocos spp. where seed development and germination may be continuous. It is, however, difficult to germinate seeds of most members of the Palmaceae. The main problem is the time taken by the seeds to germinate: in field or glasshouse sowings the germination of some individuals within an accession takes more than a year. Seedling development also occurs comparatively slowly. Thus embryo culture (for propagation) or the excised embryo test (to estimate viability) - see Chapter 11, Volume I - may be preferable in some cases to attempting to germinate the seeds. Treatments to the seed covering structures, pre-soaking in water (or possibly gibberellins) and constant temperatures of 25°C or 30°C or an alternating temperature of about 20°/30°C (12h/12h) are generally promotory (although some exceptions to the above are noted in this chapter).
Detailed information on seed germination and dormancy is provided in this chapter for the genera Areca (including synonyms within Chrysalidocarpus), Cocos, Elaeis (including synonyms within Corozo), and Phoenix. In addition a summary of information on germination test procedures and/or germination test periods for very many other palms is provided. It will be seen that, unless special treatments are applied, considerable germination test periods are required for many of these species; it is hoped that the provision of this information will help to ensure that germination tests are not concluded too soon.
Seed germination in Palmaceae
Acanthophoenix rubra (Bory) Wendl.
In glasshouse sowings 71d may elapse before the seeds start to germinate (12,13).
Acoelorraphe pimo [Erythea pimo]
In glasshouse sowings 193d may elapse before the seeds start to germinate (12, 13).
Acoelorraphe Wrightii (Gris. & Wendl.) Wendl. ex Becc.
Seeds from which pericarps have been removed begin to germinate after 6m (1), but the delay is only 3m if the seeds are tested in moist sand in an alternating temperature regime of 20°/30°C (night/day) (8). It is suggested that pericarp removal and the latter regime be used as a general procedure for germinating seeds of Acoelorraphe spp.
Acrocomia aculeata
Pre-soaking for 7d followed by warm stratification at 39°C for 80d, with a subsequent germination test at 27°C was not a successful dormancy-breaking treatment (19) - despite the suitability of this procedure for seeds of other palms.
Acrocomia crispa
The seeds are difficult to germinate, but the following is a partly successful dormancy-breaking treatment: remove exocarp and mesocarp, crack endocarp and then pre-soak the seeds for 12 to 24h (7).
Acrocomia mexicana
The seeds are very difficult to germinate. Seeds from which endocarps have been removed start to germinate after 183d whilst for whole seeds the delay is 440d (11).
Acrocomia sclerocarpa Mart.
The seeds are very difficult to germinate. Seeds from which endocarps have been removed take a year before they start to germinate whilst for whole seeds the delay can be 2.5 years (11).
Acrocomia spp.
Filing and scarification are partly successful dormancy-breaking treatments (12, 13), but the following procedure is more successful: pre-dry at 65° to 71°C for 2 to 3w, then germinate in moist sand in a glasshouse with a fluctuating temperature regime where the maximum temperature is 50°C (12, 13).
Actinorhytis calapparia Wendl. & Drude
In glasshouse sowings 2 to 2.5m may elapse before the seeds start to germinate (11, 15).
Aiphanes acanthophylla (Mart.) Burret
There is a delay of 43 to 90d before the seeds start to germinate in moist sand at 20°/30°C (8, 11).
Aiphanes caryotaefolia
In glasshouse sowings 60 to 70d may elapse before the first seeds germinate (11).
Aiphanes erosa [Martinezia erosa Lind.]
Untreated seeds begin to germinate after 58 to 110d (11). Pre-soaking the seeds for 7d followed by warm stratification at 35°C for 80d with subsequent transfer to room temperature for the germination test is a partly successful dormancy-breaking treatment (19).
Allagoptera campestre
In glasshouse sowings 2m may elapse before the first seeds germinate (11).
Archontophoenix alexandrae (F. Muell.) Wendl. & Drude
The following procedures are partly successful dormancy-breaking treatments for seeds of the Alexandra palm: pre-soak the seeds for 3d, then test for germination in an alternating temperature regime of 20°/26°C for 7w (17); scarify the seeds by hand and then either pre-soak in water or 1000 ppm gibberellic acid for 3d (17); pre-treat the seeds with 1000 ppm gibberellic acid for 3d (18); test for germination at constant temperatures of 25°C, 30°C, or 35°C (21, 24). The following are successful dormancy-breaking procedures: testa removal (17); constant temperatures between 24° and 28°C (3); an alternating temperature regime of 20°/30°C (8); pre-treat with gibberellic acid at 10 or 100 ppm for 3d (18); pre-treat with gibberellic acid at 1000 ppm for 3d (17).
Archontophoenix cunninghamiana (Wendl.) Wendl. & Drude
There is a delay of 90 to 100d before the seeds start to germinate (8, 11), and the optimum constant temperatures for germination are between 24° and 28°C (3).
Archontophoenix spp.
As a general procedure it is suggested that testa be removed from over the embryos, the seeds pre-treated in 100 ppm gibberellic acid for 3d and subsequently tested for germination at 25°C or 30°C.
Areca spp. - see separate section
Arecastrum romanzoffianum (Cham.) Becc.
[Cocos romanzoffianum Cham.; Cocos plumosa Hook.]
The seeds are very difficult to germinate (3, 8, 19). Pre-soaking for 7d followed by warm stratification at 39°C for 80d, with a subsequent germination test at 27°C was not a successful dormancy-breaking treatment (19) - despite the suitability of this procedure for seeds of other palms. Testing for germination in a peat/perlite medium at 24° to 28°C (3) or in moist sand at 20°/30°C (8) have, however, been reported as partly successful dormancy-breaking treatments.
Arenga caudata
Pre-soak the seeds for several days and then test for germination at 27°C - the first seeds begin to germinate after 65d (12, 13).
Arenga engleri Becc.
The seeds are very dormant (6, 7, 8, 11) and between 4 and 21m may elapse before the seeds start to germinate in glasshouse sowings (11). Scarifying the seeds in concentrated sulphuric acid for 5 or 20 min does not promote germination (7), but the following scarification procedures may be promotory: scarifying the mesocarp at the hilum with sandpaper (7); scarifying the mesocarp at the hilum with sandpaper and subsequently pre-soaking the seeds (7); or scarifying the mesocarp at the hilum with sandpaper and then scarifying the seeds in concentrated sulphuric acid for 10 min (7). Alternatively whole seeds can be tested for germination in moist sand in an alternating temperature regime of 20°/30°C for a year (8).
Arenga microcarpa Becc.
In glasshouse sowings 9m may elapse before the seeds start to germinate (11).
Arenga obtusifolia Mart.
In glasshouse sowings between 8 and 12m may elapse before the seeds start to germinate (11).
Arenga pinnata (Wurmb.) Merr. [A. saccharifera Labill.]
The seeds of the sugar palm (or gomuti palm) are difficult to germinate (8, 19) and there can be a 6m delay before the seeds start to germinate in glasshouse sowings (8, 11). Testing the seeds for germination in moist sand at 20°/30°C (8), or at 27°C after first pre-soaking for 7d and then giving a warm stratification treatment at 39°C for 80d (19) promotes the germination of some, but not all, dormant seeds.
Arenga tremula (Blanco) Becc.
There can be a delay of between 103 and 175d before the seeds start to germinate (8, 11). Testing in moist sand at 20°/30°C is only partly-successful in promoting the germination of dormant seeds (8).
Arenga undulatifolia
In glasshouse sowings 9m may elapse before the seeds start to germinate (11).
Arenga Wightii
The seeds are difficult to germinate (11, 19) and 10m may elapse before the seeds start to germinate in glasshouse sowings (11). Pre-soaking the seeds for 7d followed by warm stratification at 39°C for 80d and subsequently testing for germination at 27°C promotes the germination of some, but not all, dormant seeds (19).
Arikuryoba schizophylla
In glasshouse sowings between 51 and 107d may elapse before the seeds start to germinate (11).
Astrocaryum aculeatum G.F.W. Mey
The seeds are very difficult to germinate and may take 3 or more years to germinate in glasshouse sowings (11).
Astrocaryum mexicanum [Hexopetion mexicanum]
The seeds germinate readily in glasshouse sowings, beginning within 38 days (12, 13).
Astrocaryum standleyanum
The seeds take between 50 and 150d before they start to germinate in glasshouse sowings (11, 12, 13). The germination test procedure used is to pre-soak the seeds for several days and then test at a constant temperature of 27°C (12, 13).
Astrocaryum vulgare Mart.
The seeds are difficult to germinate and between 11 and 14m may elapse before they start to germinate in glasshouse sowings (11).
Astrocaryum spp.
Pre-drying the seeds for 2 to 3w at between 65° and 71°C with subsequent germination tests in an alternating temperature environment where the maximum temperature reaches 50°C is reported to promote germination (12, 13).
Attalea cohune [Orbignya cohune Mart.]
The seeds show considerable dormancy (6) and there is a delay of between 2 and 6m before they begin to germinate in glasshouse sowings (11, 12, 13).
Bactris gasipaes HBK [Guilielma gasipaes (HBK) Bailey]
In glasshouse sowings the seeds begin to germinate after 69d (11).
Bactris major Jacq.
In glasshouse sowings the seeds begin to germinate after 6m (11).
Bactris monostachya
The seeds germinate fully during a 3m test at 24° to 28°C (3).
Bactris ottostapfeana
The seeds can be germinated by testing at 27°C after pre-soaking for several days (12, 13).
Bactris rhaphidacantha
In glasshouse sowings there is a delay of 6 to 7m before the seeds start to germinate (11).
Bentinckia condapanna
The seeds can be germinated by testing at 27°C after pre-soaking for several days (12, 13).
Bentinckia nicobarica Becc.
In glasshouse sowings between 74 and 85d may elapse before the seeds start to germinate (11).
Bismarckia nobilis
The seeds can be germinated by testing at 27°C after first pre-soaking the seeds for several days (12, 13).
Borassus flabellifer L.
Seeds of the Palmira palm are difficult to germinate (11, 19) and untreated seeds may require more than 260d before they begin to germinate in glasshouse sowings (11). Moist sand or peat/perlite (1:1) are suitable media for germination (3,26). The germination of some, but not all, dormant seeds can be promoted by pre-soaking for 7d followed by warm stratification at 39°C for 80d and then testing at 27°C (19), but testing whole fruits in a peat/perlite medium (1:1) at 24° to 28°C for 5m is reported to result in full germination (3).
Brahea bella Bailey
The germination of some, but not all, dormant seeds can be promoted by testing in moist sand at 20°/30°C (8).
Brassiophoenix drymophloeoides
In glasshouse sowings 8m may elapse before the seeds start to germinate (11).
Butia bonnetii Becc.
The seeds are very difficult to germinate (8). The germination of some, but not all, can be promoted by testing in moist sand at 20°/30°C for 300d (8).
Butia capitata (Mart.) Becc.
The seeds are very difficult to germinate (8) due to extremely severe dormancy (24) - untreated seeds germinate between 28 and 960d after sowing (8, 11). Gibberellic acid pre-applied for 1h at concentrations between 100 and 2000 ppm can be promotory (24).
Butia eriospatha
The seeds are very difficult to germinate; between 8 and 22m may elapse before they begin to germinate in glasshouse sowings (11).
Butia yatay (Mart.) Becc.
The seeds are very difficult to germinate and, when tested in moist sand at 20°/30°C, take between 2 and 20m to germinate (8).
Calamus spp.
Seeds of the rattans are difficult to germinate and between 107 and 408d may elapse before they begin to germinate in glasshouse sowings (11). The germination of some, but not all, dormant seeds can be promoted by testing whole fruits in a peat/perlite (1:1) medium at 24° to 28°C (3).
Calyptrocalyx spicatus Blume
The seeds are reported to germinate readily in glasshouse sowings (11).
Carpentaria acuminata
In glasshouse sowings the seeds begin to germinate after 78d (11).
Caryota cumingii Lodd.
In glasshouse sowings the seeds begin to germinate after between 114 and 317d (11, 12, 13).
Caryota mitis Lour.
The seeds are difficult to germinate (3,8,11,14,22) and may require 5 to 6m before they begin to germinate (8,11,15,22). The germination of some, but not all, dormant seeds can be promoted by: removing the endocarps and testing in a peat/perlite (1:1) medium at 24° to 28°C (3); testing in moist sand at 20°/30°C (8); testing in vermiculite at 25°C or 30°C (22); or by pre-soaking the seeds for 7d followed by warm stratification at 39°C for 80d with subsequent testing at 27°C (19).
Caryota urens L.
Seeds of the fish-tail, or toddy, palm are difficult to germinate (3,8,11) and may require between 6 and 7m before they begin to germinate either in glasshouse sowings (11) or at 20°/30°C in moist sand (8).
Chamaedorea cataractarum
In glasshouse sowings there can be a delay of 82d before the seeds begin to germinate (11).
Chamaedorea costaricana
In glasshouse sowings 41d may elapse before the seeds begin to germinate (11).
Chamaedorea elatior
In glasshouse sowings 118d may elapse before the seeds begin to germinate (11).
Chamaedorea elegans Mart. [Collinia elegans Liebm.; Neanthe bella O.F. Cook]
The seeds of the parlor palm are difficult to germinate: the first seeds begin to germinate after 4m (with full germination after 10m) in moist sand at 20°/30°C (8). Whole fruits or seeds can be successfully tested for germination: in a peat/perlite medium (1:1) at 24° to 28°C (3); in moist sand or vermiculite at 30°C (24); or in moist sand at 20°/30°C (8).
Chamaedorea erumpens E.H. Moore
The seeds are difficult to germinate and may be delayed for 7m before they begin to germinate (8, 11, 12, 13). Whole fruits or seeds can be successfully tested for germination in a peat/perlite medium (1:1) at 24° to 28°C (3).
Chamaedorea glaucifolia
In glasshouse sowings 8m may elapse before the seeds begin to germinate (11). Pre-soaking the seeds for several days with subsequent testing at 27°C can at least partly promote germination (12, 13).
Chamaedorea humilis
Whole fruits or seeds can be successfully tested for germination in a peat/perlite (1:1) medium at 24° to 28°C (3).
Chamaedorea metallica
In glasshouse sowings there can be a delay of 197d before the seeds begin to germinate (11).
Chamaedorea microspadix Burret
The seeds begin to germinate after between 50 and 100d in test (8, 11). The germination of some, but not all, dormant seeds can be promoted by testing in moist sand at 20°/30°C (8).
Chamaedorea monostachys
In glasshouse sowings the seeds begin to germinate after 5m in test (11).
Chamaedorea oblongata Mart.
The seeds are difficult to germinate (8, 11) and begin to germinate after 40d in glasshouse sowings (11). When tested in moist sand at 20°/30°C the seeds germinate after between 187 and 237d (8).
Chamaedorea oreophila
The seeds are difficult to germinate and begin to germinate after 7m in glasshouse sowings (11).
Chamaedorea seifrizii Burret
The seeds are very difficult to germinate (8, 11) and begin to germinate after 8m in moist sand at 20°/30°C (8).
Chamaedorea tenella Wendl.
The seeds take between 3 and 4m to germinate in moist sand at 20°/30°C (8).
Chamaedorea tepejilote
The seeds are reported to germinate readily (11).
Chamaerops humilis L. var humilis
In glasshouse sowings the seeds begin to germinate after 3m (11). In moist sand at 20°/30°C the seeds take between 4 and 6m to germinate (8).
Chamaerops humilis L. var arborescens
In glasshouse sowings 2m may elapse before the seeds begin to germinate (11).
Chrysalidocarpus lutescens - see Areca section
Clinostigma gronophyllum
In glasshouse sowings 4m may elapse before the seeds begin to germinate (11).
Clinostigma ponapensis H.E. Moore
The seeds begin to germinate after 2.5 to 3.5m in moist sand at 20°/30°C (8). The germination of some, but not all, dormant seeds can be promoted by pre-soaking for several days and then testing at 27°C (12, 13).
Coccothrinax acuminata
In glasshouse sowings there can be a delay of 7w before the seeds begin to germinate (11).
Coccothrinax alta
In glasshouse sowings there can be a delay of 9w before the seeds begin to germinate (11).
Coccothrinax argentata (Jacq.) Bailey [C. argentea Auth.; C. jucunda Sarg.; C. garberi Sarg.; Palma argentata Jacq.]
The seeds are very difficult to germinate and germinate after between 7 and 9m in moist sand at 20°/30°C (8).
Coccothrinax crinita Becc.
The seeds begin to germinate after 3.5 to 6m (8, 11).
Coccothrinax fragrans
The seeds begin to germinate after 45 to 240d (11, 12, 13).
Coccothrinax martii (Gris. & Wendl.) Becc.
The seeds begin to germinate after 47 to 101d (8, 11).
Coccothrinax miraguama (HBK) Becc.
The seeds begin to germinate after 60 to 104d (8, 12, 13).
Coccothrinax pseudorigida
The seeds begin to germinate after 48d (12, 13).
Cocos nucifera - see Cocos section
Cocos plumosa, Cocos romanzoffianum
- see Arecastrum romanzoffianum
Collinia elegans - see Chamaedorea elegans
Copernicia alba Morong
The seeds begin to germinate after 3m in moist sand at 20°/30°C (8).
Copernicia australis Becc.
The germination of some, but not all, dormant seeds can be promoted by testing seeds in aerated water (changed daily) after either no pre-treatment or after scarifying the seeds in 10% sulphuric acid for 15 min (10). Full germination, however, can be achieved by hand scarification near the embryo and then testing in aerated water, or by first pre-soaking for 9m in aerated water and then scarifying the seeds by hand near the embryo (10).
Copernicia burretiana
In glasshouse sowings the seeds begin to germinate after 37d (12, 13).
Copernicia cerifera (Arr.) Mart. [C. prunifera]
In the glasshouse untreated seeds of the Carnauba wax palm begin to germinate 2m after sowing (11). Full germination has been achieved by pre-soaking the seeds for 7d followed by warm stratification at 35°C for 80d and then testing for germination at 27°C (19).
Copernicia cowellii
In glasshouse sowings the seeds begin to germinate after 37d (12, 13).
Copernicia gigas
In glasshouse sowings the seeds begin to germinate after 73d (12, 13).
Copernicia glabrescens Wendl. ex Becc.
The seeds germinate after between 1 and 3m in test (8, 11). Germination can be at least partly promoted by pre-soaking for several days and then testing at 27°C (12, 13).
Copernicia hospita
In glasshouse sowings the seeds begin to germinate after between 1 and 4m (11, 12, 13).
Copernicia macroglossa Wendl. ex Becc.
The seeds germinate after between 70 and 88d in moist sand at 20°/30°C (8).
Copernicia pauciflora
In glasshouse sowings there can be a delay of 33d before the seeds begin to germinate (11).
Copernicia torreana, Copernicia vespertilionum
The seeds are reported to germinate readily (12, 13).
Copernicia yarey
In glasshouse sowings the seeds begin to germinate after 4m (11).
Copernicia spp.
Testing the seeds in aerated water (changed daily) until the first seeds germinate promotes the germination of some dormant seeds - the duration of pre-soaking treatment required varying from 2d for freshly harvested seeds to several weeks for older seeds (10).
Corozo oleifera (HBK) Bailey - see also Elaeis section
The seeds are very difficult to germinate and take a year before they begin to germinate in glasshouse sowings (11).
Corypha elata Roxb.
Seeds of the gebang palm germinate readily - beginning within 20d - when tested in moist sand after pericarp removal (1).
Corypha lecomtei
In glasshouse sowings the seeds begin to germinate after 3m (11).
Corypha umbraculifera L.
Seeds of the talipot palm begin to germinate after 52 to 226d in test (11,12,13,15).
Cryosophila Warscewiczii
In glasshouse sowings the seeds begin to germinate after 68d (11).
Cyrtostachys lakka Becc.
The seeds germinate within 2 to 3m in moist sand at 20°/30°C (8).
Cyrtostachys renda Blume
In glasshouse sowings the seeds begin to germinate after 4m (11).
Deckenia nobilis Wendl.
The seeds are difficult to germinate and only begin to germinate 8m after sowing in the glasshouse (11).
Desmoncus horridus
In glasshouse sowings the seeds begin to germinate after 5m (11).
Dictyosperma album (Bory.) Wendl. & Drude ex Scheff.
The seeds begin to germinate 1 to 3m after sowing (1,3,8,11,12,13). Whole ripe fruits or seeds can be successfully tested for germination in a peat/perlite (1:1) medium at 24° to 28°C (3).
Dictyosperma aureum (Balf. f.) Nich.
The seeds begin to germinate 54 to 102d after sowing (8,11,12,13).
Dictyosperma furfuraceum - see Syagrus comosa
Diplothemium maritimum
After pre-soaking for several days the seeds begin to germinate 73d after sowing in tests at 27°C (12,13).
Drymophloeus Beguinii
The seeds begin to germinate 26 to 45d after sowing in the glasshouse (11,12,13).
Drymophloeus olivaeformis (Giseke) Miq.
The seeds begin to germinate after 4m in glasshouse sowings (11) and in moist sand at 20°/30°C (8).
Elaeis spp. - see separate section and Coroza oleifera
Erythea armata Wats. [E. Roezlii Lind.]
Seeds of the big blue hesper palm begin to germinate after 5 to 6m in glasshouse sowings (11) and in moist sand at 20°/30°C (8).
Erythea Brandegeeis Purpus
Seeds of the San José hesper palm are difficult to germinate and only begin to germinate 10 to 13m after glasshouse sowings (11). Germination can be at least partly promoted by pre-soaking the seeds for several days and then testing at 27°C (12,13).
Erythea edulis (Wendl.) Wats.
Seeds of the Guadalupe palm begin to germinate after 2.5m in glasshouse sowings (11) and within 6m when tested in moist sand at 20°/30°C (8).
Erythea pimo - see Acoelorraphe pimo
Eugeissona tristis Griff.
Whole fruits begin to germinate 5m after sowing whereas the seeds begin to germinate 7m after sowing (11,15).
Euterpe edulis Mart.
Germination is slow - between 6 and 11w may elapse before the seeds begin to germinate (11) - due to thick, hard mesocarps and endocarps (16). The germination of some, but not all, dormant seeds can be promoted by: mesocarp removal (16); mesocarp removal followed by pre-soaking at 30°C for 3d (16); a 2h ultrasonic treatment at 50 to 60 Hz and 80 W followed by pre-washing for 42h (16); scarification for 10 min in concentrated sulphuric acid followed by pre-soaking at 30°C for 2d (16). But the most successful dormancy-breaking treatment reported is to soak in a 6% hydrogen peroxide solution for 2d after removing the mesocarps from the seeds (16).
Euterpe longibracteata
In glasshouse sowings the seeds begin to germinate after 24d (12,13). Non-dormant seeds can be germinated between moist paper towels at 38°C (16).
Gastrococos crispa [G. armentalis]
In glasshouse sowings between 2 and 4m may elapse before the seeds start to germinate (11).
Gaussia attenuata (O.F. Cook) Becc.
The seeds germinate between 1 and 9m after sowing (8,11,12,13).
Geonoma baculifera
In glasshouse sowings 7m may elapse before the seeds start to germinate (11).
Geonoma congesta
In glasshouse sowings 6m may elapse before the seeds start to germinate (11).
Geonoma longipetiolata
In glasshouse sowings between 2.5 and 4m may elapse before the seeds start to germinate (12,13).
Geonoma longisecta
In glasshouse sowings 9m may elapse before the seeds start to germinate (11).
Geonoma membranacea
In glasshouse sowings fresh and dry seeds begin to germinate after 48d and 141d respectively (11).
Guilielma gasipaes - see Bactris gasipaes
Hedyscepe canterburyana
The seeds are difficult to germinate: whole fruits or seeds begin to germinate after 6 to 7m at 24°/28°C (3).
Heterospathe coriacea
In glasshouse sowings between 2.5 and 7.5m may elapse before the seeds start to germinate (11).
Heterospathe minor
In glasshouse sowings 2m may elapse before the seeds start to germinate (11).
Hexopetion mexicanum - see Astrocaryum mexicanum
Howea Belmoreana Becc. [Kentia Belmoreana F. Muell.]
Whole fruits or seeds can show a delay of between 40 and 223d before they start to germinate (1,3,8).
Howea Forsteriana Becc. [Kentia Forsteriana F. Muell.]
At 24° to 28°C or at 20°/30°C whole fruits or seeds can show a delay of between 2.5 and 8m before they germinate (3,8).
Hyophorbe indica
In glasshouse sowings 75d may elapse before the seeds start to germinate (12,13).
Hyphaene crinita
In glasshouse sowings 72d may elapse before the seeds start to germinate (11).
Hyphaene schatan
In glasshouse sowings 38d may elapse before the seeds start to germinate (11).
Hyphaene thebaica (L.) Mart.
In glasshouse sowings between 2 and 3m may elapse before seeds of the doum, or dum, palm start to germinate (11).
Hyphaene turbinata
In glasshouse sowings 5m may elapse before the seeds start to germinate (11).
Iguanura wallichiana (Mart.) Benth. & HBK.f.ex Becc.
There can be a delay of 11w before the seeds start to germinate (15).
Jessenia bataua
In glasshouse sowings 67d may elapse before the seeds start to germinate (11).
Jubaea chilensis (Molina) Baill.
There can be a delay of 3 to 4m before the seeds start to germinate (8,12,13).
Kentia Belmoreana - see Howea Belmoreana
Kentia Forsteriana - see Howea Forsteriana
Kentiopsis olivaeformis
In glasshouse sowings 317d may elapse before the seeds start to germinate (11).
Latania loddigesii Mart.
There can be a delay of 54 to 70d before the seeds start to germinate (1,8,11).
Latania lontaroides
In glasshouse sowings 100d may elapse before the seeds start to germinate (11).
Latania verschaffeltii Lam.
The seeds should be pre-soaked for several days and then tested for germination at 27°C (12,13).
Licuala amplifrons Miq.
There can be a delay of 70d before the seeds start to germinate in glasshouse sowings (12,13).
Licuala elegans
In glasshouse sowings 74d may elapse before the seeds start to germinate (11).
Licuala glabra Griff.
There can be a delay of 4w before the seeds start to germinate (15).
Licuala gracilis
In glasshouse sowings there can be a one year delay before the seeds start to germinate (11).
Licuala grandis Wendl.
There can be a delay of between 53 and 166d before the seeds start to germinate (1,8,11,12,13).
Licuala lauterbachii
In glasshouse sowings 7m may elapse before the seeds start to germinate (11).
Licuala Muelleri
In glasshouse sowings 4m may elapse before the seeds start to germinate (11).
Licuala Peltata Roxb.
The seeds may take between 3 and 13m to germinate (8,11).
Licuala spinosa Thunb.
Between 2.5 and 16m may be required before untreated seeds germinate (1,8,11), but germination can be promoted by pre-soaking the seeds for several days and then testing at 27°C or 20°/30°C (8,12,13).
Livistona Australis (R. Brown) Mart.
Although there can be a delay of 3 to 4m before the seeds start to germinate (8,11), whole ripe fruits tested in a peat/perlite (1:1) medium at 24° to 28°C are reported to germinate readily (3).
Livistona chinensis (Jacq.) R. Brown & Mart.
The seeds germinate readily, beginning within 1m of sowing (1,8,11,19): full germination has been achieved by testing in moist sand at 25°C, 30°C, 20°/30°C or 25°/30°C (8,20,24,28).
Livistona colchinchinensis (Blume) Mart. [L. hoogendorpii; L. saribus (Lour.) Cheval.]
The seeds begin to germinate within 1m of sowing in the glasshouse (12,13).
Livistona decipiens Becc.
There can be a delay of between 1 and 8m before the seeds germinate (1,8,11).
Livistona humilis
In glasshouse sowings 48d may elapse before the seeds start to germinate (11).
Livistona Jenkinsiana Griff.
In glasshouse sowings 4m may elapse before the seeds start to germinate (11).
Livistona Kingiana Becc.
There can be a delay of 77d before the seeds start to germinate (15).
Livistona Mariae F.W. Muell.
Removal of the exocarps from the seeds with subsequent testing at 27°C can promote full germination (14).
Livistona Muelleri Hort.
In glasshouse sowings 4m may elapse before the seeds start to germinate (11).
Livistona Robinsoniana Becc.
There can be a delay of between 4 and 6m before the seeds start to germinate (8,11).
Livistona rotundifolia (Lam.) Mart. [L. altissima Zoll.]
There can be a delay of between 45 and 199d before the seeds germinate (1,8,11).
Livistona speciosa Kurz
There can be a delay of 9w before the seeds start to germinate (15).
Martinezia erosa - see Aiphanes erosa
Mascarena lagenicaulis Bailey
There can be a delay of between 2 and 8m before the seeds germinate (8,11).
Mascarena verschaffeltii (Wendl.) Bailey
There can be a delay of between 74 and 93d before the seeds germinate (8,11). An optimum temperature for germination of 35°C has been reported (23,24).
Mauritia flexuosa L. f.
There can be a delay of between 5 and 7m before the seeds germinate (8,11).
Microcoelum weddellianum (Wendl.) H.E. Moore
There can be a delay of between 3 and 6m before the seeds start to germinate (8,11), even when tested in an alternating temperature regime of 20°/30°C (8). Pre-soaking the seeds for several days followed by testing at 27°C can at least partly promote germination (12,13).
Nannorhopa ritchiana
The following treatments were not successful in promoting the germination of dormant seeds: pre-soaking for 9 or 16d (9); pre-soaking for 2d and then dipping the seeds in boiling water for 2 min (9); scarification of the seeds with concentrated sulphuric acid for 5 or 10 min (9); scarification of the seeds by hand (9). Testing in moist sand in an alternating temperature regime of 30°/39°C (9h/15h), however, was a partly-successful dormancy-breaking treatment (9).
Neanthe bella - see Chamaedorea elegans
Nenga pumila (Mart.) Wendl.
The seeds begin to germinate after 70d in test (15).
Neodypsis decaryi Jum.
The seeds begin to germinate after 2m in glasshouse sowings (11) or in moist sand at 20°/30°C (8).
Oenocarpus panamanus Bailey
There can be a delay of between 25 and 70d before the seeds germinate (8,11).
Oncosperma fasciculatum Thwaites
After first pre-soaking for several days, the seeds begin to germinate after 46d in test at 27°C (12,13).
Oncosperma horridum (Griff.) Scheff.
There can be a delay of 200d before the seeds start to germinate (15).
Oncosperma tigillarium Ridley
After first pre-soaking for several days, the seeds begin to germinate after 44d at 27°C (12,13).
Opsiandra maya O.F. Cook
There can be a delay of between 26 and 99d before the seeds germinate (8,11).
Orania appendiculata
In glasshouse sowings 7m may elapse before the seeds start to germinate (11).
Orania sylvicola (Griff.) Moore
There can be a delay of 70d before the seeds start to germinate (15).
Orbignya cohune see Attalea cohune
Orbignya phalerata
There can be a delay of 71d before the seeds start to germinate (12,13).
Orbignya speciosa
Dormant seeds of the babasu palm can be germinated by removing part of the endocarp and then pre-soaking the seeds for 10d before sowing (5).
Orbignya spp.
The seeds can show considerable dormancy (6) and may show a delay of 6m before they start to germinate (11). It is suggested that they be treated as described for O. speciosa (above) and then tested for germination at 30°C.
Oreodoxa oleracea Mart. [Roystonea oleracea O.F. Cook]
Pre-soaking seeds of the cabbage palm, or palmiste, for 7d followed by warm stratification at 35°C for 80d did not promote germination in tests at 27°C (19).
Oreodoxa regia HBK [Roystonea regia O.F. Cook]
Seeds of the royal, or cuban, palm can be dried to 7.9% moisture content and subsequently rehydrated and germinated (25). There can be a delay of between 21 and 142d before fresh seeds germinate (1,3,8,11). The optimum temperature for germination is reported to be 30°C (22,24). Full germination has been achieved using the following (alternative) procedures: mesocarp removal with testing between moist paper towels at 30°C (25); testing in sand at 25°/30°C in light, 24h/d, for 37d (28); testing whole ripe fruits or seeds in a peat/perlite (1:1) medium at between 24° and 28°C (3); or pre-chilling at 10°C for 2m, with subsequent testing for germination at 30°C (4).
Palma argentata - see Coccothrinax argentata
Phoenicophorium Borsigianum (Koch) Wendl.
In glasshouse sowings there can be a delay of between 21 and 124d before the seeds start to germinate (11).
Phoenix spp. - see separate section
Phytelephas macrocarpa Ruiz & Pav.
In glasshouse sowings there can be a delay of between 6 and 12m before seeds of the ivory-nut palm germinate (11).
Pinanga insignis
There can be a delay of 77d before the seeds germinate (15).
Pinanga kuhlii Blume
There can be a delay of between 36 and 79d before the seeds germinate (8,11). The seeds can be germinated at 27°C after pre-soaking for 7d followed by warm stratification at 35°C for 80d (19).
Pinanga malaiana (Mart.) Scheff.
There can be a delay of 4 to 6m before the seeds start to germinate with germination being complete 9m after sowing (15).
Pritchardia Hillebrandii
In glasshouse sowings there can be a delay of 40d before the seeds start to germinate (11).
Pritchardia Kaalae Rock
Embryos can be excised and cultured in a modified Vacin & Went medium (6).
Pritchardia lowreyana
There can be a delay of 45d before the seeds start to germinate (15).
Pritchardia minor
There can be a delay of 2m before the seeds start to germinate (15).
Pritchardia pacifica
In glasshouse sowings there can be a delay of between 44 and 77d before the seeds start to germinate (11).
Pritchardia thurstonii F. Muell. & Drude
The seeds begin to germinate after 4m in moist sand at 20°/30°C (8).
Pseudophoenix Sargentii Wendl. ex Sarg.
The seeds show orthodox seed storage behaviour - germinating after 2 years' dry storage (29) - and can be very dormant, with fresh seeds failing to germinate (29). There can be a delay of 5m before the seeds start to germinate in moist sand at 20°/30°C (8). Endocarp removal with subsequent testing for germination at 29.5°C can promote full germination (29), but testing the seeds in regimes where the temperature for part of the day is below 29.5°C can substantially reduce the proportion of seeds which germinate (29).
Pseudophoenix vinifera (Martens) Becc.
The seeds show othodox seed storage behaviour - germinating after 2 years' dry storage (29) - and can be very dormant, with fresh seeds failing to germinate (29). There can be a delay of between 23 and 178d before the seeds start to germinate in glasshouse sowings (11,12,13). The germination of at least some, but not necessarily all, dormant seeds can be promoted by pre-soaking for several days before testing at 27°C (12,13). Endocarp removal with subsequent testing for germination at 29.5°C can promote full germination (29), but testing the seeds in regimes where the temperature for part of the day is below 29.5°C can substantially reduce the proportion of seeds which germinate (29).
Ptychandra glauca Scheff.
In glasshouse sowings there can be a delay of 49d before the seeds start to germinate (11).
Ptychococcus paradoxus Becc.
In glasshouse sowings there can be a delay of 6m before the seeds start to germinate (11).
Ptychosperma angustifolium
In glasshouse sowings there can be a delay of 5m before the seeds start to germinate (11). The germination of at least some, but not necessarily all, dormant seeds can be promoted by pre-soaking for several days before testing at 27°C (12,13).
Ptychosperma elegans (R. Brown) Blume
The seeds start to germinate about 2m after sowing (1). Full germination has been achieved by testing in moist sand at 20°/30°C (8).
Ptychosperma hosinoi H.E. Moore
There can be a delay of 72d before the seeds start to germinate (8). Pre-soaking for several days and then testing at 27°C can promote germination (12, 13).
Ptychosperma hospitum Bur.
In glasshouse sowings 2m may elapse before the seeds start to germinate (11).
Ptychosperma ledermannianum
If first pre-soaked for several days, the seeds begin to germinate after 2m in test at 27°C (12, 13).
Ptychosperma Macarthurii (Wendl.) Nichols
Seeds of the Macarthur palm begin to germinate 2 to 2.5m after sowing (1,8). Optimum germination test temperatures of 27°C (17), or 25°C, 30°C, and 35°C (21,24) have been reported but germination was not complete in these regimes. Full germination was achieved at 27°C after either pre-soaking the seeds for 3d or pre-treating in 1000 ppm gibberellic acid for 3d (17).
Ptychosperma Nicolai
In glasshouse sowings 3m may elapse before the seeds start to germinate (11).
Ptychosperma propinquum (Becc.) Becc. ex Martelli
When tested in moist sand at 20°/30°C there can be a delay of 5m before the seeds start to germinate (8).
Reinhardtia gracilis (Wendl.) Drude ex Damm.
The seeds begin to germinate after 2.5m in moist sand at 20°/30°C (8).
Rhaphia gracilis Becc. [R. palma-pinus (Gaertn.) Hutch.; R. gaertneri Becc.]
If pre-soaked for several days the seeds start to germinate after 4m in test at 27°C (12, 13).
Rhaphia pedunculata Beauv. [R. farinifera (Gaertn.) Hylander; R. monbuttorum Drude; R. ruffia (Jacq.) Mart.]
There can be a delay of 81d before the seeds start to germinate in glasshouse sowings (12, 13).
Rhapidophyllum hystrix (Pursh.) Wendl. & Drude
The seeds germinate after between 73 and 96d in moist sand at 20°/30°C (8).
Rhapis excelsa (Thunb.) Henry [R. flabelliformis Ait.]
Full germination was achieved within a 5m test in moist sand at 20°/30°C (8).
Rhapis humilis Blume
The seeds germinate after between 3 and 4m in moist sand at 20°/30°C (8).
Rhopalostylis sapida Wendl. & Drude
The seeds start to germinate 2 to 2.5m after sowing (8,12,13).
Rhyticocos amara
The seeds start to germinate 2m after sowing (12,13).
Roystonea oleracea - see Oreodoxa oleracea
Roystonea regia - see Oreodoxa regia
Sabal bermudana Bailey
The seeds germinate between 88 and 137d after sowing (8,11).
Sabal blackburniana
The seeds germinate between 99 and 120d after sowing (1,11).
Sabal causiarum (O.F. Cook) Becc.
The seeds germinate between 43 and 131d after sowing (8,11).
Sabal domingensis
In glasshouse sowings 48d may elapse before the seeds start to germinate (11).
Sabal glaucescens
The seeds start to germinate 2m after sowing in the glasshouse (12,13).
Sabal jamaicensis
In glasshouse sowings 37d may elapse before the seeds start to germinate (11).
Sabal mexicana
There can be a delay of between 48 and 120d before the seeds start to germinate (1,11).
Sabal minor (Jacq.) Pers.
The seeds show considerable dormancy and require 7 or 24m to after-ripen at room temperature or 3° to 5°C respectively (20). There can be a delay of 4m before the seeds start to germinate (8,11). Germination can be promoted partly by 100 ppm gibberellic acid (20). A constant temperature of 25°C has been reported as the optimum germination test temperature (20,24).
Sabal palmetto (Walt.) Lodd.
There can be a delay of 3 or 4m before the seeds start to germinate (8, 11). Optimum germination test temperatures - in moist sand - are 25°C or 30°C (20,24).
Sabal parviflora Becc.
There can be a delay of between 22 and 42d before the seeds start to germinate (8, 11).
Sabal peregrina
In glasshouse sowings 7w may elapse before the seeds start to germinate (11).
Sabal texana (O.F. Cook) Becc.
There can be a delay of between 70 and 169d before the seeds germinate (8, 11).
Sabal yapa C.H. Wright ex Becc.
There can be a delay of between 82 and 220d before the seeds germinate (8, 11).
Salacca conferta Griff.
There can be a delay of between 1 and 6m before the seeds germinate (11, 15).
Salacca edulis Reiw.
There can be a delay of 3m before the seeds start to germinate in moist sand at 20°/30°C (8). Pre-soaking for several days before testing at 27°C can at least partly promote germination (12, 13).
Salacca rumphii Wall.
The seeds are reported to germinate readily (12, 13, 15), and full germination has been achieved in tests at 27°C after first pre-soaking the seeds for several days (12, 13).
Satakentia liukiuensis (Hatusima) H.E. Moore
There can be a delay of between 70 and 112d before the seeds germinate (8, 11).
Scheelea Leandroana
In glasshouse sowings 5m may elapse before the seeds start to germinate (11).
Scheelea phalerata
The seeds are very difficult to germinate and 466d may elapse before the seeds start to germinate (11).
Scheelea preussii
In glasshouse sowings between 3 and 10m may elapse before the seeds start to germinate (11).
Serenoa repens (Bartr.) Small
There can be a delay of 3.5m before seeds tested in moist sand at 20°/30°C begin to germinate (8).
Siphokentia Beguinii
In glasshouse sowings 3.5m may elapse before the seeds start to germinate (11).
Socratea durissima Wendl.
In glasshouse sowings 4.5m may elapse before the seeds start to germinate (11), but pre-soaking the seeds for several days before testing at 27°C can at least partly promote germination (12, 13).
Socratea exorhiza
In glasshouse sowings 4m may elapse before the seeds start to germinate (11).
Syagrus campestris
In glasshouse sowings 4.5m may elapse before the seeds start to germinate (11).
Syagrus campicola
There can be a delay of 10m before the seeds start to germinate (12, 13).
Syagrus comosa [Dictyosperma furfuraceum]
There can be a delay of between 3 and 10m before the seeds start to germinate (12, 13).
Syagrus coronata (Mart.) Becc.
There can be a delay of 3.5m before seeds start to germinate in moist sand at 20°/30°C (8).
Syagrus quinquefaria, Syagrus sancona
In glasshouse sowings between 2 and 2.5m may elapse before the seeds start to germinate (11).
Syagrus weddelliana
Full germination has been achieved by testing whole fruits in a peat/perlite medium (1:1) at 24° to 28°C (3).
Thrinax argentea
The promotion of germination of some, but not all, dormant seeds can be achieved by pre-soaking the seeds for 7d followed by warm stratification at 35°C for 80d and then testing at 27°C (19).
Thrinax barbadensis
It is reported that the seeds germinate readily (1).
Thrinax exmanii
There can be a delay of 99d before the seeds start to germinate in glasshouse sowings (12, 13).
Thrinax microcarpa Sarg.
There can be a delay of 3m before the seeds start to germinate in moist sand at 20°/30°C (8).
Thrinax Morrisii
In glasshouse sowings between 2 and 6m may elapse before the seeds start to germinate (11).
Thrinax parviflora Swartz
There can be a delay of 3 to 4m before the seeds start to germinate (1,8).
Trachycarpus excelsa Wendl.
The seeds germinate readily in moist sand at 25°C (21,24) or 20°/30°C (8).
Trachycarpus fortunei Wendl.
The seeds are more difficult to germinate than T. excelsa (above), and there can be a delay of between 2 and 3m before the seeds start to germinate (8,11,21,24). Optimum germination test temperatures of 25°C or 30°C have been reported (21,24), but do not result in full germination.
Trithrinax acanthocoma
In glasshouse sowings 2.5m may elapse before the seeds start to germinate (11).
Veitchia arecina
In glasshouse sowings 6w may elapse before the seeds start to germinate (11).
Veitchia Joannis Wendl.
There can be a delay of between 1 and 3m before the seeds start to germinate in glasshouse sowings (11,12,13). Embryo excision and culture in a modified Vacin & Went medium is a successful test regime (6).
Veitchia merillii (Becc.) H.E. Moore
There can be a delay of 1 to 2m before the seeds start to germinate (8,11) although when tested in sand at 25°-30°C in light, 24h/d, germination is reported to be completed within 57d (28).
Veitchia montgomeryana H.E. Moore
There can be a delay of 1 to 3m before the seeds start to germinate (8,11).
Veitchia Winin H.E. Moore
There can be a delay of 1 to 2m before the seeds start to germinate (8,11).
Verschaffeltia splendida Wendl.
The seeds germinate readily and completely within 1 to 2m in glasshouse sowings (11) and in moist sand at 20°/30°C (8).
Wallichia caryotoides
There can be a delay of between 3 and 6m before the seeds start to germinate in glasshouse sowings (11,12,13).
Washingtonia filifera (L. Lind.) Wendl.
The seeds begin to germinate after 17d in moist sand at 20°/30°C (8).
Washingtonia robusta Wendl.
The seeds germinate fully within 3m at 24° to 28°C (3) or 20°/30°C (8).
Zombia antillarum (Desc. ex Jacq.) Bailey
There is a delay of between 6 and 21w before the seeds germinate (8,11,12,13).
References
1. Basu, S.K. and Mukherjee, D.P. (1972). Studies on the germination of palm seeds. Principes, 16, 136-137.
2. Bovi, M.L.A. and Cardoso, M. (1978). [A preliminary report on conservation of seeds of hearts of palm.] Bragantia, 37, 65-71.
3. Bunker, E.J. (1975). Germinating palm seeds. Combined Proceedings of the International Plant Propagator's Society, 25, 377-378.
4. Campbell, G.K. (1982). Seed germination following mild chilling in Royal Palm (Roystonea regia). South African Journal of Botany, 1, 79.
5. Gehlsen, C.A. (1937). Observaçoes sobre o babassu (Orbignya speciosa) e sua germinação - a germinação da oiticia. Boletim da secretaria de Agricultura Industria e commercio de Pernambuco, 2, 428-433.
6. Hodel, D. (1977). Notes on embryo culture of palms. Principes, 21, 103-108.
7. Holmquist, J. De D. and Popenoe, J. (1967). Germination experiments. The effect of scarification on the germination of seed of Acrocomia Crispa and Arenga engleri. Principes, 11, 23-25.
8. Ishihata, K. (1974). [Studies on the morphology and cultivation of palms. On the germination of seed in ornamental palms.] Bulletin of the Faculty of Agriculture, Kagoshima University, 24, 11-23.
9. Khattak, G.M. (1962). Seed germination of dwarf palm (Nannorhops ritchiana). Pakistan Journal of Forestry, 12, 202-204.
10. Kitzke, E.D. (1958). A method for germinating Copernicia palm seeds. Principes, 2, 5-8.
11. Koebernik, J. (1971). Germination of palm seed. Principes, 15, 134-137.
12. Loomis, H.F. (1958). The preparation and germination of palm seeds. Principes, 2, 98-102.
13. Loomis, H.F. (1961). Culture of the palms. Preparation and germination of palm seeds. American Horticultural Magazine, 40, 128-130.
14. Lothian, T.R.N. (1959). Further notes concerning the central Australian cabbage palm (Livistona Mariae). Principes, 3, 53-63.
15. Manokaran, N. (1979). Germination of Malaysian palms. Malaysian Forester, 42, 50-52.
16. Mullett, J.H., Beardsell, D.V. and King, H.M. (1981). The effect of seed treatment on the germination and early growth of Euterpe edulis (family Palmae). Scientia Horticulturae, 15, 239-244.
17. Nagao, M.A., Kanegawa, K. and Sakai, W.S. (1980). Accelerating palm seed germination with gibberellic acid, scarification, and bottom heat. HortScience, 15, 200-201.
18. Nagao, M.A. and Sakai, W.S. (1979). Effect of growth regulators on seed germination of Archontophoenix alexandrae. HortScience, 14, 182-183.
19. Rees, W.A. (1963). Germination of palm seeds using a method developed for the oil palm. Principes, 7, 27-30.
20. Sento, T. (1970). [Studies on the germination of seed of the palms. II. Livistona chinensis (R. Brown), Phoenix roebelenii (O'Brien) and Sabal species.] Journal of the Japanese Society for Horticultural Science, 39, 261-268.
21. Sento, T. (1971). [Studies on the germination of seed of the palms. III. Archontophoenix alexandrae (Wendl. & Drude), Ptychosperma macarthurii (Wendl.) and Trachycarpus species.] Journal of the Japanese Society for Horticultural Science, 40, 246-254.
22. Sento, T. (1971). [Studies on the germination of seed of the palms. IV. Areca catechu (Linn.), Caryota mitis (Lour.) and Roystonea regia (O.F. Cook).] Journal of the Japanese Society for Horticultural Science, 40, 255-261.
23. Sento, T. (1972). [Studies on the seed germination of palms. V. On Chrysalidocarpus lutescens, Mascarena verschaffeltii and Phoenix dactylifera.] Journal of the Japanese Society for Horticultural Science, 41, 76-82.
24. Sento, T. (1976). [Studies on the germination of palm seeds.] Memoirs of the College of Agriculture, Echime University, 21, 1-78.
25. Soetisna, U. (1981). Approaches to the conservation of seeds which have previously been difficult to store, with special reference to lime (Citrus aurantifolia (Christm.) Swing.) and royal palm (Oreodoxa regia HBK). Ph.D. thesis, University of Reading.
26. Veerasamy, S. (1982). Polyembryomy and twin seedlings in Borassus flabellifer L. (Palmae). Botanical Journal of the Linnean Society, 85, 147-152.
27. Yocum, H.G. (1964). Factors affecting the germination of palm seeds. American Horticultural Magazine, 43, 104-106.
28. Chin, H.F., Hor, Y.L. and Mohd Lassim, M.B. (1984). Identification of recalcitrant seeds. Seed Science and Technology, 12, 429-436.
29. Read, R.W. (1968). A study of Pseudophoenix (Palmae). Gentes Herbarum, 10, 169-213.
ARECA
|
A. Aliciae |
|
|
A. catechu L. [A. cathecu L.] |
areca, betel palm |
|
A. concinna |
|
|
A. langloisiana |
|
|
A. latiloba |
|
|
A. lutescens Boryl [A. madagascariensis;
Chrysalidocarpus lutescens (Boryl) Wendl.] |
Madagascar palm |
|
A. triandra |
|
I. Evidence of dormancy
Seeds of Areca spp. may be dormant (4,6), exhibiting poor and delayed germination (1,3,8,10). See the comment for a note on seed storage behaviour.
II. Germination regimes for non-dormant seeds
-
III. Unsuccessful dormancy-breaking treatments
A. catechu
Constant temperatures: 40°C (17)
Pre-dry: 3-12d, in shade (14)
Sodium azide: pre-applied, 24h, 10-3, 10-4 M (4)
Sodium ethylenediaminetetraacetate: pre-applied, 24h, 10-3, 10-4 M (4)
2-2'-Dipyridyl: pre-applied, 24h, 10-3, 10-4 M (4)
8-Hydroxyquinine: pre-applied, 24h, 10-3, 10-4 M (4)
8-Hydroxyquinoline: pre-applied, 24h, 10-3, 10-4 M (4)
A. lutescens
Constant temperatures: 14°C, 40°C (18)
Removal of seed covering structures: pericarp (3); exocarp, then pre-soak, 24,72h (15)
A. madagascariensis, A. triandra
Pre-soak: 7d, then warm stratification, 35°C, 80d, germinate at 27°C (16)
IV. Partly-successful dormancy-breaking treatments
A. catechu
Constant temperatures: 31°-35°C (6); 25°C, 30°C, 35°C (17)
Pre-soak: 24h (4); then pre-dry, 3-12d (14)
Removal of seed covering structures: pericarp (3); pericarp, germinate at 20°/30°C (8)
2,4-Dinitrophenol: pre-applied, 24h, 10-4 M (4) Pectinase: pre-applied, 24h (5)
A. lutescens
Constant temperatures: 25°C, 30°C, 35°C (18)
Pre-soak: 7d, then warm stratification, 39.5°C, 80d, germinate at 27°C (16)
Removal of seed covering structures: exocarp, then GA, pre-applied, 72h, 100-1000 ppm, germinate at 20°-22°C in daylight, 60d (15)
Areca spp.
Pre-soak: 7d, then warm stratification, 39.5°C, 80d, germinate at 27°C (16)
V. Successful dormancy-breaking treatments
A. catechu
Constant temperatures: 24°C (6)
Pre-soak: (11, 12)
Removal of seed covering structures: pericarp, then pre-wash, then pre-dry, 24h (1)
2,4-Dinitrophenol: pre-applied, 24h, 10-3 M (4)
A. concinna, A. latiloba
Pre-soak: (11,12)
A. lutescens
Constant temperatures: 30°C (2)
Alternating temperatures: 20°/30°C (8)
Removal of seed covering structures: pericarp, then pre-wash, then pre-dry, 24h (1); pericarp, then pre-wash, germinate at 20°/30°C (8)
Pre-soak: (11,12)
A. triandra
Removal of seed covering structures: pericarp, then pre-wash, then pre-dry, 24h (1)
VI. Comment
Sand, peat mixed with perlite, and vermiculite are reported to be suitable germination test media (1,3,4,11,12,15,17,18). When sown in moist sand, the calix (top end of the nut) should be pointing up and level with the surface of the sand (9). The germination of seeds of A. catechu is quite sensitive to temperature: at 30°C and above germination is reduced (6,17,18); at 20°C dormancy is reported to be induced (6); the optimum constant temperature for germination is reported to be 25°C (6,17,18). Alternating temperatures may be more suitable than constant temperature germination test regimes since germination is reported to be better in glasshouse sowings than at constant temperatures (12). Despite the reported induction of dormancy at 20°C, a period of warm stratification at this temperature can be promotory (6).
Pre-drying, though widely practised, is an ineffective dormancy-breaking treatment (9,14). We are uncertain, however, whether Areca spp. show orthodox or recalcitrant seed storage behaviour: we are aware that air-dry storage is practised in India and have received assurances that Areca spp. show orthodox storage characteristics, but several publications report damage to the seeds as the result of desiccation (2,7). It remains our suspicion that, despite apparently contradictory evidence, Areca spp. are possibly orthodox.
The most effective dormancy-breaking treatments appear to be removal of the pericarp combined with pre-soaking in water (1,3,8,11,12) or gibberellins (15). Accordingly it is suggested that the pericarps be removed from the seeds and then GA3 be pre-applied at 1000 ppm for 72 hours and the seeds then tested at 25°C, or possibly 20°/30°C. Germination is slow: allow at least 41 days for A. Aliciae (10); A. catechu may require 55 (10), 71 (11), 90 (1), 103 (6) or 120 days (9) to germinate; A. concinna 43 (11) to 61 days (10); A. langloisiana 114 days (10); A. latiloba 27 (11) to 70 days (13); A. lutescens 31 (11), 120 (16) or 135 days (8); and A. triandra 41 (10,11) to 120 days (16).
VII. References
1. Basu, S.K. and Mukherjee, D.P. (1972). Studies on the germination of palm seeds. Principes, 16, 136-137.
2. Becwar, M.R., Stanwood, P.C. and Roos, E.E. (1982). Dehydration effects on imbibitional leakage from desiccation-sensitive seeds. Plant Physiology, 69, 1132-1135.
3. Bunker, E.J. (1976). Germinating palm seeds. Combined Proceedings of the International Plant Propagators' Society, 25, 377-378.
4. Das, N.K. (1977). Physiology of arecanut (Areca catechu Linn.) germination. V. Studies on the effect of pre-treatment of seednuts with certain respiratory inhibitors on sprouting. Seed Research, 5, 184-186.
5. Das, N.K. and Baruah, H.K. (1974). Physiology of arecanut (Areca catechu L.) germination. III. Effect of pectinase enzyme extract on sprouting of seednuts and growth of seedling. Journal of Plantation Crops, 2, 10-13. (From Horticultural Abstracts, 1975, 45, 7847.)
6. Das, N.K. and Ray, A.K. (1980). Certain dormancy and viability studies in arecanuts (Areca catechu). Preprint 17, 19th International Seed Testing Association Congress 1980, Vienna.
7. Guppy, H.B. (1912). Studies in Seeds and Fruits, Williams and Norgate, London.
8. Ishihata, K. (1974). [Studies on the morphology and cultivation of palms. On the germination of seed in ornamental palms.] Bulletin of the Faculty of Agriculture, Kagoshima University, 24, 11-23.
9. Khandige, S.B. (1956). The influence of drying on the germination of seed arecanuts (Areca catechu L.). Madras Agricultural Journal, 43, 3-6.
10. Koebernik, J. (1971). Germination of palm seed. Principes, 15, 134-137.
11. Loomis, H.F. (1958). The preparation and germination of palm seeds. Principes, 2, 98-102.
12. Loomis, H.F. (1961). Culture of the palms. Preparation and germination of palm seeds. American Horticultural Magazine, 40, 128-130.
13. Manokaran, N. (1979). Germination of Malaysian palms. Malaysian Forester, 42, 50-51.
14. Parameswar, N.S. (1962). Germination of seed arecanuts (Areca catechu L.). Science and Culture, 28, 135-136.
15. Rauch, F.D., Schmidt, L. and Murakami, P.K. (1983). Seed propagation of palms. Combined Proceedings of the International Plant Propagators Society, 32, 341-347.
16. Rees, A.R. (1963). Germination of palm seeds using a method developed for the oil palm. Principes, 7, 27-30.
17. Sento, T. (1971). [Studies on the germination of seed of the palms. IV. On the Areca catechu (Linn.), Caryota mitis (Lour.) and Roystonea regia (O.F. Cook).] Journal of the Japanese Society for Horticultural Science, 40, 255-261.
18. Sento, T. (1972). [Studies on the seed germination of palms. V. On Chrysalidocarpus lutescens, Mascarena verschaffeltii and Phoenix dactylifera.] Journal of the Japanese Society for Horticultural Science, 41, 76-82.
COCOS
|
C. nucifera L. var aurea Hort. |
|
|
C. nucifera L. var nana (Griff.) Nar. |
dwarf coconut |
|
C. nucifera L. var typica Nar. |
tall coconut |
I. Evidence of dormancy
Delayed germination of seeds of C. nucifera var aurea and most C. nucifera var typica is a common problem for growers and breeders (1, 18). Seeds of C. nucifera var nana, and those from C. nucifera var typica grown in Peninsular Malaysia and on the Pacific Coast of Panama, however, germinate more readily (10), and may germinate viviparously (19). But seednuts of Makapuno type fruits, where the endosperm is not liquid but solid, reportedly never germinate (9): germination can only be achieved in this type of fruit by embryo culture (9). Both immature and overmature (little or no liquid endosperm remaining) fruits show delayed germination (2, 10, 15), but storage of mature fruits for 2 to 4 months promotes germination and reduces the subsequent time taken to germinate (16).
II. Germination regimes for non-dormant seeds
C. nucifera
Constant temperatures: 30°-35°C (17)
Alternating temperatures: 20°/30°C (11)
III. Unsuccessful dormancy-breaking treatments
C. nucifera var typica
Removal of seed covering structures: mosecarp (7); part of mesocarp, apical end (7); parts of mesocarp, apical and basal ends (18); part of mesocarp, near base, then 2,4-dichlorophenoxyacetic acid, pre-applied, 24h, 150, 200 ppm (6)
IV. Partly-successful dormancy-breaking treatments
C. nucifera var typica
Constant temperatures: 30°C, 107d (17)
Removal of seed covering structures: part of mesocarp, near base, then 2,4-dichlorophenoxyacetic acid, pre-applied, 24h, 150 ppm, plus 10 ml, 5 ppm, injected into kernel (6)
V. Successful dormancy-breaking treatments
C. nucifera var aurea
Alternating temperatures: 20°/30°C (11)
C. nucifera var typica
Constant temperatures: 35°C (17)
Alternating temperatures: 20°/30°C (11)
Pre-soak: (10); 7d (2); 14d (4, 18)
Removal of seed covering structures: part of mesocarp, near base (6, 13); excise embryo, culture in White's medium (1, 5, 9)
Potassium nitrate: pre-applied, 48h, 10-2, 2x10-2 M (18)
Sodium carbonate: pre-applied, 48h, 10-2, 2x10-2 M (18)
Magnesium sulphate: co-applied, 11500, 23000 ppm injected into mesocarp (3)
Copper sulphate: co-applied, 5500, 11000 ppm injected into mesocarp (3)
Manganese sulphate: co-applied, 4250, 8500 ppm injected into mesocarp (3)
Ferric sulphate: co-applied, 3750, 7500 ppm injected into mesocarp (3)
Zinc sulphate: co-applied, 6500, 13000 ppm injected into mesocarp (3)
Ammonium molybdate: co-applied, 50, 100 ppm injected into mesocarp (3)
Sodium borate: co-applied, 5750, 11500 ppm injected into mesocarp (3)
VI. Comment
Until further investigations have clarified seed storage behaviour, coconut must remain classified as probably recalcitrant. Seed dormancy in coconut has been reviewed elsewhere (5, 18). In view of their large size it is unlikely that the fruits will be tested for germination in laboratory tests. The following procedure has been proposed for germinating whole coconut fruits in nursery sowings: place the seednuts close together in a moist sandy soil (6, 11, 17) in full sun, either with the fruits' broadest face down (7, 13) or - in the case of spherical fruits - on their end with the calyx uppermost, and irrigate frequently with an overhead sprinkler (10). The most suitable constant temperatures for germination in nursery sowings are between 30° and 35°C (17), but alternating temperatures, roughly 20°/30°C, are reported to be more effective in promoting germination (11, 14). The duration of the germination test should be at least 100 days for those varieties which germinate more readily, and 150 days for the slower germinating varieties (10). Pre-treatments to the seednuts will probably be required. A 1 to 2 week pre-soak is probably the most effective method of promoting germination (2, 4, 10, 18) - particularly where the fruit has dried (2). The removal of part of the mesocarp at the base of the fruits above the eyes also promotes germination, but if this is done it is essential that the fruits be prevented from drying throughout the subsequent germination test.
Extraction of the embryo from the fruits with subsequent embryo culture is required for laboratory germination tests. Embryo culture has been achieved in a variety of combinations of media (1,5,9), including coconut milk alone (9). The most favoured combination appears to be White's major elements plus vitamins, plus Nitsch's trace elements, plus sucrose, plus coconut milk (1). This has the following composition: 100 ml of White's major elements (50 ppm Ca, 72 ppm Mg, 70 ppm Na, 65 ppm K, 47 ppm N - as nitrate, 4 ppm P - as phosphate, 140 ppm S - as sulphate, 31 ppm Cl, 1 ppm Fe - as ferric citrate, 1.67 ppm Mn, 0.005 ppm Cu, 0.59 ppm Zn, 0.26 ppm B, 0.001 Mo), 1 ml of Nitsch's trace elements (3 ppm managanese sulphate, 0.5 ppm zinc sulphate, 0.025 ppm copper sulphate, 0.5 ppm boric acid, 0.025 ppm sodium molybdate) but also including 25 ppm of cobalt chloride, 4 ml of a 0.25% solution of ferric citrate, 5 ml of White's vitamins (0.57 ppm I, 0.1 ppm thiamin, 0.5 ppm nicotinic acid, 0.1 ppm pyridoxine, 3 ppm glycine, 20000 ppm sucrose) with the addition of 50 ppm calcium pantothenate and 2 ml of a 0.1% solution of indoleacetic acid in alcohol; it is then made up to 1 litre with double distilled water and 0.2g casein hydrolysate, 8g agar, and 20g sucrose added; after autoclaving and subsequent cooling 2 litres of coconut milk are added, the solution mixed, and then left overnight (1). Germination and growth have occurred at temperatures between 15° to 28°C (1) - but it is expected that germination will be most rapid at the higher temperatures. A greater proportion of embryos germinate in light than in dark (9). Germination can be quite rapid - 2 to 4 weeks - but subsequent growth can be very slow (9).
VII. References
1. Abraham, A. and Thomas, K.J. (1962). A note on the in vitro culture of excised coconut embryos. Indian Coconut Journal, 15, 84-88.
2. Aiyadurai, S.G. (1956). Observation on germination of dry seed coconuts. Madras Agricultural Journal, 43, 464-466.
3. Amma, B.S. (1964). Preliminary studies on the effect of micronutrients on the germination of coconut seednuts. Current Science, 33, 49-50.
4. Child, R. (1974). Coconuts. 335 pp. Longmans, London.
5. Cutter, V.M. Jr. and Wilson, K.S. (1954). Effect of coconut endosperm and their growth stimulants upon the development in vitro of embryos of Cocos nucifera. Botanical Gazette, 115, 234-240.
6. Deshpande, B.R. and Kulkarni, V.G. (1962). Studies in germination of coconut. Part I. Coconut Bulletin, 16, 336-338, 343.
7. Espino, R.B. (1923). On the germination of coconuts. Philippine Agriculturist, 11, 191-200.
8. George, M.K. (1964). Off season seed coconuts, will they yield quality seedlings. Coconut Bulletin, 18, 13-15.
9. Guzman, E.V. De and Del Rosario, D.A. (1964). The growth and development of Cocos nucifera L. Makapuno embryo in vitro. Philippine Agriculturist, 48, 82-84.
10. Harries, H.C. (1981). Germination and taxonomy of the coconut. Annals of Botany, 48, 873-883.
11. Ishihata, K. (1974). [Studies on the morphology and cultivation of palms. On the germination of seed in ornamental palms.] Bulletin of the Faculty of Agriculture, Kagoshima University, 24, 11-23.
12. Kartha, S. (1981). Embryo of coconut and its germination. Journal of Plantation Crops, 9, 125-127.
13. Kenman, E.T. (1973). Effect of seednut trimming on the germination and growth of coconuts. Papua New Guinea Agricultural Journal, 24, 26-29.
14. Loomis, H.F. (1961). Culture of the palms. Preparation and germination of palm seeds. American Horticultural Magazine, 40, 128-130.
15. Marar, M.M.K. and Varma, R. (1958). Coconut nursery studies. Effect of maturity of seednuts on germination and vigour of seedlings. Indian Coconut Journal, 11, 81-86.
16. Nampoothiri, K.U.K., Mathew, J. and Sukumaran, C.K. (1974). Variation in germination pattern of coconut cultivars and hybrids. Journal of Plantation Crops, 1, 24-27.
17. Sento, T. (1974). [Studies on the seed germination of palms. VI. On Cocos nucifera L., Phoenix humilis Royle var. hanceana Becc. and Phoenix sylvestris Roxb.] Journal of the Japanese Society for Horticultural Science, 42, 380-388.
18. Thomas, K.M. (1974). Influence of certain physical and chemical treatments on the germination and subsequent growth of coconut Cocos nucifera L. seedlings: A preliminary study. East African Agricultural and Forestry Journal, 40, 152-156.
19. Whitehead, R.A.W. (1965). Speed of germination, a characteristic of possible taxonomic significance in Cocos nucifera L. Tropical Agriculture, Trinidad, 42, 369-372.
ELAEIS
|
E. guineensis Jacq. [E. madagascariensis
Becc.] |
oil palm |
|
E. guineensis Jacq. x E. oleifera (HBK)
Cortés |
|
|
E. oleifera (HBK) Cortés [E. melanococca
Gaertn.; Corozo oleifera (HBK) Bailey] |
American oil palm |
I. Evidence of dormancy
E. guineensis, E. oleifera and the hybrid E. guineensis x E. oleifera show pronounced dormancy which is a substantial problem for planters and breeders (1,2,4,6,7,9-15,19,20,22,24,29,30). Within E. guineensis pisifera oil palms are reported to be more difficult to germinate than dura or tenera oil palms (3,9,19,30). The seed covering structures (pericarp, endocarp and the operculum - testa and endosperm over embryo) are the main cause of problems when attempting to germinate seeds of oil palm (11, 12). According to some reports excised oil palm embryos are not dormant (11,12), but in other reports embryo dormancy has been detected (22). After-ripening for 2 months at room temperature can result in the loss of embryo dormancy (22), but note that after-ripening of whole seeds is not effective in avoiding the problems caused by the seed covering structures.
In preparing seeds for plantation sowings heat treatments of one sort or another are almost invariably applied. Here such treatments are described as pre-dry where the moisture content of the kernels is less than 16% (fresh-weight basis) for dura, less than 18% for oleifera, or less than 17% for tenera oil palms, but described as warm stratification where kernel moisture content is between 17 to 18% for dura, between 21 to 23% for tenera, or between 27 to 30% for pisifera oil palms. The latter values are the moisture contents of imbibed oil palm kernels. These values appear to be much lower than those for imbibed seeds of other species, but see the comment for information on embryo moisture contents.
II. Germination regimes for non-dornant seeds
-
III. Unsuccessful dormancy-breaking treatments
E. guineensis (dura)
Warm stratification: 44.5°C, 50-80d (24); 45°C, 40-50d (13); 50°C, 8-12d (13); 55°C, 4-8d (13); 60°C, 12h (13)
Pre-dry: 60°C, 1-4d (13); 39.5°C, 80d, germinate without additional moisture (23,24)
Pre-soak: 4h, then pre-dry, 20h, 4 cycles (7)
Removal of seed covering structures: pericarp, crack endocarp (26); excise embryo from dry seeds (21,22)
E. guineensis (dura x pisifera)
Pre-soak: (29)
GA3: pre-applied, 0.25, 0.5 ppm (29); pre-applied, 0.25, 0.5 ppm, then pre-dry, 40°C, 15d, then GA3, pre-applied, 0.25, 0.5 ppm (29); pre-applied, 0.25, 0.5 ppm, plus kinetin, pre-applied, 0.05, 0.1 ppm (29); pre-applied, 0.25, 0.5 ppm, plus kinetin, pre-applied, 0.05, 0.1 ppm, then pre-dry, 40°C, 15d, then GA3, pre-applied, 0.25, 0.5 ppm, plus kinetin, pre-applied, 0.05, 0.1 ppm (29)
Kinetin: pre-applied, 0.05, 0.1 ppm (29); pre-applied, 0.05, 0.1 ppm, then pre-dry, 40°C, 15d, then kinetin, pre-applied, 0.05, 0.1 ppm (29)
Ethephon: pre-applied, 1, 2 ppm (29); pre-applied, 1, 2 ppm, then pre-dry, 40°C, 15d, then ethephon, pre-applied, 1, 2 ppm (29); pre-applied, 1, 2 ppm, plus kinetin, pre-applied, 0.05, 0.1 ppm (29); pre-applied, 1, 2 ppm, plus kinetin, pre-applied, 0.05, 0.1 ppm, then pre-dry, 40°C, 15d, then ethephon, pre-applied, 1, 2 ppm, plus kinetin, pre-applied, 0.05, 0.1 ppm (29)
E. guineensis (tenera)
Constant temperatures: 40°C, in air or oxygen, 100% (12)
Pre-soak: 30°C, 5d, germinate at 25°-40°C, in air or oxygen, 100% (12)
Indoleacetic acid: pre-applied, 6h, 10 ppm, plus Vitamin B1, 100 ppm (10); pre-applied, 12h, 6 ppm, plus Vitamin B1, 60 ppm (10)
Removal of seed covering structures: endocarp, then pre-soak, 30°C, 5d, germinate at 25°-45°C in air or oxygen, 100% (11,12); endocarp, then pre-soak, 30°C, 5d, germinate at 30°C in oxygen, 20-100% (11,12); endocarp, then pre-soak, 30°C, 5d, germinate at 34°C in oxygen, 20-75% (11); endocarp, then pre-soak, 30°C, 5d, germinate at 34°C in oxygen, 0.2, 2 atmospheres (12); endocarp, then pre-soak, 30°C, 5d, then warm stratification, 28°-30°C, 4w, germinate at 30°C, 40°C (11,12); endocarp, then pre-soak, 30°C, 5d, then warm stratification, 30°C, in oxygen, 100%, 4w, germinate at 30°C in air or oxygen, 100% (12); endocarp, then pre-soak, 30°C, 5d, then warm stratification, 30°C, 42°C, 2m, germinate at 27°C (12); endocarp, then indoleacetic acid, pre-applied, 1h/d, 2w, 1-100 ppm (11); endocarp, then 2,4-dichlorophenoxyacetic acid, pre-applied, 1h/d, 2w, 1-100 ppm (11); endocarp, then ethylene chlorohydrin, pre-applied, 1h/d, 2w, 0.1, 1 ppm (11); operculum, then indoleacetic acid, pre-applied, 24h, 1-100 ppm (11)
E. guineensis
Pre-wash: 24d (14)
GA3: (4)
Hydrochloric acid: pre-applied, 7d, 5%, then pre-soak (5)
IV. Partly-successful dormancy-breaking treatments
E. guineensis (dura)
Warm stratification: 38°-40°C, 21,28d (27); 40°C, 20,40d (28); 45°C, 35d (13); 50°C, 6d (13); 60°C, 3,6h (13); 35°C, 38d, germinate at 25°/38°C (1d/7d or 1d/14d) (7)
Pre-dry: 40°C, 46-82d (13); 45°C, 22-46d (13); 50°C, 10-22d (13)
Pre-soak: then warm stratification, 39.5°C, 80d (23,24)
Removal of seed covering structures: pericarp (26); pericarp, then hydrochloric acid, pre-applied, 2d, 1% (26); endocarp (7); excise embryo (21)
Gamma irradiation: 1-100 K rad, then pre-soak (32); 1-140 K rad, after pre-soak (32)
E. guineensis (dura x pisifera)
Warm stratification: 38°C, 80, 100d (6)
Pre-dry: 38°C, 80,100d (6); 40°C, 30-60d (29)
GA3: pre-applied, 0.25, 0.5 ppm, then pre-dry, 40°C, 30-60d, then GA3, pre-applied, 0.25, 0.5 ppm (29); pre-applied, 0.25, 0.5 ppm, plus kinetin, pre-applied, 0.05, 0.1 ppm, then pre-dry, 40°C, 30-60d, then GA3 pre-applied, 0.25, 0.5 ppm, plus kinetin, pre-applied, 0.05, 0.1 ppm (29)
Kinetin: pre-applied, 0.05, 0.1 ppm, then pre-dry, 40°C, 30-60d, then kinetin, pre-applied, 0.05, 0.1 ppm (29)
Ethephon: pre-applied, 1, 2 ppm, then pre-dry, 40°C, 30-60d, then ethephon, pre-applied, 1, 2 ppm (29); pre-applied, 1, 2 ppm, plus kinetin, pre-applied, 0.05, 0.1 ppm, then pre-dry, 40°C, 30-60d, then ethephon, pre-applied, 1, 2 ppm, plus kinetin, pre-applied, 0.05, 0.1 ppm (29)
E. guineensis (pisifera)
Removal of seed covering structures: pericarp, then pre-soak, germinate at 39°-40°C (2)
E. guineensis (tenera)
Constant temperatures: 35°-40°C (10)
Alternating temperatures: 35°-40°C/room temperature (15d/11h) (10)
Warm stratification: 38°C, 5w, then 25°C, 2w, germinate at 38°C (12); 38°C, 5w, then 25°/38°C (1-3h/21-23h, 0.5-1.5d/5.5-6.5d) (12) Pre-soak: 25°C, 12h (10); 30°C, 5d, germinate at 40°C in air or oxygen, 100% (12)
Removal of seed covering structures: endocarp, then pre-soak, 30°C, 5d, germinate at 36°-42°C in oxygen, 20-100% (11, 12); endocarp, then pre-soak, 30°C, 5d, germinate at 38°C in oxygen, 1-1.75 atmospheres (11, 12); endocarp, then pre-soak, 30°C, 5d, germinate at 30°C in 100% oxygen/40°C in air (2.4h/21.6h, 6h/18h, 12h/12h, 18h/6h, 21.6h/2.4h) (11, 12); endocarp, then pre-soak, 30°C, 5d, then warm stratification, 30°C in air or oxygen, 100%, 4w, germinate at 28°C in oxygen, 100%, or 40°C in air or oxygen, 100% (11, 12); endocarp, then pre-soak, 30°C, 5d, then warm stratification, 40°C, 4w, germinate at 28°C in air or oxygen, 100%, or 40°C in air (11, 12); endocarp, then pre-soak, 30°C, 5d, then warm stratification, 40°C in oxygen, 100%, 4,8w, germinate at 30°C, 40°C in air or oxygen, 100% (11, 12)
E. guineensis
Warm stratification: (1)
Pre-soak: 4,8d, then remove pericarp (14); 45°C, 7d (5)
Ethephon: pre-applied, 2w, 10-2 M (4)
Hydrochloric acid: pre-applied, 7d, 1%, then pre-soak, 3d (5)
Removal of seed covering structures: pericarp, then pre-wash, 3-9d (14)
V. Successful dormancy-breaking treatments
E. guineensis (dura)
Warm stratification: 40°C, 30-80d (20); 40°C, 60,80d (28); 38°-40°C, 35-49d (27); 42°C, 60-80d (24); 38°C, 38d, germinate at 25°/38°C (1d/14d) (7)
Removal of seed covering structures: pericarp, then pre-soak, 25°C, 5-7d, pre-dry, 4-24h, then 39°C, 80d, then pre-soak, 1-3d, pre-dry, germinate at 22°-27°C (3,9,18,23,24); pericarp, then pre-soak, 25°C, 5-7d, then pre-dry, then warm stratification, 39°C, 80d, germinate at 22°-27°C (9,13,23,24,25); excise embryos after rehumidifying previously dried seeds, then culture (21,22)
E. guineensis (dura x pisifera)
Removal of seed covering structures: pericarp, then pre-soak, 25°C, 7d, then warm stratification, 39.5°C, 70d, then pre-soak, 7d (31)
E. guineensis (dura x tenera)
Removal of seed covering structures: pericarp, then pre-soak, 25°C, then pre-dry, 39.5°C, 60d (17)
E. guineensis (pisifera)
Removal of seed covering structures: epicarp and endocarp, then pre-soak, 24h, then remove operculum, germinate at 35°C (19)
E. guineensis (tenera)
Constant temperatures: 38°C, 9m (10); 40°C, in oxygen, 100%, 3m (11, 12)
Alternating temperatures: 38°C/room temperature (15d/1d) (10)
Warm stratification: 37°C, 2m, germinate at room temperature/37°C (1d/8d or 2d/15d) (10)
Removal of seed covering structures: pericarp, then pre-soak, 25°C, 5-7d, then pre-dry, 2-24h, then 39°C, 80d, then pre-soak, 1-3d, then pre-dry (3,9); pericarp, then pre-soak, 25°C, 5-7d, then pre-dry, then warm stratification, 39°C, 80d (9,25); operculum, germinate at 30°C (11); excise embryo, culture in White's medium (11,12)
E. guineensis
Alternating temperatures: 40°/27°C, 35°/25°C (day/night) (15); 25°/30°C, light, 24h/d, 42d, after heat treatment, 40°C, 60d (33)
Removal of seed covering structures: pericarp, then pre-wash, 11-32d, germinate for 32w (14); excise embryo, culture in Murashige and Skoog medium supplemented with 1 g 1-1 casein hydrolysate, 3 g 1-1 sucrose, 0.5 mg 1-1 indoleacetic acid, 0.1 mg 1-1 kinetin and 8 g 1-1 agar (8)
E. oleifera
Pre-dry: 39°C, 15d, then pre-soak, 43°C, 15 min, then warm stratification, 39°C, 65d (9)
VI. Comment
Despite widespread suggestions to the contrary seeds of Elaeis spp. show orthodox seed storage behaviour; for example, oil palm embryos which had been dried to 10.4% moisture content (fresh-weight basis) showed no loss in viability during 8 months storage at -196°C (8). There are two problems behind the mistaken classification of Elaeis spp. as recalcitrant. First, the embryos contain substantially more moisture than the average for whole kernels (8,21,22). For example, a typical moisture content of an imbibed kernel is about 21%, but embryos excised from such kernels contain roughly 48% moisture (8). When the kernels are dried to about 7% moisture content, embryo moisture contents are as high as 20-21% (8,22). Moreover equilibrium between kernel and embryo moisture contents is not established within 7 days at room temperature (8). Consequently it is not surprising that such embryos are killed by exposure to sub-zero temperatures (8). The second problem is, we believe, one of imbibition injury. Excised embryos dried to 20% moisture content and then cultured showed no loss in viability, whereas those embryos dried to 10.4% and subsequently cultured showed a 21% loss in viability (8). Similarly cultured embryos extracted from kernels dried below 15.3% moisture content show some development, but fail to produce seedlings whereas those from kernels at higher moisture contents do produce normal seedlings (21). Rehumidification of the dried kernels (15 days in a humid environment) before embryo excision and culture avoids this damage however (21,22), demonstrating that the damage to the dry embryos results from rapid imbibition, not from desiccation per se.
We believe there is a need to distinguish between those practices developed for the germination of seeds destined for large-scale sowings in plantations and those techniques required to promote the germination of oil palm seeds in tests to estimate the viability of accessions maintained in gene banks or to regenerate or multiply accessions. Most of the repeated soaking/drying treatments referred to in the preceding sections are intended to adjust kernel moisture contents to that best suited for germination - often assessed by the colour of the testae. This is necessary because subsequent germination is normally achieved in enclosed conical flasks, jars, polyethylene bags or similar vessels (11-13,17,18,20,23-25,29). Oil palm germination is very sensitive to either excess or inadequate moisture, and such procedures are very difficult to standardise. Consequently it is not recommended that gene banks should apply these techniques.
Whilst non-dormant seeds will germinate rapidly at around 25°C (3,9,10,13,17,20,23-25,27,31), dormant seeds require a higher constant temperature, around 39°C (2,7,9-12), and between 9 (10) and 12 months (7) at this temperature, but alternating temperatures are more effective in promoting germination than are constant temperatures (7,10-12,15). Until more definitive work has been completed a diurnal alternating temperature regime of 25°/35°C (8-12h/12-16h) would seem an appropriate, but temporary, recommendation.
Removal of some or all of the seed covering structures must be considered to be an essential component of oil palm germination tests intended to estimate viability in gene banks. Although embryo excision with subsequent culture for 4 weeks or so is likely to be successful (provided imbibition damage is avoided - see below), it does require both skill and time. We believe that the most appropriate treatment is to remove the operculum from imbided seeds (11,19): with experience it is reported to be possible to de-operculate 200 to 300 seeds per hour (19) and full germination should be achieved within 3 to 4 weeks in the germination test.
Whilst we envisage that the long-term storage of seed of Elaeis spp. under IBPGR preferred conditions (-20°C, with embryos at 5% moistur moisture content) is feasible, further investigations which recognise the potential problems of high embryo moisture contents and imbibition injury in these species would be advisable. The following germination test procedure is suggested. First humidify the dry embryos (or kernels) until embryo moisture content is at least 20% and preferably 40% (fresh weight basis). Then de-operculate the seed and test for germination on top of filter paper or between moist rolled paper towels at 25°/35°C (8-12h/12-16h) for at least 4 weeks. See reference (16) for a description of tetrazolium staining techniques for these species.
VII. References
1. Anonymous (1939). Oil palm seed germination. Bulletin of the Great Britain Imperial Institute, 37, 211-212.
2. Arasu, N.T. (1970). A note on the germination of Pisifera (shell-less) oil palm seeds. Malaysian Agricultural Journal, 47, 524-527
3. Comont, G. and Jacquemard, J.C. (1977). Germination des graines de palmier à huile (E. guineensis) en sacs de polyéthylène. Methodes par "chaleur sèche". Oléagineux, 32, 149-151.
4. Corley, R.H.V. (1976). Germination and seedling growth. In Oil palm Research (eds. R.H.V. Corley, J.J. Hardon and B.J. Wood), pp. 23-36, Elsevier, The Netherlands.
5. Curtler, E.A. (1926). Experiments on the germination of American oil palm seeds. Malayan Agricultural Journal, 14, 84-87.
6. Davidson, L. (1962). Dry heat method of oil palm germination. Planter, Kuala Lumpur, 38, 88-90.
7. Ferwerda, J.D. (1956). Germination of oil palm seeds. Tropical Agriculture, Trinidad, 33, 51-66.
8. Grout, B.W.W., Shelton, K. and Pritchard, H.W. (1983). Orthodox behaviour of oil palm seed and cryopreservation of the excised embryo for genetic conservation. Annals of Botany, 52, 381-384.
9. Hartley, C.W.S. (1977). The Oil Palm. 806 pp., Longman, London.
10. Henry, P. (1951). La germination des graine d'Elaeis. Revue Internationale de Botanique appliqueé et d'Agriculture Tropicale, 31, 565-591.
11. Hussey, G. (1958). An analysis of the factors controlling the germination of the seed of the oil palm Elaeis guineensis (Jacq.). Annals of Botany, 22, 259-284.
12. Hussey, G. (1959). The germination of oil palm seeds: experiments with Tenera nuts and kernels. Journal of the West African Institute for Oil palm Research, 2, 331-354.
13. Labro, M.F., Guénin, G. and Rabéchault, H. (1964). Essai de leveé de dormance des graines de palmier à huile (Elaeis guineensis Jacq.) par des temperatures elevées. Oléagineux, 19, 757-765.
14. Lucy, A.B. (1940). Experiments on the germination of oil palm seeds. Malayan Agricultural Journal, 28, 151-158.
15. Milsum, J.N. (1927). Hastening the germination of oil palm seeds. Malayan Agricultural Journal, 15, 82-84.
16. Mok, C.K. (1972). The tetrazolium test for evaluating the viability of oil palm (Elaeis guineensis Jacq.) seeds. Proceedings of the International Seed Testing Association, 37, 771-778.
17. Mok, C.K. and Hor, Y.L. (1977). The storage of oil palm (Elaeis guineensis) seed after high temperature treatment. Seed Science and Technology, 5, 499-508.
18. Ngui, M. and Ngim, K.S. (1982). An empirical modification to the method of germinating seeds in commercial oil palm seed production. 10 pp. Technical Bulletin No. 6, Department of Agriculture, Sabah, Malaysia.
19. Nwankwo, B.A. (1981). Facilitated germination of Elaeis guineensis var. pisifera seeds. Annals of Botany, 48, 251-254.
20. Odetola, A. (1974). Heat requirement of oil palm seeds for germination. Relation of seed age to heat requirement. Journal of the Nigerian Institute for Oil palm Research, 5, 79-84.
21. Rabéchault, H., Aheé, J. and Guénin, G. (1968). Recherches sur la culture "in vitro" des embryons de palmier à huile (Elaeis guineensis Jacq.). IV. Effets de la teneur en eau des noix et de la dureé de leur stockage. Oléagineux, 23, 233-237.
22. Rabéchault, H., Guénin, G. and Aheé, J. (1969). Recherches sur la culture "in vitro" des embryons de palmier à huile (Elaeis guineensis Jacq. var. dura Becc.) VI. Effets de la déshydratation naturelle et d'une réhydratation de noix dormantes et non dormantes. Oléagineux, 24, 263-268.
23. Rees, A.R. (1961). Effect of high-temperature pre-treatment on the germination of oil palm seed. Nature, 189, 74-75.
24. Rees, A.R. (1962). High-temperature pre-treatment and the germination of seed of the oil palm, Elaeis guineensis (Jacq.). Annals of Botany, 26, 569-581.
25. Rees, A.R. (1965). Some factors affecting the viability of oil palm seed in storage. Journal of the Nigerian Institute for Oil palm Research, 15, 317-324.
26. Savellano, N.S. (1955). Four methods of germinating African oil palm seeds. Philippine Agriculturist, 39, 535-539.
27. Tailliez, B. (1970). Germination accéléreé des graines de palmier à huile. Technique avec substrat. Oléagineux, 25, 335-336.
28. Trouslot, M.F., Guénin, G. and Rabéchault, H. (1967). Conservation et dormance des graines d'Elaeis guineensis Jacq. Oléagineux, Oléagineux, 22, 295-296.
29. Wan, C.K. and Hor, H.L. (1983). A study on the effects of certain growth substances on germination of oil palm (Elaeis guineensis Jacq.) seeds. Pertanika, 6, 45-48.
30. Wonkyi-Appiah, J.B. (1973). Germination of pisifera oil palm seeds under plantation conditions. Ghana Journal of Agricultural Science, 6, 223-226.
31. Wonkyi-Appiah, J.B. (1974). Effect of duration of heat treatment on germination of dura oil palm seed. Ghana Journal of Agricultural Science, 7, 57-59.
32. Wonkyi-Appiah, J.B. and Amuh, I.K.A. (1976). Preliminary investigation into the use of gamma irradiation to induce germination in the seed of the oil palm (Elaeis guineensis Jacq.). Ghana Journal of Agricultural Science, 9, 235-236.
33. Chin, H.F., Hor, Y.L. and Mohd Lassim, M.B. (1984). Identification of recalcitrant seeds. Seed Science and Technology, 12, 429-436.
PHOENIX
|
P. acaulis |
|
|
P. canariensis Chabaud. |
|
|
P. dactylifera L. |
date palm |
|
P. Loureiri Kunth. [P. roebelenii O'Brien; P.
humilis Royle var hanceana Becc.; P. humilis Royle var
Loureiri Becc.] |
|
|
P. reclinata Jacq. [P. spinosa Thonn.; P.
natalensis Hort.] |
|
|
P. rupicola T. Anders |
|
|
P. sylvestris Roxb. |
wild date |
|
P. zeylanica |
|
I. Evidence of dormancy
The germination of seeds of Phoenix spp. can be slow (1,7,8). After-ripening for 2 months is required to remove dormancy in P. dactylifera (2).
II. Germination regimes for non-dormant seeds
-
III. Unsuccessful dormancy-breaking treatments
P. dactylifera
Constant temperatures: 40°C (14)
Pre-soak: 77°C, then cool, 24h (11); cold, 24h (11)
P. Loureiri
Constant temperatures: 40°C (13,15)
Scarification: concentrated sulphuric acid, 2-16 min (5)
P. sylvestris
Pre-soak: 7d, then warm stratification, 39.5°C, 80d, germinate at 27°C (12)
IV. Partly-successful dormancy-breaking treatments
P. acaulis
Pre-soak: 7d, then warm stratification, 39.5°C, 80d, germinate at 27°C (12)
P. Loureiri
Constant temperatures: 25°C, 35°C (15)
P. sylvestris
Constant temperatures: 25°C, 35°C, 40°C (15)
V. Successful dormancy-breaking treatments
P. canariensis
Pre-wash: then germinate at 20°/30°C (7)
P. dactylifera
Constant temperatures: 25°C, 30°C, 35°C (14)
Warm stratification: 25°C, 12d, germinate at 30°C (6); 30°C, 5d, germinate at 25°C (6)
Pre-soak: 6-8w (1)
Pre-wash: then germinate at 20°/30°C (7).
P. Loureiri
Constant temperatures: 24°-28°C (4); 30°C (15); 25°C, 30°C, 35°C (13)
Pre-wash: then germinate at 20°/30°C (7)
P. reclinata, P. rupicola
Pre-wash: then germinate at 20°/30°C (7)
P. sylvestris
Constant temperatures: 30°C (15)
Pre-wash: then germinate at 20°/30°C (7)
VI. Comment
Despite suggestions to the contrary, P. dactylifera shows orthodox seed storage characteristics (2,6,11) and can be stored successfully under IBPGR preferred conditions (6). Moist sand or paper towels are suitable media for laboratory germination tests (6,13-15). The optimum constant temperature for the germination of seeds of Phoenix spp. is between 25° and 30°C (13-15). Above this range germination is reduced (15), with the exception of P. dactylifera which germinates well at 35°C (14) and P. sylvestris where some seeds can germinate at 40°C (15). Provided the test duration is sufficient, seeds of P. Loureiri will germinate at 15°C (13). Alternating temperature regimes are more likely to be effective germination test regimes than constant temperatures (10), one alternation may be sufficient (6); seeds of 7 Phoenix spp. have been reported to germinate well under alternating temperature regimes between 20° and 30°C in plastic tunnels (7).
It is therefore suggested that seeds be tested for germination in an alternating temperature regime of 20°/30°C (8h/16h?) or, if this is not possible, at a constant temperature of 30°C. The test duration must be sufficient to enable all viable seeds to germinate. The following test periods have been used: 4 months for P. acaulis (12); 39 (8) or 60 days (7) for P. canariensis; 49 (11), 56 (7) or 78 days (8) for P. dactylifera; 39 (8-10), 49 (4), 52 (3) or 65 days (7) for P. Loureiri; 42 (9,10), 67 (8) or 76 days (7) for P. reclinata; 60 (3), 92 (7) or 114 days (8) for P. rupicola; 64 days for P. sylvestris (7); and 25 days for P. zeylanica (8).
VII. References
1. Ammons, N.P. (1926). Date seed germination. Proceedings of the West Virginia Academy of Science, 1, 23.
2. Aroeira, J.S. (1962). [On dormancy and seed storage of some fruit trees.] Experientiae, 2, 541-609.
3. Basu, S.K. and Mukherjee, D.P. (1972). Studies on the germination of palm seeds. Principes, 16, 136-137.
4. Bunker, E.J. (1976). Germinating palm seeds. Combined Proceedings of the International Plant Propagator's Society, 25, 377-378.
5. Dickey, R.D. (1953). Germination of pigmy date palm seed as affected by treatment with sulphuric acid. Proceedings of the Association of Southern Agricultural Workers, 50, 139.
6. Ellis, R.H., Hong, T.D. and Roberts, E.H. (1984). Orthodox seed storage behaviour in date palm (Phoenix dactylifera L.) Plant Genetic Resources Newsletter. (In press).
7. Ishihata, K. (1974). [Studies on the morphology and cultivation of palms. On the germination of seed in ornamental palms.] Bulletin of the Faculty of Agriculture, Kagoshima University, 24, 11-23.
8. Koebernik, J. (1971). Germination of palm seed. Principes, 15, 134-137.
9. Loomis, H.F. (1958). The preparation and germination of palm seeds. Principes, 2, 98-102.
10. Loomis, H.F. (1961). Culture of the palms. Preparation and germination of palm seeds. American Horticultural Magazine, 40, 128-130.
11. Nixon, R.W. (1964). Viability of date seeds in relation to age. Report 41st Annual Date Growers' Institute Coachella, 3-4.
12. Rees, A.R. (1963). Germination of palm seeds using a method developed for the oil palm. Principes, 7, 27-30.
13. Sento, T. (1970). [Studies on the germination of seed of the palm. II. On the Livistona chinensis (R. Brown), Phoenix roebelenii (O'Brien) and Sabal species.] Journal of the Japanese Society for Horticultural Science, 39, 261-268.
14. Sento, T. (1972). [Studies on the seed germination of palms. V. On Chrysalidocarpus lutescens, Mascarena verschaffeltii and Phoenix dactylifera.] Journal of the Japanese Society for Horticultural Science, 41, 76-82.
15. Sento, T. (1974). [Studies on the seed germination of palms. VI. On Cocos nucifera L., Phoenix humilis Royle var. hanceana Becc. and Phoenix sylvestris Roxb.] Journal of the Japanese Society for Horticultural Science, 42, 380-388.
