ASD CR 2012 Alizaga Et Al - Seed Germination in Oil Palm (Elaeis Guineensis) - Effect of Seed Storage Time Before and After Heat Treatment for Breaking Dormancy

8/11/2019 ASD CR 2012 Alizaga Et Al - Seed Germination in Oil Palm (Elaeis Guineensis) - Effect of Seed Storage Time Befor

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ASDOIL PALM PAPERS


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Oil Palm Papers, N 38, 2012

Seed germination in oil palm ( Elaeis guineensis ):effect of seed storage time before and

after heat treatment for breaking dormancy

Abstract

Ramiro Alizaga , Jorge Herrera and Amancio Alvarado1 1 2

Heat treatment is the procedure used commercially to overcome seed dormancy inoil palm ( Elaeis guineensis ). However there is no information regarding the combinedeffect of different periods of heat treatment on the germination of seed stored

before or after such treatment. Seeds of the Deli x Ekona variety that were not storedor had been stored for 60 days, were subjected to 0, 10, 20, 30, 40, 45 and 50 daysof heating (40 C). In another experiment, the seeds were subjected to the followingcombinations of prior storage (in days) and heat treatments (in days): 0-50, 10-40,20-30, 30-20, 40-10, 50-0, 60-50, 70-40, 80-30, 90-20, 100-10 and 110-0. Heattreatment for 10, 20 and 30 days increased the percentage of germinated seeds andnormal seedlings; especially when applied to seeds stored previously for 60 days,although these percentages were reduced when the heat treatment was extended to45 or 50 days. It was found that prior storage reduced the intensity of seeddormancy and heating periods of 45 or 50 days negatively affected seedphysiological quality. A positive effect of storage following heat treatment ongermination was also observed in seeds, even with a heat treatment of only 10 days.Furthermore, in seeds with no prior storage, no negative effect was observed due tothe longer heating periods (45 and 50 days).

Centro para Investigaciones en Granos y Semillas, Universidad de Costa Rica, [email protected] de Costa Rica, [email protected]

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Introduction

Palm seeds (Arecaceae) commonly showextended dormancy periods and do notgerminate soon after ripening and detachedfrom bunches (Ellis et al. 1985). According toTomlinson (1990), not less than one fourth ofpalm species require 100 or more days togerminate, and even after that period,germination can be as low as 20%. Thedormancy period is a nuisance for thecommercial production of germinated palmseeds, since most species are seed propagated.

Germination of oil palm seeds under naturalconditions is very low (Murugesan et al. 2005),and dormancy is due to physiological andmorphological impediments (Baskin and Baskin1998). Breeding programs and commercial seed

Materials and Methods

All experiments were performed on recentlyharvested seeds of the tenera variety Deli x Ekonaobtained from the ASD Costa Rica breeding gardenin Coto, in Costa Ricas southern Pacific region.The experiments were conducted at CIGRAS (Grainand Seeds Research Center of the University ofCosta Rica). Seeds from different bunchesharvested the same day were mixed in order to getenough material for all experiments, and threehomogeneous seed sub-lots for the threeexperiments were obtained.

Seeds were kept at 18-20C, with a moisture

content of 18% (dry base) during storage beforeand after the heat treatment for breakingdormancy (40 C). During this period, seeds werekept in polyethylene bags (0.17 mm, flexoprint)that were hermetically closed to maintain seedmoisture content.

For a first experiment, seeds that were fresh or thathad been stored for 60 days were used incombination with a heat treatment and subsequentstorage for a total of 50 days in all cases.

The days of heat treatment-days of subsequentstorage combinations were: 0-50, 10-40, 20 -30,30-20, 40-10, 45-5 and 50-0.

In a second experiment, seeds that were fresh orthat had been stored for 60 days were thenexposed to heat treatments for 0, 10, 20, 30, 40, 45(commercial) or 50 days. In the final experiment,seeds received the following combinations oftreatments (days of prior storage-days of heattreatment): 0-50, 10-40, 20-30, 30-20, 40-10, 50-0,60-50, 70-40, 80-30, 90-20, 100-10 and 110-0.

After applying the treatments, the seeds weresoaked in tap water for seven days and then airdried for approximately eight hours. After this,seeds were divided into groups of 100 (21-22%moisture content, dry basis), treated with acommercial fungicide (Vitavax 400: carboxin 20%+ thiram 20%), and put into polyethylene bags thatwere placed in the germination room where theaverage temperature was 29 C during the day and25 C at night. There were four replications of 100seeds each.

producers normally use a heat treatment to breakdormancy and accelerate and increase

germination. The most common procedure is dryheat treatment: 40 C for 40-70 days (Corrado andWuidart 1990, Osafo et al. 1988). Other treatmentsare not as efficient, such as immersing the seeds ina hydrogen cyanamid solution (CHN N : 2%) for 24hours (Herrera et al. 1998).

The dry heat method of Rees (1959), later modified by Mok and Hor (1977) and Corrado and Wuidart(1990), has been used to promote germination ofoil palm seeds regardless of their origin. Thispaper presents information on the influence ofstorage on oil palm seeds before and after thenormal heat treatment for breaking dormancy (ora variation of this treatment).

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The variable evaluated was the percentage ofgermination ( sensu stricto : at 7, 14, 21 and 28 daysafter initiating the tests). During the lastevaluation (28 days), the percentage of normal andabnormal plantlets (loss of geotropism, weak

plantlets, and lack of radicle or plumule) wasdetermined. An analysis of variance was performedwith data for percentage of germination (7, 14 and28 days (accumulated)), and that of normalplantlets. Means were separated by Tukey test.

Seed dormancy is an adaptive solution of plants toguarantee their survival in time and space. Theintensity and duration of dormancy is determined

by genetic factors, whose expression is influenced

by the environment before and after the seedreaches its physiological ripeness (Bethke et al.2004, Baskin and Baskin 1998). In oil palm,dormancy is interrupted by a heat treatment(40C) during a variable period of time(Addae-Kagyah et al. 1988, Mok and Hor 1977).The main objective is to obtain the largestpercentage of germination in the shortest period.

Data from the first experiment showed asignificant positive effect on germination ( p 0.01)

of the 60-day storage period, even with 0 or 10days of subsequent heat treatment, as assessedat 14 days. By contrast, germination wassignificantly reduced ( p 0.05) when the seed

was previously stored for 60 days and thensubjected to heat treatments of 45 or 50 days(Fig. 1). Increasing the duration of the heattreatment between 10 and 50 days promoted

better germination when the seed was notpreviously stored after harvesting. When seedswere stored for 60 days, germination at sevendays was higher in those treatments with thefollowing combinations: 10-40, 20-30 and 30-20(days of heat treatment and prior storage)(Fig. 2).


Results and Discussion

G e r m

i n a t

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( % )

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0 - 50 10 - 40 20 - 30 30 - 20 40 - 10 45 - 5 50 - 0

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Days of heat (40 C) + storage days after heat

cd

f ef

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Non-stored seeds Days of previous storage

Fresh seeds or stored for 60 days

Fig.1. Percent germination (at 14 days) of oil palm seed with no prior storage or 60 days of storage priorto heat treatment (40 C). Seeds were grouped to receive one of several combinations of days of heat andposterior storage period. Columns with the same letters do not differ (Tukey: p 0.05).

First experiment


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Regardless of the duration of the prior storageperiod, germination at 7, 14 and 28 days wasalways lower in groups of seeds that receivedno heat treatment and were later stored for 50days. Germination did not increase much

between 14 and 28 days, since it had alr eady been qui te high at seven days (Figs. 1, 2).Germination improved in all groups of seedsthat received the heat treatment, but thedifferences were not large from a practicalpoint of view. The positive effect of the heattreatment for breaking dormancy in oil palmseeds has been well documented in the

literature (Hussey 1958, Rees 1959, Mok andHor 1977, Zambrano 1991). A heat treatmentof only ten days followed by 40 days of storagewas enough to get 60 and 78% germination atseven and 28 days respectively (Fig. 2).

With the exception of the non-heatedtreatment (0-50: 7% germination at sevendays), no differences were observed in all othertreatments without prior storage (from 60 to76% germination). The situation was similarafter 28 days, but germination reached up to90% in some treatments.

Percent germination was very low for recentlyharvested seeds (dormant), but after storagefor 60 days, germination was 29% (Figs. 1, 2).

The positive effects of storage have been welldocumented (Adkins W. et al. 2002, Betake etal. 2004, Hacker J. 1984, Tiwari et al. 2004).

Results from the first experiment indicatedthat dormancy in oil palm seeds can beinterrupted by some period of storage beforeand after a heat treatment. However, periods

longer than 45 days in seeds previously storedfor 60 days apparently had negative effectsand germination was reduced, at least in the

genotype studied. In these seeds, dormancycould have already been partially broken;hence the heat treatment applied to seeds withlonger storage periods had rather severeeffects on them. Actually, it appears thatdormancy in about one third of the seeds can

be broken with even a shor t per iod of storage.

0

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G e r m

i n a t

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( % )

0 - 50 10 - 40 20 - 30 30 - 20 40 - 10 45 - 5 50 - 0 0 - 50 10 - 40 20 - 30 30 - 20 40 - 10 45 - 5 50 - 0

Days of heat (40 C) + storage days after heat

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aa

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bb

c c cc c c c

cd d d

cd

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No prior storage - 7 days

60 days of prior storage -7 days

No prior storage - 28 days

60 days of prior storage - 28 days

Fig. 2. Percent germination after 7 and 28 days in seeds with and without 60 days of prior storage andsubsequently exposed to several combinations of heat treatment and posterior storage. Columns of thesame type with the same letters do not differ (Tukey: p 0.05).


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The highest percentage of normal seedlings wasobtained with seeds previously stored for 60 days(p 0.01) and heat treated for 10, 20 or 30 dayscombined with decreasing lengths of time inpost-storage of 40, 30 or 20 days. With longerperiods of heating (45 and 50 days) the percentage

of normal plantlets was reduced ( p 0.05). But forseeds with no prior storage, a longer heating periodof 45 or 50 days was needed to attain similar highvalues, which is an indication that these seeds werein a deeper dormancy before receiving the heattreatment (Fig. 3).

The information obtained from the firstexperiment indicated that a storage period beforethe heat treatment for breaking dormancy had a

better effect on posterior germination of oil palmseeds than storage after the heat treatment. This

information was taken as the basis for planning asecond experiment where the heating periods werestudied further.

Once again, it was found that prior storage of seeds(before they were exposed to heat to breakdormancy) favored posterior germination. This wasclear from data taken at seven and 14 days afterplacing the seeds for germination. In general, the

highest germination was obtained with heattreatments lasting 30 or more days. With 40 or 45days of heat treatment, maximum germination wasobtained in just two weeks (Fig. 4).

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Fig. 3. Percentage of normal plantlets (7 and 28 days) obtained from seeds with or without 60 days ofprior storage and later subjected to different combinations of heat treatment durations and subsequentstorage periods. Same letters indicate no differences (Tukey: p 0.05).

N o r m a l p

l a n t

l e t s ( % )

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Days of heating + days of storage afterward

0 - 50 10 - 40 20 - 30 30 - 20 40 - 10 45 - 5 50 - 0

No prior storage 60 days of prior storage

b

a

cdcd

c

deefg efg

ghighi

fghi fghi fghi

i

Second experiment


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Prior storage takes on more importance forheating periods shorter than 30 days, and theinverse also seems to be also true, sincegermination decreased (p 0.05) with a 60-dayprior storage treatment and heating for 50 days.As suggested before, the effect could be one of anexcessively long heating period on seeds wheredormancy had been already partially broken.When seed is previously stored for about twomonths, a heating period of one month seems to

be enough to break dormancy satisfactorily tothen get a high percentage of germination.

Regardless of the length of the storage period(before or after heating), germination at 14 and28 days was improved by increasing the heatingperiod to 30 or 45 days (Fig. 5). Zambrano (1991)had found that germination was initially ratherlow after a heating treatment of only 20 days,

but with time an acceptable level was reached.

14 days 28 days

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0 10 20 30 50 40 45

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40

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Days of heating (40 C)

G e r m

i n a t

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( % )

Fig. 4. Effect of heat treatment periods on seed germination regardless of storage before or after heating.Columns with the same letters are not different (Tukey: p 0.05).

Fig. 5. Effect on seed germination of several heating periods to break dormancy after 14 and 28 days, inseeds with and without prior storage. Columns with the same letters do not differ (Tukey: p 0.05).

0

20

40

60

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G e r m

i n a t

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a

b bb

cd

c

e e ee e e

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cde

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0 10 20 30 40 45 50 0 10 20 30 40 45 50

No prior storage-14 days 60 days of prior storage-14 days

No prior storage-28 days 60 days of prior storage-28 daysA B


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Most seeds that germinated had normalmorphology and it was again observed that rapidgermination gave rise to more normal plantlets.The 50-day heat treatment in seeds storedpreviously showed more abnormal plantlets (Fig.6). These observations clearly indicate that the heattreatment should definitely consider the priorstorage history of the seeds.

Concerning the percentage of normal plantlets,heat treatments of 0, 10 and 20 days were generallynot suitable for overcoming seed dormancy, from a

commercial standpoint. In contrast, non-storedseeds heated for 40, 45 and 50 days and storedseeds heated for 30, 40 and 45 days attained higherpercentages of normal plantlets (p 0.05) rangingfrom 85 to 90%. In contrast, treatment with priorstorage and 50 days of heat treatment showed asignificant decrease in the percentage of normalplantlets (P 0.05) with respect to the besttreatments (Fig. 6). This further strengthens theposition that the heat treatment should not bedone indiscriminately and the history of the seedshould be taken into account.

This experiment was conducted to evaluate storageperiods longer than 60 days prior to the heatingtreatment. The positive effect ( p 0.01) of anappropriate combination of prior storage and theposterior heat treatment was corroborated. Withinthe range studied, the best treatments forstimulating germination and normal plantlets werethose where the prior storage period lasted 70 to

90 days combined with 40 to 20 days of heattreatment. Of similar magnitude was thegermination obtained from heating the seeds for50, 40 and 30 days, but with shorter periods ofprior storage (0, 10 and 20 days). These resultsagree with those observed in previous experiments.Once again, the best treatment for germinationalso gave rise to higher quality plantlets (Fig. 7).

Fig. 6. Percentage of normal plantlets at 28 days obtained from seed with and without 60 days of storageprior to heating. Numbers with same letter do not differ (Tukey: p 0.05).

N o r m a l p

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0 10 20 30 40 45 50

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Third experiment


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Most seeds that germinated in all threeexperiments were morphologically normal andthe small percentage of adnormalities were notrelated to any treatment in particular. It wasclear that those seed lots that germinated fasterafter soaking in water produced higher numbersof normal plantlets. When germination reached85% or more after seven days, the plantletsobtained were more vigorous. On the contrary,more adnormalities were found in those seedsthat germinated later. Faster germination may bea consequence of higher seed vigor (Associationof Official Seed Analysis 2002, Tekrony and Egli1991) or the result of a partially brokendormancy or combination of both factors.

A period of storage prior to the heat treatmentfor breaking dormancy allowed a reduction inheat exposure, faster germination and moreplantlets with desirable characteristics. All thisreduces time and cost during seed processing forgemination.

Corrado and Wuidart (1990) obtained highgermination after six months of storage and byusing heat 39 C) for 80 days. However, ourresults indicate that there can be a negativeeffect on germination if the seed is stored for

50-60 days and then exposed to a prolongedperiod of heating (40C: 45-50 days), at least forthe seed variety used in these experiments. Asimilar situation was found by Beugr et al.(2009), how noted a negative effect of the heatingtreatment on germination in oil palm seeds thatwere stored for increasing periods of time.

There are other possibilities that could helpreduce the dormancy period in oil palm seeds,

but they have not been widely accepted. Forexample, Myint el al. (2010) determinated that byremoving the operculum, germination couldreach up to 80%, comparable to the resultsobtained with the heating method.

Oil palm dormancy seems to be the result of bothphysical and physiological impediments forgermination, which was confirmed by the work ofJimnez el al. (2008), who found an importantreduction in abscisic acid concentration after theheat treatment. It is however possible that seedsfrom different genotypes (Beugr et al. 2009),latitudes and even ripeness may showdifferences when exposed to a particulartreatment to break dormancy.

Fig. 7. Germination and normal plantlets (28 days) from seeds that recieved different combinations of prior storage

and days of heat treatment for breaking dormancy. Data with the same letters do not differ (Tukey: p 0.05).

0

0-50 10-40 20-30 30-20 40-10 50-0 60-50 70-40 80-30 90-20 100-10 1 01-0

20

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Prior storage + Heat treatment (40 C)

P o r c e n t c c c

c c c

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Germination 28 days Normal plantlets 28 days


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Literature

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Addae-Kagyah K. A., Osafo D. M., Olympio N. S., AtubraO. K. (1988). Effect of seed storage, heat pre- treatment

and its duration on germination and growth of nurserystock of the idolatrica palm, Elaeis guineens is varidolatrica (Chevalier). Trop. Agric. (Trinidad) 65:77-83

Adkins S., Bellairs S., Loch D. 2002. Seed dormancymechanisms in warm season grass species. Euphytica 126: 1320

Association of Official Seed Analysts (AOSA). (2002).Seed Vigor Testing Handbook. Contribution No. 32.Association of Official Seed Analysts. New Mexico88003

Baskin C.C., Baskin J. M. (1998). Seeds. Ecology,biogeography, and evolution of dormancy andgermination. Academic Press, San Diego, 666p

Bethke, P., Gubler, F., Jacobsen J., Rusell J. 2004.Dormancy of Arabidopsis seeds and barley grains canbe broken by nitric oxide. Planta 219(5): 847855

Beugr-Manhonon M., Kouakou-Kouakou L.,Bognonkp J.P., Konan- Kouakou, E., Kouakou-TanohH., Kouadio-Yatty J. (2009). African J. of Agric. Res.4(10):931-937

Corrado F., Wuidart W. (1990). Germination des graines

de palmier huile (Elaeis guineensis) en sac depolythylne. Mthode par "chaleur sche" Olagineux45 (11) : 511-518

Ellis R. H., Hong, T. D., Roberts E. H. (1985). Handbookof seed technology for genebanks. Vol. II:Compendium of specific germination information andtest recommendations, International Board for PlantGenetic Resources, Rome, 456 p

Hacker J. B., Andrew M. H., McIvor J. G., Mott J. J. 1984.Evaluation in contrasting climates of dormancycharacteristics of seed of Digitar ia milanjiana . J. ofApplied Ecology 21(3): 961-969

Herrera J., Alizaga R., Guevara E. (1998). Use of chemical

treatments to induce seed germination in oil palm( Elaeis guineensis Jacq.). ASD Oil Palm Papers 18: 1-1

Hussey G. (1958). An analysis of the factors controllingthe germination of the seed of oil palm, Elaeis

guineensis (jacq.). Annals of Bot. 22:259-284

Jimnez, V., Guevara, E., Herrera, J., Alizaga, R.,Bangerth F. (2008). Changes in hormoneconcentrations during dormancy release of oil palm(Elaeis guineensis) seeds. Seed Science andTechnology 6(3): 575-587

Mok C. K. and Hor Y. L. (1977). The storage of oil palm( Elaeis guineensis ) seed after high temperaturetreatment. Seed Science and Technology 5: 499-508

Murugesan P., Mathur R. K., Pillai R. S. and Babu M. K.(2005). Effect of accelerated aging on seed

germination of oil palm ( Elaeis guineensis Jacq. var.dura Becc.). Seed Technology 27(1): 108-112

Murugesan, P., Bijimol G. and Haseela H. 2008. Effect ofdifferent substrates on growth of germinated oil palmhybrids seeds. Indian J. of Hort. 65(4)

Myint, T., Chanprasert W., Srikul S. Germination of seedof oil palm ( Elaeis guineens is Jacq.) as affected bydifferent mechanical scarification methods. Seed Sci.and Tech. 38 (3): 635-645

Rees A. R. (1959). Germination of oil palm seed: largescale germination. J. of West African Inst. for Oil Palm

Res. 3:76-82

Tekrony D. M., Egli D. B. (1991). Relationship of seedvigor to crop yield: A Review. Crop Sci. 31:816-822

Tiwari, C.; Sharma, S.; Verma, R. 2004. Effect offungicide and plant growth hormones on germinationof teak ( Tectona grandis ). J. of Trop. Forest Sci.16:25-34

Tomlinson P. B. (1990). The structural biology of palms.Oxford University Press, New York. 477 pp

Zambrano R. 1991. Influencia de perodos de

almacenamiento y calentamiento sobre la germinacinde semilla de palma africana. Tesis de grado. Fac. Ing.Agron. Universidad Tcnica de Manabi (Ecuador). 70 p


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Germinacin de semillas de palma aceitera(Elaeis guineensis ): almacenamiento previo y posterior

al tratamiento de calor para romper el reposo

Resumen

Ramiro Alizaga , Jorge Herrera y Amancio Alvarado1 1 2

El tratamiento trmico es el procedimiento utilizado comercialmente para superarel reposo en semillas de palma aceitera ( Elaeis guineensis ). Sin embargo no hayinformacin con respecto al efecto combinado de diferentes perodos detratamiento trmico sobre la germinacin de semilla almacenada previa oposteriormente a dicho tratamiento. Semillas del hbrido Deli x Ekona (DXE) sinalmacenamiento previo y almacenadas por 60 das, se sometieron a 0, 10, 20, 30, 40,45 y 50 das de calor (40C). Tambin se sometieron a las siguientes combinacionesde almacenamiento previo por tratamiento trmico (en das): 0-50, 10-40, 20-30,30-20, 40-10, 50-0, 60-50, 70-40, 80-30, 90-20, 100-10 y 110-0. El tratamientotrmico por 10, 20 y 30 das aument el porcentaje de semillas germinadas y deplntulas normales, en especial cuando se aplic a semillas almacenadaspreviamente por 60 das; aunque dichos porcentajes se redujeron cuando eltratamiento trmico se aplic por 45 o 50 das. Tambin se observ un efectopositivo del almacenamiento posterior an con tratamiento trmico de slo 10 das.Se determin que el almacenamiento previo reduce la intensidad del reposo de lassemillas, por lo que perodos prolongados de calentamiento (45 o 50 das) afectannegativamente la calidad fisiolgica de las mismas. Por el contrario, en semilla sinalmacenamiento previo no se observ efecto negativo de los perodos decalentamiento mayores (45 y 50 das).

Centro para Investigaciones en Granos y Semillas, Universidad de Costa Rica, [email protected] de Costa Rica, [email protected]

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Introduccin

Las semillas de palmas (Arecaceae) en generalpresentan perodos de reposo extensos; por lo que

recin cosechadas germinan en baja proporcin (Elliset al. 1985). Segn Tomlinson (1990), al menos unacuarta parte de las especies de palmas requieren unplazo mayor de 100 das para germinar y durante esteperodo solo se obtiene 20 % de la germinacinpotencial. Esta condicin de reposo restringe odificulta la propagacin comercial de las diferentesespecies de palmas, las cuales salvo muy pocasexcepciones, nicamente se propagan por semillasexual.

En condiciones naturales las semillas de palmaaceitera germinan espordicamente y en bajaproporcin (Murugesan et al. 2005). El reposo se debea impedimentos fisiolgicos y morfolgicos (Baskin yBaskin 1998), y es un inconveniente que las compaasque comercializan semilla germinada deben superar atravs de algn tratamiento que acelere lagerminacin.

Comnmente el reposo de las semillas se interrumpecon un tratamiento de calor (seco o hmedo: 40 C)

durante 40-70 das (Corrado y Wuidart 1990, Osafo etal. 1988). Otro tratamiento, aunque no tan eficientecomo el anterior, es la inmersin de las semillas enuna solucin de cianamida hidrogenada (CHN2N2) al2% durante 24 horas (Herrera et al. 1998).

El mtodo de calor seco propuesto por Rees (1959) yluego modificado por Mok y Hor, (1977) y Corrado yWuidart (1990) se ha usado en forma indiscriminadapara promover la germinacin de la semilla de lapalma aceitera de diferentes orgenes. Sin embargo, nose dispone de informacin relacionada con lainfluencia de perodos de almacenamiento previos oposteriores al tratamiento tradicional con calor o avariaciones del mismo, sobre la germinacin de lassemillas. El objetivo de este trabajo fue evaluar lainfluencia de los perodos de almacenamiento previo yposterior al tratamiento usual de calor, o variacionesdel mismo.

Materiales y MtodosLos experimentos se realizaron con semillas recincosechadas de Elaeis guineensis del tipo tenera(Deli x Ekona) suministradas por ASD Costa Rica.Para obtener suficiente semilla para los diferentesexperimentos se mezclaron racimos con la mismaedad de cosecha, y se obtuvo tres sublotesrepresentativos y homogneos. En los experimentos en que se almacen semillaprevio y posterior al tratamiento trmico (calorseco), las mismas se mantuvieron a 18-20 C, conun contenido de humedad de 18% en base seca.Para los tratamientos trmicos, las semillas sealmacenaron a 40 C con 18 % de contenido dehumedad (base seca), en bolsas de polietileno de0.17 mm de espesor (Flexoprint) hermticamentecerradas para mantener el contenido de agua delas semillas.

En un primer experimento, las semillas sealmacenaron previamente durante cero o 60das, y luego se hicieron las siguientescombinaciones segn el tratamiento trmico y elalmacenamiento posterior; de tal manera quesiempre sumaran 50 das: 0-50, 10-40, 20-30,30-20, 40-10, 45-5 y 50-0.

En un segundo experimento, las semillas sealmacenaron por cero o 60 das, y en cada casose sometieron a tratamientos trmicos de 0, 10,20, 30, 40, 45 (tratamiento comercial) y 50 das.En un tercer experimento, las semillas sesometieron a las siguientes combinaciones dealmacenamiento previo por tratamiento trmico(en das): 0-50, 10-40, 20-30, 30-20, 40-10, 50-0,60-50, 70-40, 80-30, 90-20, 100-10 y 110-0.


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Una vez realizados los tratamientos, las semillasse sumergieron en agua corriente durante sietedas y se colocaron al aire ambiente duranteaproximadamente ocho horas; luego de lo cual sehicieron grupos de 100 semillas (21-22 % dehumedad, base seca), se trataron con el fungicidacomercial Vitavax 400 (carboxin 20% + thiram20%), se introdujeron en bolsas de polipropileno,y se colocaron en cuartos de germinacin, dondela temperatura promedio fue de 29 C durante elda y de 25 C durante la noche.

Cada tratamiento tuvo cuatro repeticiones de 100semillas cada una. Las variables evaluadas fueron elporcentaje de germinacin ( sensu stricto : a los 7, 14,21 y 28 das despus de iniciada la prueba), elporcentaje de plntulas normales (28 das) y elporcentaje de plntulas anormales (prdida degeotropismo, plntulas raquticas y falta de radculao plmula). Se realiz luego un anlisis de varianzapara cada experimento, con las variables semillagerminada (7, 14 y 28 das (acumulado), y para elporcentaje de plntulas normales. La separacin demedias se hizo mediante la prueba de Tukey.

El reposo en las semillas es una solucin adaptativade las plantas para garantizar su sobrevivencia en eltiempo y el espacio. La intensidad y permanencia delmismo est determinada por factores genticos quea la vez son influenciados por el ambiente antes ydespus de la madurez fisiolgica de las semillas(Bethke et al. 2004, Baskin y Baskin 1998). Pararomper el reposo y estimular luego la germinacinde las semillas, normalmente se utiliza untratamiento trmico (40C) durante perodos de

tiempo variables (Addae-Kagyah et al. 1988, Mok yHor 1977). El objetivo es lograr el mayor porcentajede germinacin en el menor tiempo posible.

En el primer experimento se encontr un incrementosignificativo ( p 0.01) en la germinacin debido alalmacenamiento previo (60 das) al calentamiento alos 14 das de iniciada la prueba en los tratamientosde 0-50 y 10-40. Por el contrario, la germinacin seredujo significativamente ( p 0.05) cuando la semilla se almacen previamente por 60 das yposteriormente se someti al tratamiento trmico de45 y 50 das. No se observ efecto en lostratamientos 20-30, 30-20 y 40-10 (Fig.1). El

incremento en los das de calor entre 10 y 45 seasoci con un aumento en la germinacin cuando nose almacen la semilla previamente.

Resultados y Discusin

G e r m

i n a c

i n

( % )

0

0 - 50 10 - 40 20 - 30 30 - 20 40 - 10 45 - 5 50 - 0

20

40

60

80

a

b

100

Das de calor (40 C) + das almacenamiento posterior

cd

f ef

f ef

ef def

def

c

ef f f

Almacenamiento previo 0 das Almacenamiento previo 60 d as.

Semillas frescas o almacenadas durante 60 das

Fig. 1. Porcentaje de germinacin (14 das) de semillas de palma aceitera sin y con 60 das de almacenamiento previoal tratamiento de calor (40 C). Las semillas se agruparon para recibir diferentes combinaciones de das detratamiento trmico y tiempo de almacenamiento posterior. Columnas con igual letra no difieren entre s (Tukey: p

0.05). En el eje x, el primer nmero denota los das de calor y el segundo das de almacenamiento posterior.

Primer experimento


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La germinacin a los siete das fue mayor cuandola semilla se almacen previamente durante 60das con las combinaciones 10-40, 20-30 y 30-20(das de calor y almacenamiento posteriorrespectivamente) (Fig. 2).

Independientemente del almacenamiento previo,la germinacin a los 7 y 28 das de iniciada laprueba fue menor en los grupos de semillas que norecibieron el tratamiento de calor y que luegofueron almacenadas durante 50 das ( p 0.05).Tambin es evidente el efecto positivo ( p 0.01) delalmacenamiento previo sobre la germinacin, yaque no aument mucho entre los 14 y 28 das(final de la prueba) debido a los altos porcentajesque haban sido alcanzados previamente.

La germinacin mejor en todos los grupos desemillas que recibieron calor, pero las diferencias,aunque significativas, no se consideraronimportantes desde el punto de vista prctico.

El efecto positivo del tratamiento trmico fuesignificativo ( p 0.01) en ambos grupos desemillas que recibieron o no un almacenamientoprevio (Figs. 1 y 2). El efecto del calor para romperel reposo de la semilla de la palma aceitera estampliamente documentado en la literatura (Hussey1958, Rees 1959, Mok y Hor 1977, Zambrano1991).

Un periodo de calentamiento de solo 10 das,seguido de 40 das de almacenamiento a 18 C fuesuficiente para obtener 60% y 78% de germinacina los siete y 28 das respectivamente (Fig. 2)

Con la excepcin del tratamiento sin calor (0-50: 7%de germinacin a los siete das), no se encontrdiferencias significativas en los demstratamientos sin almacenamiento previo (60 y 76%de germinacin). A los 28 das la situacin semantuvo, pero la germinacin alcanz 90% enalgunos tratamientos.

0

20

40

60

80

100

G e r m

i n a c

i n

( % )

0 - 50 10 - 40 20 - 30 30 - 20 40 - 10 45 - 5 50 - 0 0 - 50 10 - 40 20 - 30 30 - 20 40 - 10 45 - 5 50 - 0

Das de tratamiento trmico (40 C) + das almacenamiento posterior

a

aa

b

bb

c c cc c c

c cd d d

cd

b b b b

bcbb

b

b

a

Sin almacenamiento previo - 7 das

60 das almacenamiento previo - 7 das

Sin almacenamiento previo -28 das

60 das almacenamiento previo -28 das

Fig. 2. Porcentaje de germinacin a los 7 y 28 das en semillas sin y con 60 das de almacenamiento previoy posteriormente sometidas a diferentes combinaciones en la duracin del tratamiento trmico y elalmacenamiento posterior. Columnas del mismo tipo con igual letra no difieren entre s (Tukey: p 0.05).


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La semilla recin cosechada tuvo una germinacinmuy baja debido a su reposo, pero cuando sealmacen por 60 das, la germinacin se incrementhasta alcanzar 29% (Figs. 1 y 2). El efecto positivo delalmacenamiento est tambin documentado en laliteratura (Adkins W. et al. 2002, Bethke et al. 2004,Hacker J. 1984, Tiwari et al. 2004).

Los resultados de este primer experimento indicanque la germinacin de la semilla de palma aceiterapuede aumentar si esta se almacena por un periodoantes o despus del tratamiento de calor pararomper el reposo. No obstante, periodos mayores a45 das de calor en semillas previamentealmacenadas durante 60 das, redujeron lagerminacin en el genotipo estudiado. En este casopodra haberse presentado una superacin parcialdel reposo, por lo que el tratamiento trmicoaplicado en los perodos mayores pudo afectar lacalidad de las semillas.

El mayor porcentaje de plantas normales se obtuvocon semillas previamente almacenadas durante 60

das ( p 0.01) y con los tratamientos con dascrecientes de calor (10, 20 y 30), combinados concantidad decreciente de das en pos-almacenamiento(40, 30 y 20). Con los mayores periodos decalentamiento (45 y 50 das) se redujo ( p 0.05) elporcentaje de plntulas normales (Fig. 3).

Los mayores porcentajes de plntulas normales ( p 0.05) se obtuvieron con semilla almacenadapreviamente por 60 das con los tratamientos de10-40, 20-30 y 30-20 (das de calor y almacenamientoposterior); sin embargo en los tratamientos de 45-5 y50-0 el porcentaje de plntulas normales mostr unadisminucin ( p 0.05), posiblemente debido a quesufri deterioro por el tratamiento trmico. Por otraparte, en la semilla sin almacenamiento previo (60das), los tratamientos de 0-50 y 10-40 presentaronlos menores porcentajes de plntulas normales ( p 0.05), mientras que los mayores valores seobtuvieron con los tratamientos de 45-5 y 50-0,debido a que presentaban mayor reposo por lo que eltratamiento trmico no afect negativamente elporcentaje de plntulas normales.

14

Fig. 3. Porcentaje de plntulas normales (7 y 28 das) provenientes de semillas sin y con 60 das dealmacenamiento previo, y que luego fueron sometidas a diferentes combinaciones en la duracin del tratamientotrmico y almacenamiento posterior. Resultados con igual letra no difieren entre s (Tukey: p 0.05).

P l n

t u l a s n o r m a l e s

( % )

0

20

40

60

80

100

Das de tratamiento trmico + das almacenamiento posterior

0 - 50 10 - 40 20 - 30 30 - 20 40 - 10 45 - 5 50 - 0

Sin almacenamiento previo 60 das de almacenamiento previo

b

a

cdcd

c

deefg efg

ghighi

fghi fghi fghi

i


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Los datos del primer experimento indicaron que elp e r i o d o d e a l m a c e n a m i e n t o p r e v i o a l

calentamiento para romper el reposo tuvo unefecto mayor sobre la germinacin, que elalmacenamiento posterior al tratamiento trmico.Con esta informacin se plane un segundoexperimento variando el periodo de calentamiento.

El almacenamiento previo al calentamiento

favoreci significativamente la germinacin ( p

0.01) en los recuentos hechos a los 7 y 14 das,

pero no a los 28 das. En general, los mejoresresultados de germinacin se obtuvieron con unperiodo de calentamiento de 30 das o ms. Conun calentamiento igual o superior a los 40 dasse logr la mxima germinacin en solo dossemanas (Fig. 4).

Segundo experimento

Se encontr que cuando no se utilizalmacenamiento previo (60 das), perodos decalentamiento menores a 30 das no produjeronuna germinacin alta. Zambrano (1991) encontrque la germinacin fue lenta con un tratamientode calor de solo 20 das, aunque eventualmente seobtuvo una germinacin aceptable. Adems, con osin almacenamiento previo los valores mayores degerminacin se obtuvieron con 40 y 45 das decalor ( p 0.05). Se observ un descenso en la

germinacin con el tratamiento de 50 das decalor cuando la semilla se almacen previamentepor 60 das (Fig. 5). Esto reafirma la observacinde que el almacenamiento previo reduce laintensidad del reposo de la semilla y la hace mssensible a periodos prolongados con altastemperaturas. Por la misma razn, con unalmacenamiento de dos meses, resulta suficienteun mes de calentamiento para lograr una altagerminacin.

14 das 28 das

0

0 10 20 30 50 40 45

20

40

60

80

100

a

a

b

c

d

dd

d d

dc

a

e e

Das de tratamiento trmico (40 C)

S e m

i l l a g e r m

i n a d a

( %

)

Fig. 4. Efecto del perodo de tratamiento trmico sobre el porcentaje de semillas germinadas, sin consideraralmacenamiento previo o posterior. Columnas del mismo tipo con igual letra no difieren entre s (Tukey: p 0.05).


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Fig. 5. Duracin del tratamiento de calor para romper el reposo y porcentaje de semillas germinadas, con o sin unperiodo de almacenamiento previo. Columnas del mismo tipo con igual letra no difieren entre si (Tukey: p 0.05).

0

20

40

60

80

100

S e m

i l l a g e r m

i n a d a

( % )


a

b bb

cd

c

e e ee e e

d

a a

b

b

ccd

cdede

e e e e e

cd

a

0 10 20 30 40 45 50 0 10 20 30 40 45 50

Sin almacenamiento previo -14 das 60 das de almacenamiento previo -14 das

sin almacenamiento previo -28 das 60 das de almacenamiento previo -28 dasA B

Con respecto al porcentaje de plntulas normales,en general los tratamientos trmicos de 0, 10 y 20das no fueron adecuados, desde un punto de vistacomercial, para superar el reposo de las semillas.Por el contrario, semillas sin almacenamientoprevio con 40, 45 y 50 das de calor y semillas conalmacenamiento previo calentadas por 30, 40 y 45

das alcanzaron porcentajes de plntulas normalessuperiores (p 0.05) que variaron entre 85 y 90%.

En contraposicin el tratamiento conalmacenamiento previo y 50 das de calor,mostr una disminucin significativa en elporcentaje de plntulas normales (p 0.05) conrespecto a los mejores tratamientos (Fig. 6). Loque refuerza la posicin de que el tratamientotrmico no debe realizarse indiscriminadamente

y que debe considerarse el historial de lasemilla.

Fig. 6. Porcentaje de plntulas normales a los 7 y 28 das obtenidas de semillas sin y con 60 das dealmacenamiento previo al calentamiento y luego sometidas a diferentes combinaciones de tratamientostrmicos y de almacenamiento posterior. Nmeros con igual letra no difieren entre s (Tukey: p 0.05).

P l n

t u l a s n o r m a l e s

( % )

0

0 10 20 30 40 45 50

20

40

60

80

100


a

a

b

c d

e

e

gg

g

g

g

fg

f

sin almacenamiento previo 60 das de almacenamiento previo


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En este experimento se evaluaron periodos dealmacenamiento mayores a 60 das previos al

tratamiento de calor. Se corrobor el efecto positivo(p 0.01) del almacenamiento previo en combinacincon el calentamiento, ya que en las tres evaluacionesde germinacin (7, 14 y 28 das), los mejorestratamientos fueron aquellos donde la duracin delalmacenamiento previo fue de 70, 80 o 90 das conperiodos de calentamiento de 40, 30 y 20 dasrespectivamente. En todos los casos, el efecto fuesimilar en lo que se refiere a plntulas

normales (Fig. 7). De similar magnitud fue lagerminacin obtenida con los tratamientos de 50,

40 y 30 das de calor pero con cortos perodos dealmacenamiento previo (0, 10 y 20 das),resultados que coinciden con lo observado en losexperimentos anteriores.

Se observa que los tratamientos trmicos de 0 y 10no son suficientes para superar el reposo (Figs. 5,6 y 7), an con almacenamientos previos tanprolongados como 100 o 110 das.

Tercer experimento

Fig. 7. Porcentaje de semillas germinadas y de plntulas normales a los 28 das en semillas con diferentes perodos dealmacenamiento previo y luego sometidas a diferentes periodos de tratamiento trmico. Columnas y resultados conigual letra no difieren entre s (Tukey: p 0.05).

0

0-50 10-40 20-30 30-20 40-10 50-0 60-50 70-40 80-30 90-20 100-10 1 01-0

20

40

60

80

100

Almacenamiento previo + tratamiento trmico (40 C)

P o r c e n t a j e

c c c

c c c

b

ba

a a

b

b

a

c

c

c

c

c

c b

a

a

b

Semilla germinada 28 das Plntulas normales 28 days

Durante los experimentos, en general se observuna baja proporcin de plntulas anormales(prdida de geotropismo y plntulas raquticas) y elporcentaje observado no se relacion con ningntratamiento en particular. Tambin fue evidenteque las semillas con la germinacin ms temprana(7 das) presentaron los porcentajes ms bajos deplntulas anormales, especialmente cuando lagerminacin fue 85% o mayor. Las anormalidades

aumentaron en las semillas de ms lentagerminacin, lo cual posiblemente se relacione conel vigor de la semilla (Association of Official SeedAnalysts 2002, Tekrony y Egli 1991).

El almacenamiento previo de las semillas (18-20 C)luego de la cosecha contribuye a superar el reposo ypermite entonces utilizar periodos de calentamientoms cortos para obtener altos porcentajes degerminacin y de plntulas normales;

lo cual ahorra tiempo, facilita la entrega de semillasgerminadas a los clientes y garantiza un mayorporcentaje de plantas normales luego de lasiembra en el previvero.

Corrado y Wuidart (1990) obtuvieron una altagerminacin en semilla de Elaeis guineensis luego deseis meses de almacenamiento y un tratamientotrmico de 80 das a 39 C. Por el contrario, los

resultados obtenidos en este trabajo indican que lagerminacin puede verse afectada en forma negativasi se almacena la semilla por 50-60 das y luego seexpone a un periodo de calentamiento (40C) de 50das, al menos en la variedad utilizada en estosexperimentos. Una respuesta similar fue obtenidapor Beugr et al. (2009), quienes determinaron unefecto negativo del tratamiento trmico sobre lagerminacin de semillas de E. guineensis conformeaument el tiempo de almacenamiento.


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Myint et al. (2010) determinaron que la remocindel oprculo en semillas de E. guineensis produjoporcentajes de germinacin mayores de 80% ycomparables con los obtenidos con la aplicacin decalor seco, mientras que Jimnez et al. 2008midieron una importante reduccin en laconcentracin de cido abcsico posterior altratamiento trmico, lo que sugiere que la

latencia en esta especie es un fenmeno fsico yfisiolgico. Tambin es posible que semillas dediferentes genotipos (Beugr et al. 2009), dediversas latitudes, e incluso de diferentesperodos de cosecha puedan comportarse demanera diferente ante un determinadotratamiento de calor para romper su latencia.

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Literatura citada

Addae-Kagyah K. A., Osafo D. M., Olympio N. S., AtubraO. K. (1988). Effect of seed storage, heat pre-treatmentand its duration on germination and growth of nurserystock of the idolatrica palm, Elaeis guineensis varidolatrica (Chevalier). Trop. Agric. (Trinidad) 65:77-83

Adkins S., Bellairs S., Loch D. 2002. Seed dormancymechanisms in warm season grass species. Euphytica 126: 1320

Association of Official Seed Analysts (AOSA). (2002).Seed Vigor Testing Handbook. Contribution No. 32.Association of Official Seed Analysts. New Mexico88003

Baskin C.C., Baskin J. M. (1998). Seeds. Ecology,biogeography, and evolution of dormancy andgermination. Academic Press, San Diego, 666p

Bethke, P., Gubler, F., Jacobsen J., Rusell J. 2004.Dormancy of Arabidopsis seeds and barley grains canbe broken by nitric oxide. Planta 219(5): 847855

Beugr-Manhonon M., Kouakou-Kouakou L.,Bognonkp J.P., Konan- Kouakou, E., Kouakou-TanohH., Kouadio-Yatty J. (2009). African J. of Agric. Res.4(10):931-937

Corrado F., Wuidart W. (1990). Germination des grainesde palmier huile (Elaeis guineensis) en sac depolythylne. Mthode par "chaleur sche" Olagineux45 (11) : 511-518

Ellis R. H., Hong, T. D., Roberts E. H. (1985). Handbookof seed technology for genebanks. Vol. II:Compendium of specific germination information andtest recommendations, International Board for PlantGenetic Resources, Rome, 456 p

Hacker J. B., Andrew M. H., McIvor J. G., Mott J. J. 1984.Evaluation in contrasting climates of dormancycharacteristics of seed of Digitaria milanjiana . J. ofApplied Ecology 21(3): 961-969

Herrera J., Alizaga R., Guevara E. (1998). Use of chemical

treatments to induce seed germination in oil palm( Elaeis guineensis Jacq.). ASD Oil Palm Papers 18: 1-1

Hussey G. (1958). An analysis of the factors controllingthe germination of the seed of oil palm, Elaeisguineensis (jacq.). Annals of Bot. 22:259-284

Jimnez, V., Guevara, E., Herrera, J., Alizaga, R.,Bangerth F. (2008). Changes in hormoneconcentrations during dormancy release of oil palm(Elaeis guineensis) seeds. Seed Science andTechnology 6(3): 575-587

Mok C. K. and Hor Y. L. (1977). The storage of oil palm( Elaeis guineensis ) seed after high temperaturetreatment. Seed Science and Technology 5: 499-508

Murugesan P., Mathur R. K., Pillai R. S. and Babu M. K.(2005). Effect of accelerated aging on seedgermination of oil palm ( Elaeis guineensis Jacq. var.dura Becc.). Seed Technology 27(1): 108-112

Murugesan, P., Bijimol G. and Haseela H. 2008. Effect of

different substrates on growth of germinated oil palmhybrids seeds. Indian J. of Hort. 65(4)

Myint, T., Chanprasert W., Srikul S. Germination of seedof oil palm ( Elaeis guineensis Jacq.) as affected bydifferent mechanical scarification methods. Seed Sci.and Tech. 38 (3): 635-645

Rees A. R. (1959). Germination of oil palm seed: largescale germination. J. of West African Inst. for Oil PalmRes. 3:76-82

Tekrony D. M., Egli D. B. (1991). Relationship of seedvigor to crop yield: A Review. Crop Sci. 31:816-822

Tiwari, C.; Sharma, S.; Verma, R. 2004. Effect offungicide and plant growth hormones on germinationof teak ( Tectona grandis ). J. of Trop. Forest Sci.16:25-34

Tomlinson P. B. (1990). The structural biology of palms.Oxford University Press, New York. 477 pp

Zambrano R. 1991. Influencia de perodos dealmacenamiento y calentamiento sobre la germinacinde semilla de palma africana. Tesis de grado. Fac.Ing. Agron. Universidad Tcnica de Manabi (Ecuador).70 p


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ASD CR 2012 Alizaga Et Al - Seed Germination in Oil Palm (Elaeis Guineensis) - Effect of Seed Storage Time Before and After Heat Treatment for Breaking Dormancy