J- Agronomy & Crop Science 175, 51—56 (1995)© 1995 Blackwell Wissenschafts - Verlag, BerlinISSN 0931-2250

Department of Crop Science^ Faculty of Agriculture^ University of Peradeniya, Sri Lanka

Pod, Seed and Germination Characteristics of Selected Cardamom(Elettaria cardamomum (Linn.) Maton) Varieties

U. R. SANGAKKARA

Author's address: Dr. U. R. SANGAKKARA, Faculty of Agriculture, University of Peradeniya, Sri Lanka

With 2 tables and 1 figure

Received September 23, 1994; accepted January 12, 1995

Abstract

Cardamom is a popular and important tropical spice, traditionally propagated by rhizomes, although seedswhich are considered recalcitrant are being increasingly used in planting programmes. Thus a study evaluatedthe effects of pod maturity on pod, seed and germination characteristics of three popular varieties, along withthe influence of drying on seed germinability.

Green and yellow mature pods and seeds of all varieties had a high moisture content. The variety Mysore,which IS considered high yielding, had larger pods with a greater number of heavy seeds. Although the podsof Vazukka were heavier than the Malabar variety due to greater seed weights, seed numbers were similar inboth varieties. Seed moisture contents declined with increasing pod maturity, while seed weights andgerminability increased.

The germinability of Mysore seeds were greater, while that of the other varieties were lower. The largerseeds of all varieties germinated 15—20 days earlier, giving rise to a greater percentage (20—25 %) of seedlings.Desiccation at 20 °C maintained germinability for a longer period (5—9 days) in all varieties, than when driedat 30 °C. The seeds of the variety Mysore was more tolerant to desiccation than other varieties. The studyillustrated the importance of selecting large seeds from yellow mature pods of cardamom for propagation andthe value of establishment immediately after harvest to obtain a greater number of seedlings.

Key words: Cardamom, pods, seeds, germination, desiccation

Introduction

Cardamom {Elettaria cardamomum (Linn.)Maton) IS a popular tropical spice crop, cul-tivated extensively in the humid Asian regionsfor its aromatic seeds (PURSEGLOVE et al. 1981)which are used in pharmaceutical and culinaryindustries. The economic value of the crop hasbeen further enhanced due to its high com-mercial value in the world spice industry (GOV-INDARAJAN et al. 1982, FAO 1990). Thus largetracts of land in the humid tropics are beingcultivated due to the profitability of this cropand its adaptability to sustainable agroforestryconditions (GOVINDARAJAN et al. 1982), a sys-tem of land use recommended for these regions(SGHOUTEN 1986).

Traditionally, cardamom has been propa-gated by segments of rhizomes obtained fromhealthy plants (PuRSEGLOVE et al. 1981). Withincreased demand for good quality plantingmaterial, seed propagation is being adopted inmany regions (GOVINDARAJAN et al. 1982).Howev ,r, cardamom seeds are consideredrecalcitrant (KiNG and ROBERTS 1979, SAN-GAKKARA 1990), due to the relatively highmoisture content at maturity and poor stor-ability. Thus, cultivation practices are oftenhindered by the lack of suitable plantingmaterial.

The popular varieties of cardamom cultivatedin the Asian humid tropics are Mysore, Malabarand Vazukka (GOVINDARAJAN et al. 1982).These varieties are extensively used in planting

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52 SANGAKKARA

programmes in all regions. However, com-parative studies on seed characteristics, ger-mination and storage behavior of seeds of thesevarieties which are important in propagationhave not been reported, although earlier studies(e.g. SANGAKKARA 1990) identified relation-ships between storage and germination of onevariety of this important spice crop. Thus, theobjectives of this study were to determine andcompare the pod and seed characteristics ofthe Mysore, Malabar and Vazukka varietiesof cardamom, along with germination and theresponse of seeds to desiccation in terms ofmaintaining viability.

Materials and MethodsMature {both green and yellow maturity stages) podsof cardamom varieties (Mysore, Malabar andVazukka) harvested from the research station of theDepartment of Export Agriculture, Matale, SriLanka, were transported on the same day to the CropScience laboratories of the University of Peradeniya,Sri Lanka. These were stored at 5 °C overnight. Theexperiments were initiated within 24 h of trans-portation.

Experiment 1: Evaluation of pod, seed and ger-mination characteristics of cardamom

Green and yellow mature pods of all varieties weresorted manually based on husk colour. From eachmaturity group, five replicates of 30 pods wereweighted and dried at 80 °C for 48 h to determine themoisture contents gravimetrically. Seeds were alsoremoved from five replicates (25 pods per replicate)of the two maturity groups in each variety for thedetermination of seeds per pod, 100 seed weight andmoisture contents.

Seeds were also extracted from 30 capsules of eachmaturity group of the three varieties. Each lot wasdivided into four replicates each containing 80 seeds.These lots were soaked in 25 % nitric acid for scari-fication of the hard seed coat and washed in flowingwater as recommended by the Department of ExportAgriculture, Sri Lanka (1981). The scarified seed weredusted with a fungicide (Serasan 40 % EC), plantedin sand trays to a depth of 1 mm and lightly covered.The trays were covered with black polyvinyi netting,kept at room temperature (27.5 °C ± 2.2 °C) and wat-ered regularly.

The time taken for germination of 40 % of plantedseed was noted along with the final germination per-centage (at 100 days).

Another seed lot was extracted from pods of allvarieties at the yellow stage of maturity. These seedswere manually divided into large and small seedsbased on external appearance. Subsamples of the largeand small seeds were dried at 80 °C for moisture

determination. At the same time, five replicates, eachcontaining 75 seeds of the two sizes of seeds, wereplanted and days to 40 % germination and final ger-mination percentage were determined as describedearlier.

Experiment 2: Influence of drying temperature ongermination of cardamom seeds

Seeds were removed carefully from mature (yellow)pods of the three varieties. These were scarified withnitric acid, dusted with Serasan (40 % EC) and driedat 20 °C or 30 ^C. Subsamples of approximately 100seeds were removed from each category at 2 dayinter\'als up to 15 days. Seed moisture content andgermination was determined in seed lots containing40 seeds obtained from these subsamples using theprocedure described earlier.

The data of both experiments were subjected tostatistical analysis to determine the significance ofobserved differences.

Results and Discussion

The variety Mysore had heavy pods at bothmaturity levels (Table 1). The fresh weights ofVazukka pods were the lowest. However, thefresh weights of pods decreased with increasingmaturity in all varieties (green to yellow), andthis decline was most evident in Mysore. Thedecline in fresh weights was due to the loss ofmoisture. Although Vazukka had the lowestfresh weights of pods, the dry weights were theleast in Malabar due to the very high moisturecontent of the former variety^ However, thedry weights of Mysore were the highest.

Pod dry weights were higher in the moremature (yellow) pods, which indicated thegreater accumulation of dry matter betweenthese two stages of maturity. The differenceswere again most evident in the Mysore variety(6 %) when compared to Malabar (3 %) andVazukka (0 %). Thus, harvesting pods at thefully mature stage would ensure a greater yield,especially in the Mysore variety.

The variety Mysore has a greater number ofseeds per pod, while that of other two varietieswere similar. Thus, seed numbers which aredetermined soon after pollination (PURSE-GLOVE et al. 1981) did not increase with matur-ity. The Mysore variety also had heavy seeds,while those of Malabar were the lightest asdetermined by 100 seed weight. There was amarginal increase in seed weight due to matur-ity, which was greater in Mysore than in theother two varieties, although the differenceswere not significant.

Pod, Seed and Germination Characteristics of Cardamom 53

Table 1. Pod and

Variety

A: PodsMysore

Vazukka

Malabar

B: Seeds

Mysore

Vazukka

Malabar

C: Germination

Mysore

Vazukka

Malabar

seed characteristic!

Pod type

GreenYellowGreenYellowGreenYellow

GreenYellowGreenYellowGreenYellow

GreenYellowGreenYellowGreenYellow

Fresh

859836674658725714

Seed

16.816.514.514.414.114.0

; of selected cardamom varieties

wt (mg)

±20.6± 14.1± 15.4± 10.5±7.3± 15.3

is/Pod

± 1.8±0.7±0.4±0.2±1.1±0.7

Dry wt (mg)

268 ± 12.6285 ±9.5236 ±9.1235 ± 11.7205 ± 15.5212 ±6.9

100 Seed wf''"(mg)

942 ± 15.3947 ± 10.3864 ± 7.5867 ± 6.2829 ± 11.3832 ± 7.5

Days to 40 % Germination

54 ± 1.552 ±2.159 ± 1.856 ± 3.056 ± 0.655 ± 1.4

% H,O-^

68.8% ±3.2965.9% ±2.1365.4% ±5.9864.1% ±2.1671.7% ±4.487 0 . 3 % ± 3 . 2

% H2O'-'

75.8% ±2.471.5% ±1.671.5% ±3.869.4% ±2.974.1% ±3.170.6% ± 1.8

% Germination(Final)

61.3 ±2.878.4 ± 3.556.5 ±3 .967.1 ±2.258.7 ± 1.768.5 ±4 .0

"" 100 seed wt after drying'•'"' Seed moisture content at harvest

Seed moisture content of varieties at maturitywere very high, thus illustrating the recalcitrantnature of cardamom seeds (KING and ROBERTS1879, SANGAKKARA 1990). The highest seedmoisture contents were in the Mysore and Mal-abar varieties. Vazukka, which is a naturalselection of traditional Mysore and Malabarvarieties (GOVINDARAJAN et al. 1982), had thelowest seed moisture content. Increasingmaturity lowered seed moisture content, whichagain has a deterministic effect on yields. TheMysore variety of cardamom is considered tobe high yielding (SAMARAWIRA 1972, GOV-INDARAJAN et al. 1982), with large pods. Thisphenomenon is observed in the present study,and the greater yields of this variety could beattributed to a greater number of heavier seedsin larger pods.

All varieties of cardamom germinated within

40 days, and reached a 40 % germination within50—60 days. The Mysore variety achieved a40 % germination earlier than other varieties(53 days), while Vazukka took the longest time(57 days). While these differences are notsignificant, other methods of scarification mayillustrate greater variations. However, theMysore variety bad the highest germinationpercentage, irrespective of maturity stage. Thefinal germination of the other two varieties weresimilar, and lower than in Mysore. Increasingmaturity enhanced germination of cardamom,irrespective of the variety. Thus, pods requiredfor seed purposes should be harvested at fullmaturity (yellow stage) rather than at earlierstages, when the crop is generally harvested toobtain a greater number of pods.

Seed characteristics of the three varieties arepresented in Table 2. The large seeds are heavier

54 SANGAKKARA

Table 2. Seed and germination characteristics of selected cardamom varieties'

Variety Seed Type 100 Seed wt (mg) %

Days to40%Germination % Germination (Final)

Mysore

Vazukka

Malabar

LargeSmallLargeSmallLargeSmall

1132 ± 14.2801 ±9.7926 ± 7.4741 ±4.9

865 ± 10.1772 ± 6.5

70.675.170.574.371.476.3

/o

/o

/o

/o

/o

/o

42 ± 4.257 ±3.249 ±4.162 ±2.956 ±3.669 ±2.2

71.4 ±3.646.5 ±4.368.2 ± 1.843.8 ±3.061.4 ±2.642.9 ± 5.2

Seeds obtained from yellow ripe pods.

(41 % in Mysore, 28 % in Vazukka and 12 %in Malabar). Small seeds have a greater per-centage of moisture, which suggests immatur-ity. This also indicates that seed within acardamom pod does not mature at the sametime. Large seed would thus have a greaterquantum of stored material, which results inearlier germination of greater numbers (Table2). Thus the time taken by the larger seeds toachieve a 40 % germination was lower (15, 13and 7 days in Mysore, Vazukka and Malabarvarieties). Furthermore, a greater number oflarge seeds germinate. Thus, the often reportedpositive relationship between larger seeds andearly germination for other crops (FAGERIA

1992) is also observed in this important tropicalspice crop. The lower germinability of smallseeds could be due to the higher moisturecontent, immaturity and the lack of sufficientfood reserves for germination. Thus, plantingprogrammes need to use large seeds to obtaingreater numbers of propagules.

Cardamom seeds lose germinabihty rapidly,with desiccation (Fig. 1), when the seed moist-ure content falls below a critical level. Thisagain is a feature of recalcitrant seeds (KING andROBERTS 1979). In all varieties, germinationis completely lost below 40 % seed moisture,although earlier studies on Mysore (SAN-GAKKARA 1990) reports the absence of ger-mination below 50 % moisture contents.However, the Mysore variety was the mosttolerant to desiccation and maintained ger-minability for a longer period of time whendried at 20 °C. This could be due to its largersttA size. In contrast, the small seeded Vazukkaand Malabar varieties did not survive des-iccation and lost germinability rapidly.

The influence of drying temperature wassimilar in all varieties. Seeds dried at 30 °Glost germinability rapidly, although the trendsobserved at a drying temperature of 20 °C wereseen m the three varieties. Thus, the largerseeded Mysore variety maintained a higher ger-minability than other smaller seeded varieties.This rapid loss of germination when seeds aredried at higher temperatures could be attributedto tissue damage with the rapid removal ofmoisture of these recalcitrant seeds (AKARODA

1984).

Conclusion

Fresh weights of pods in three popular varietiesof cardamom declined with maturity due to theloss of moisture, while dry weights increased.Thus greater yields could be obtained by har-vesting fully mature seeds, although this may bemore expensive in terms of labour for selectiveplucking.

Cardamom seeds have a very high moisturecontent at maturity, thus illustrating their recal-citrant nature. The Mysore variety has largerpods with greater numbers of seed. The Mal-abar variety has small pods with seed numberssimilar to that of Vazukka. Seed weights ofMysore are greater, and these germinate earlier.Germinability of seeds of all varieties increasedwith maturity. Thus, seeds for propagationneed to be obtained from fully matured pods.

Large seeds of all varieties germinate earlierin greater numbers. This again is important inselecting seeds for propagation. Small seedswith high moisture contents do not germinatewell.

Pod, Seed and Germination Characteristics of Cardamom 55

Mysore

60 T

ra

I 40u

S. 30 +20

10

0

Germination

MoistureC20''c)

•

Vazukka

13

Malabar

Moisture (2O''c)

Germination (2O'c)

13

Days

80

70

60

50

40

30

20

10

0

•• 80

• 70

•• 60

• 50

• 40

- 30

• 20

• 10

- • 0

Figure 1. Effect of drying temperatures on moisture content and germination of cardamom seeds

Seeds of cardamom do not withstand des- temperatures to retain germinability for someiccation, especially at high temperature. Thus, time. While Mysore seeds could withstand des-if required, seeds should be dried at very low iccation to a greater extent, which could be

56 SANGAKKARA

due to its seed size, germination could not bemaintained beyond 9 days.

Cardamom varieties have been identified byselection. Thus, while Mysore, which is con-sidered a high yielding variety, has superiorseed characteristics and germinability, therelationships between seed size, moisture con-tents, germination and response to desiccationof all varieties to desiccation were similar. Thus,for propagating purposes, large seeds need tobe obtained from fully matured pods and ger-minated without delay. If desiccation isrequired, this should be at low temperatures(such as those under shade) and planted as soonas possible.

Zusammenfassung

Eigenschaften der Kapsel, des Samens undder Keimung von ausgelesenen Kardamom(Elettaria cardamomomum (Linn.) Maton)Sorten

Kardamom lst ein bekanntes und bedeutendestropisches Gewurz, dafi traditionell durch Rhi-zome vermehrt wird, obwohl auch die Samen,die als schwer keimfahig gelten, zunehmend inBestellungsprogrammen verwendet werden. Inden nachstehenden Untersuchungen sollen dieEinfliisse der Kapselreife auf die Kapsel, denSamen und Keimungseigenschaften von 3 ver-breiteten Sorten zusammen mit dem Einflufder Trocknung auf die Keimfahigkeit unter-sucht werden. Grune und gelbe reife Kapselnund Samen aller Sorten wiesen einen hohenFeuchtigkeitsgehalt auf. Die Sorte Mysore, dieals hoch ertragreich gilt, hat grofie Kapseln miteiner hoheren Anzahl von schweren Samen.Obwohl die Kapseln von Vazukka als Folgeeines hoheren Samengeswichtes schwerer sindals die der Sorte Malabar wurde eine ver-gleichbare Anzahl von Samen in beiden Sonengefunden. Der Feuchtigkeitsgehalt der Samennahm mit zunehmender Kapselreife ab, wah-rend die Samengewichte und die Keimfahigkeitzunahmen. Die Keimfahigkeit der Samen vonMysore war hoher im Vergleich zu den anderenSorten. Die grofieren Samen aller Sorten keim-ten 15—20 Tage fruher, woraus sich ein grofi-erer Anteil (20—25 %) von Samlingen ergab.Eine Trocknung bei 20 °C erhielt die Keim-fahigkeit fiir einen langeren Zeitraum (5—9Tage) bei alien Sorten im Vergleich zu einerTrocknung bei 30 ""C. Die Samen der Sorte

Mysore waren toleranter gegenuber einerTrocknung als die der anderen Sorten. DieUntersuchung zeigt die Bedeutung der Aus-wahl grower Samen aus gelben reifen Kapselnvon Kardamom fiir die Vermehrung und denWert einer Verwendung unmittelbar nach derErnte, um eine grofiere Anzahl von Samlingenzu erhalten.

Acknowledgements

Gratitude is expressed to the Research Officer inCharge of the Cardamom research unit of the Depart-ment of Export Agriculture for the provision of seedsand Mr E. R. PIYADASA and Ms A. M. U.

ATTANAYAKE for research assistance. The facilitiesprovided by Prof DrJ . NOSBERGER, Institute of PlantSciences, ETH, Zurich, Switzerland for compilingthis paper is acknowledged.

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