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Seed germination studies on Gymnacranthera canarica (King) Warb. - a Vulnerable tree species of a highly threatened Myristica swamp ecosystem K. Keshavachandra 1 & G. Krishnakumar 2 Department of Applied Botany, Mangalore University, Mangalagangothri, Karnataka 574199, India
[email protected] , 2
[email protected] (corresponding author)
1,2 1
Abstract: Gymnacranthera canarica (King) Warb. is an exclusive Myristica swamp species endemic to the Western Ghats. The Myristica swamp is a Critically Endangered ecosystem. Studies were carried out to assess the viability, germination and storage behaviour of Gymnacranthera canarica seeds. In the present study, it was observed that seeds have shown an initiation of germination after two weeks. A maximum of 90% germination was recorded when the initial moisture content was 38.04 ± 1.75 %. A decreased percentage (3%) was observed when the moisture content reached 14.26 ± 2.3 after 70 days of storage. Seeds failed to germinate beyond this moisture level. A desiccation study showed recalcitrant behaviour and seeds can be stored in lab conditions for up to two and half months. Keywords: Gymnacranthera canarica, germination, moisture content, Myristica swamps, polyembryony, seed storage, viability.
The genus Gymnacranthera Warb. belongs to the family Myristicaceae with seven species in the IndoMalayan region (Mabberly 1987). Gymnacranthera canarica (King) Warb. is an endemic and Vulnerable tree species (WCMC 1998) exclusively found in Myristica swamp ecosystems of evergreen forests in the Western Ghats. The Myristica swamp ecosystem was first reported by Krishnamoorthy (1960) from Kulathupuzha region of the Western Ghats, Kerala, which is a forest patch in the perennial swampy regions in the evergreen forests dominated either by Gymnacranthera canarica (King) Warb. or Myristica fatua Houtt. var. magnifica
ISSN 0974-7907 (Online) ISSN 0974-7893 (Print)
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(Bedd.) Sinclair. or both. These trees possess a modified root system, knee roots (Image 1A) with prominent lenticels on the surface for respiration in order to survive in the swamp. These ecosystems are virtually living museums of ancient life. These relic forests are often considered as ancient forest patches (Chandran et al. 2010). Champion & Seth (1968) classified this type of vegetation patch as tropical fresh water swamp forests (4C/FSI). The occurrence of swamps depends on non biotic conditions like flat bottomed or gently sloping valleys in between heavily forested hills, deep soil in the adjoining hills with rock allowing water storage above the rock layer, slow and continued water seepage into the valley and an average of 3,000mm rain fall (Chandran et. al 1999; Varghese et al. 1999; Nair et al. 2007). Hence, these swamps are highly restricted in distribution and occurrence and are considered as critically endangered ecosystems (Roby et al. 2014). The seed of Gymnacranthera conforms to the fruit with testa and bright red coloured aril (Image 1B). Seeds are used in the manufacture of candles (Gamble 1921). Seeds contain much fat, which is probably an adaptation for dispersal and survival under swampy conditions (Tambat et al. 2007). The present study was made to
DOI: http://dx.doi.org/10.11609/jott.2152.8.7.9009-9013 Editor: A.J. Solomon Raju, Andhra University, Visakhapatnam, India.
Date of publication: 26 July 2016 (online & print)
Manuscript details: Ms # 2152 | Received 16 July 2015 | Final received 20 May 2016 | Finally accepted 03 July 2016 Citation: Keshavachandra, K. & G. Krishnakumar (2016). Seed germination studies on Gymnacranthera canarica (King) Warb. - a Vulnerable tree species of a highly threatened Myristica swamp ecosystem. Journal of Threatened Taxa 8(7): 9009–9013; http://dx.doi.org/10.11609/jott.2152.8.7.9009-9013 Copyright: © Keshavachandra & Krishnakumar 2016. Creative Commons Attribution 4.0 International License. JoTT allows unrestricted use of this article in any medium, reproduction and distribution by providing adequate credit to the authors and the source of publication. Funding: UGC Major Research Project No.: F.No.39-376/2010 dated 6-1-2011. Conflict of Interest: The authors declare no competing interests.
LOGOs
Acknowledgements: We thank University Grants Commission for the financial assistance in the form of a major research project.
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Journal of Threatened Taxa | www.threatenedtaxa.org | 26 July 2016 | 8(7): 9009–9013
Seed germination studies on Gymnacranthera canarica
Keshavachandra & Krishnakumar
© K. Keshavachandra
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Image 1. (A) Myristica swamp - Knee Roots; (B) Gymnacranthera seeds with aril; (C) Seeds without arils; (D) Experimental set up - seeds sown on sand bed; (E) Polyembryony: Twin seedlings with separate roots and shoots
assess the germination behaviour, storage and viability in seeds of Gymnacranthera canarica. Materials and Methods Seeds of Gymnacranthera canarica (King.) Warb. were collected from the Myristica swamp forest in Belthangady Taluk of Dakshina Kannada District, Karnataka in August 2012. The aril was removed from the collected seeds (Image 1C) and washed with water. Seed samples without any insect infestation and physical damage were selected for the experiment. To assess the viability and germination behaviour, initially the seeds were sown in a sand bed twice with 10 days interval. Later, they were sown at an interval of five days up to 100 days in two replicates. Sixty seeds were taken in each experiment. The remaining seeds were used to test moisture content and for a viability test. Germination test The germination percentage was determined by using the standard sand bed method (International Seed Testing Association 1985). Sand was taken in clean plastic trays of required size. The seeds were pressed onto the surface of sand; seeds were placed at a distance of 4 cm on the sand bed (ISTA 1991). Seeded sand beds were watered daily. Germination was scored on the emergence of radicle (2cm in length) and the results are expressed as percentage of seeds germinated 9010
(Image 1D). Seed viability Seed viability was evaluated by taking seeds randomly from the seed lot, treating dissected seed with embryo with 1% 2, 3, 5 - triphenyl tetrazolium chloride solution (TZ) for 17 hours in darkness (ISTA 1999). Moisture content The Moisture content (MC) of the whole seed was determined following a low constant oven drying method (ISTA 1991). Randomly selected seeds were cut into pieces of definite quantity (5g). Then dried at 1030C for 17 hours in a hot air oven. This experiment was done in triplicate. Seed MC was calculated on a fresh mass basis. M 2 – M3 Moisture percentage = –––––––– x 100 M 2 – M1 M₁ - is the weight of Petri plates; M₂ - is the weight of Petri plates with seeds before drying; M₃ - is the weight of Petri plates with seeds after drying. Desiccation study After procuring the seeds, clean and pure seeds were selected for the study. The initial fresh moisture content of the seeds was first determined using the above method; viability is checked by the Tetrazolium test
Journal of Threatened Taxa | www.threatenedtaxa.org | 26 July 2016 | 8(7): 9009–9013
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Ob se r v afion s
P e r cen ft a g e(% )
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F fi r s ft fle a ffo c cu r r ed
14 –59d a y s(2 –8w e e k s )
53 –68d a y s(7 –9w e e k s )
Mo fi s ftu r e
100 90 80 70 60 50 40 30 20 10 0
G e rm fin afion
1
10
20
25
30 35 D a y s
40
45
50
70
F fi gu r e1 .Ge rm fin afionpe r cen ft a g eand mo fi s ftu r econ ft en ft fin G ymna c ran fth e racana r fi ca
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andfth es e ed sw e r ed e s fi c c a ft edupfto10 –12% mo fi s ftu r e con ft en ft(Hon g&E fl fl fi s1996 ) .D e s fi c c afionw a sp e r ffo rm ed b ym fi x fin gequ a flamoun ft so ffs e fl fffind fi c afin gs fi fl fi c ag e flfin g fl a s sd e s fi c c a fto r s .Th es e ed sw e r em fi x edftw fi c ead a yfto g e ftp rop e ra e r afion( IPGR I2000 ;V a r gh e s ee fta fl .2002 ) . Th ed a ft aob ft a fin edons e edg e rm fin afionw a su s ed ffo rfth e ffo fl flow fin gp a r am e ft e r s .
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1
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fine a r fl fi e rs ftud fi e sa fl sob yT amb a fte fta fl .(2006 ) .Th fi sfi s aft r fibu ft edftofth ep r e s en c eo ffd eh yd ro g en a s een z ym e fin fth eo fth e rfl fi v fin gc e fl fl sfinfimm a ftu r es e ed swh fi chr edu c e s 2 ,3 ,5ft r fiph en y flft e ft r a zo fl fiumch flo r fid e ,ffo rm fin gb r fi gh ftr ed , s ft ab fl e ,ft r fiph en y flffo rm a z an . Th e s efimm a ftu r es e ed sff a fi fl ftog e rm fin a ft e .I ftfi sa fl sopo s s fib fl efins e ed sfin ff e c ft edw fi fth ffun g fiwh fi chr e a c ftw fi fthft e ft a r zo fl fiumffo rm fin gar edco flou r (R .K .M fift a flp e r s .comm .1997 ) . In fifi a fl mo fi s ftu r econ ft en fto fffth es e edw a s38 .04±1 .7 % wh fi ch w a ss fi gn fifi c an ft fl yd e c r e a s edonfth e10fthd a y (28 .82±1 .56% ) . As ft e ad yd e c r e a s efinfth e mo fi s ftu r e fth con ft en ftw a sob s e r v edonsub s equ en ftd a y s .Onfth e50 d a yfth e mo fi s ftu r econ ft en ft w a s16 .44±2 .57 % . Wh en fth e MCcon ft en ftr e a ch ed14 .26±2 .3( s e ed sk ep ftaft e r70 d a y so ffs fto r a g e ) ,fth e r ew a snog e rm fin afion . On fl y ,on e s e edg e rm fin afion w a sob s e r v edonfth es e ed ssownon
Jou rn a flo ff T h r e a ft enedT a x a|www . fth r e a ft en ed ft a x a .o r g|26Ju fl y2016|8 (7 ) :9009 –9013
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Seed germination studies on Gymnacranthera canarica
Keshavachandra & Krishnakumar
Table 2. Deterioration in seed germination, germination energy and germination speed index of Gymnacranthera canarica (*p
