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8. improved germination of gymnacranthera canarica warb. an


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8. improved germination of gymnacranthera canarica warb. an

  1. 1. 625 IMPROVED GERMINATION OF GYMNACRANTHERA CANARICA F O R M A T T E D P R O O F Tambat, B., Vishwanath, K., Chaithra, G.N. and Hareesh, T.S. (2006), Seed Sci. & Technol., 34, 625-630 Improved germination of Gymnacranthera canarica Warb. an endangered, endemic tree species of Myristica swamps, Western Ghats, India B. TAMBAT1 , K. VISHWANATH2 , G.N. CHAITHRA3 AND T.S. HAREESH4 1 Department of Crop Physiology and University of Agricultural Sciences, Bangalore, India 1 (E-mail: 2 Department of Seed Science and Technology, University of Agricultural Sciences, Bangalore, India 3 College of Forestry, Sirsi, Uttara Kannada, Karnaraka, India 4 Bio-Science Department, University of Mysore, Hemagangothri, Hassan, Karnataka, India (Accepted April 2006) Summary Gymnacranthera canarica Warb, an endangered, endemic tree species of Western Ghats, India. The species is exclusively associated with swampy conditions and habitat destruction seems to be the major threat. Although seed viability was 98 per cent confirmed by TZ test, initial germination was only 40% suggesting dormancy problem in this species. Among the 14 treatments, seed coat removal itself enhanced germination by 20 per cent (60%) over control (40%) showing partial permeability of seed coat to water. GA3 @ 50,100 and 250 ppm with partial removal of seed coat showed significantly higher germination by 39, 33 and 30 per cent respectively over control. However, higher concentration of GA3 @ 500 ppm showed inhibitory effect (10%). With respect to IAA we fail to observe any pattern in this species. Further, nil germination in boiling water, cold, boiling water+ hormonal treatment confirming the dormancy of seeds. Our results provide means to enhance the seed germination and helps for restoration and conservation of an endangered species in Western Ghats. Introduction Gymnacranthera canarica Warb. is one of the threatened tree species (IUCN, 2002) that is associated with swampy habitat in the Western Ghats, a global mega diversity hot spot in India (Myers et al., 2000). It belongs to family Myristicaceae (or nutmeg), a family one among the primitive flowering plants and mostly known for its mace and seeds, which are of high medicinal importance (Purseglove et al., 1981; Yoganarasimhan, 2000). The fruits are globose with thick and fleshy pericarp. The seed conforms to the fruits, testa woody with bright red colored aril (Gamble, 1935). The seeds contain much fat, probably as an adaptive mechanism for dispersal and survival under swampy conditions. In past few decades due to conversion of swamps into areca gardens and diversion of water for agricultural purpose, regeneration and survival of G. canarica is drastically affected (Chandran et al., 1999; Chandran and Mesta, 2001; Tambat et al., 2004). The field study by Tambat et al., (2004) has demonstrated that species is exclusively associated with swampy conditions with few meters away from the swamps the species disappear. Thus,
  2. 2. 626 B. TAMBAT, K. VISHWANATH, G.N. CHAITHRA AND T.S. HAREESH F O R M A T T E D P R O O F habitat destruction, which influences the local microclimate, could be one of the major cause for reduced germination and survival of G. canarica. As for as seed germination is concerned the species possess hard seed coat and shown lower germination under nursery conditions (unpublished). It is likely that the species may have seed coat induced dormancy, as observed in few forest species (Naidu et al., 2000; Tigabu and Oden, 2001). The present study aims to assess the effective seed treatment that would enhance seed germination under laboratory conditions and thereby facilitate conservation of G. canarica an endangered tree species through re-introduction or enrichment planting. The reintroduction of species in to its natural habitat is one of the best strategies for the conservation of critically endangered endemic species, as it would act as a functional bridge between the ex situ and in situ conservation methods (Frankel et al., 1995). Materials and methods Mature seeds of Gymnacranthera canarica Warb. were collected from Kathlekan forest, Siddapura range (14° 16' 250, 74° 44' 880) of Uttara Kannada in Karnataka during October and November 2004. The seeds were washed in water and bulked before imposing any treatment. The seed viability was confirmed by following 2,3,5-Triphenyl Tetrazolium Chloride (TTC) test using randomly selected 300 seeds of 100 seeds in each replications from the seed lot (Agrawal and Dadlani, 1995). The seeds were allowedto germinate in pots containing sand under ambient conditions, as Bhat and Kaveriappa, (2002) have shown better germination by sand method than blotter in laboratory condition (25-28°C) in Gymnocranthera farquhariana Hook. (Synonymous with Gymnacranthera canarica Warb., Gamble 1935). Totally 14 treatments were imposed including control with three replications of 50 seeds and details as follows; (1) Control (without any treatment), (2) Entire seed coat removal, (3) Diaphragm aperture + GA3 @50 ppm (16hrs), (4) Diaphragm aperture + GA3 @100 ppm (16hrs), (5) Diaphragm aperture + GA3 @250 ppm (16hrs), (6) Diaphragm aperture + GA3 @500 ppm (16hrs), (7) Diaphragm aperture + IAA @50 ppm (16hrs), (8) Diaphragm aperture + IAA @100 ppm (16hrs), (9) Diaphragm aperture + IAA @250 ppm (16hrs), (10) Diaphragm aperture + IAA @500 ppm (16hrs), (11) Boiling water (100°C for 15 sec), (12) Boiling water (100°C for 15 sec)+ IAA @100 ppm (16 hrs), (13) Boiling water (100°C for 15 sec) + GA3 @100 ppm (16 hrs) and (14) Cold (-12°C for 12 hrs). The number of seeds germinated was recorded by taking out the seedling from the sand bed. Per cent germination was computed based on normal seedling basis. The data of germination was subjected to arcsin transformation for statistical analysis. Following Completely Randomized Design (CRD) and adopting “Fischer’s Analysis of Variance Technique” critical difference values were calculated at 5 per cent probability level (where “F” test was significant). Dunnett’s “t” test was then performed to compare control with all other treatments (Panse and Sukhatme, 1967).
  3. 3. 627 IMPROVED GERMINATION OF GYMNACRANTHERA CANARICA F O R M A T T E D P R O O F Results and discussion From Tetrazolium test it was confirmed that viability of seeds selected for imposing dormancy treatments was 98 per cent and were showed deep red embryonic axis and cotyledons. Only two per cent of seeds were showed unstained embryonic axis and pale red staining with unstained areas in cotyledons. However, we could observe only 40 per cent germination under ambient condition, emphasizing the presence of dormancy in these seeds. Pre sowing treatments have been shown to enhancing seed germination in many species (Kattimani et al., 1999; Pandey et al., 2000; Joshi and Dhar, 2003). The effect of seed treatment on germination of Gymnocranthera canarica after four months has been shown in figure 1. Per cent germination of seeds with 14 treatments varied from 0 to 79 per cent. As for as improved germination, seed coat removal alone increased the germination by 20 per cent indicating the partial permeability of seed coat to the water. Such results were also noticed by Naidu et al., (2000) in Sapindus trifoilatus and Tigabu and Oden, (2001) in Albizia sp. The application of GA3 along with partial seed coat removal further enhanced the germination (40% over control). However, the per cent germination varied with the concentration of GA3; we observed maximum germination (79%) in seeds treated with 100 ppm GA3 then that of other treatments (i. e. 73 % @ 50 ppm and 70% @ 250 ppm). Forest species are known to contain certain inhibitory compounds in seed coat and (or) Figure 1. Mean seed germination (%) as influenced by the treatment in Gymnacranthera canarica. (Note: Hormonal treatments was imposed by soaking the seeds in different concentrations of hormone solution after diaphragm aperture / partial removal of seed coat for 16 hours). * 1 - Significantly superior over control * 2 - Significantly inferior over control NS - Non significant over control 0 10 20 30 40 50 60 70 80 90 Control Entireseedcoatremovel HormoneGA350(16hr) HormoneGA3100(16hr) HormoneGA3250(16hr) HormoneGA3500(16hr) HormoneIAA50(16hr) HormoneIAA100(16hr) HormoneIAA250(16hr) HormoneIAA500(16hr) Boilingwater(100oC-15sec) Bolingwater+IAA100 Bolingwater+GA3100 Cold(-12oC-12hrs) MeanGermination(%) LSD(P<0.05): 6.83 * 1 * 1 * 1 * 1 * 2 * 2 NS * 2 NS * 2 * 2 * 2 * 2
  4. 4. 628 B. TAMBAT, K. VISHWANATH, G.N. CHAITHRA AND T.S. HAREESH F O R M A T T E D P R O O F endosperm, which affects the germination process; external supply of GA3 neutralizes such effect and facilitates germination (Evenari, 1949; Mary, 1972). Earlier studies on forest species have showed GA3 enhanced seed germination in Cassia (Padma et al., 1996), Annona squomosa (Pawshe et al., 1997), Pittosporum floribundum (Subodh et al., 1998), Echinacea purpurea (Kochankov et al., 1998), Albizia sp. (Tigabu and Oden, 2001), Arbatus andrachne (Karam and Al-Salem, 2001). However, germination was reduced drastically to 10 per cent as GA3 concentration increased to 500 ppm, which may possibly due to imbalanced cell activity or toxic effect of GA3 at higher concentration (Takashashi et al., 1991; Deno, 1993). Such results were also noticed by Naidu et al., (2000) in Sapindus trifoliate, Tigabu and Oden (2001) in Albizia sp. and Karam and Al-Salem (2001) in Arbutas andranchne. Indole acetic acid (IAA) a phyto-hormone which is also known to enhance the germination in certain species such as Aleurites fordii (Chatterjee, 1960), Hibiscus esculent (Omran et al., 1980) and Sapindus trifoliates (Naidu et al., (2000). However, in the present study irrespective of concentrations gradient we fail to observe such enhanced germination. IAA @ 100 and 500 ppm the germination was found to be on par with the control, where as IAA @ 50 and 250 ppm there was significantly lower germination than that of control. Since, there is no clear pattern we feel there is a need to understand the role of IAA in Gymnocranthera canarica during germination with further studies. Other treatments such as boiling water, cold, boiling water along with hormones showed nil germination and were found to be significantly inferior over control. No germination also indicates dormancy problems in this species. These results might also indicate temperature sensitive of the species which is reported in Myristica malabarica Lam. a close relative of G. canarica (Anil Kumar et al., 2002). Thus, in this regard further studies are needed. In conclusion, Gymnacranthera canarica is an obligatory swampy species thus may contain certain inhibitory compounds in the seeds, which are leached out due to the continuous flow of water in the natural swampy habitat. Now, due to anthropogenic activity the natural habitats have been disturbed thus natural germination process is affected. With regards to improved germination our results indicate that seed germination can be enhanced up to 79 per cent using GA3@100ppm with partial removal of seed coat. In the present scenario our results provide an alternative means to enhance the seed germination, thus helps in conservation and restoration of a habitat specific, endemic and endangered tree species of the Western Ghats, India. For the purpose of enrichment planting, development of seedlings through seeds is known to be best method as it is cheaper and also helps to maintain the natural genetic variability among the planting material (Tilki, 2004). Acknowledgements We would like to thank Mr. P.G. Suraj, Dr. R. Vasudev, Mr. I. Sriram and students of College of Forestry, Sirsi for the technical support during the fieldwork. We acknowledge Karnataka Forest Department for the permission and British Petroleum (BP), UK for the financial support.
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