Objective: This study was conducted to investigate the mycorrhizal colonization and biomass productivity of different sites of Pongamia pinnata nurseries plant. Methodology: The rhizosphere soil and root samples were collected from five different study sites. Indigenous AMF inoculums supplied 30 g per plant. After 90th days of treatment, plants samples were drawn and observations were recorded. Results: Percentage of Arbuscular Mycorrhizal (AM) infection, number of resting spores and AM fungi (AMF) species varies in different sites of nurseries. The AMF inoculums treatments promising data were observed almost in all study sites for 90th Days After Seedlings (DAS). This variation is attributed to various factors such as mycorrhizal status and biomass. Glomus species dominated in all sites followed by Sclerocystis, Gigaspora and Acaulospora. Conclusion: Mycorrhizae could contribute substantially to achieve better results for high oil seed production. When AMF are more colonized to plants then enhanced the biomass productivity.
PDF Abstract XML References Citation
How to cite this article
Karanj (Pongamia pinnata (L.) Pierre), a fast-growing oil-seed-producing tree legume has the ability to grow on wastelands. It belongs to Fabaceae family. Karanj tree is a wonderful tree almost like neem tree. It can be utilized for biofuel plantation on such lands. The pre-conditioning of young seedlings during the early stage of development with efficient Arbuscular Mycorrhizal Fungi (AMF) confers several benefits enhancing the possibility of their establishment in fields after out planting from nurseries. It has been found as a suitable option for biodiesel production1. It is a fast-growing nitrogen fixing tree legume with the potential for high oil seed production (seed contains 30-35% oil). Pongamia pinnata has the ability to grow on wastelands2 and hence can be utilized for biofuel plantation on such lands (47.22 million ha)3.
The AMF is ubiquitous group of fungi4. The AMF belongs to phylum Glomeromycota5. The general consensus is that AMF improve phosphate nutrition of legumes, which in turn enhances plant growth and nitrogen fixation6. The AMF have been shown to differentially colonize plant roots, causing a variety of effects on plant growth, biomass allocation and photosynthesis7. Increased access to low-mobility soil mineral nutrients has been considered to be the main beneficial effect of AMF on their host plants4. Though late, the importance of AM fungi in nursery management and in revegetation efforts of various types of lands has been realized and of late, it has become an integral part of all stages of afforestation programmes. Therefore, the present investigation was made to productivity and association of mycorrhizae on P. pinnata from different study sites.
MATERIALS AND METHODS
Sample collection sites: The rhizosphere soil and root samples of Karanj (Pongamia pinnata (L.) Pierre) nursery plants were collected during February-May, 2015 in summer season from viz., Naldurg Andur, Jalkot, Osmanabad, Paranda and Kalamb for biomass production and arbuscular mycorrhizal fungal infection status. Ten different replications of rhizosphere soil and root samples were collected in separate ziplock polythene bags from each sites. Soil samples were used for isolation and identification of arbuscular mycorrhizal fungal spores and roots for assessment of percentage root colonization.
Treatments of AMF inoculums to Karanj: Inoculums of indigenous AMF maintained in greenhouse with Coleus (Plectranthus scutellarioides) as host (containing 270-300 spores/100 g soil) was applied 30 g per each plant after 15 days of seedlings of Pongamia pinnata. Seedlings without treatment of AMF are considered as control. The biomass and AMF infection data revealed after 90th days seedling (DAS). Seedlings were watered on alternate days and 10 mL of Hoagland solution twice in a week [Stock solution (1000 mL) (NH4H2PO4, 1 mL, KNO3, 6 mL, Ca(NO3) 2-4 mL, MgSO4 2 mL), micro-nutrients solution (H3BO3, 2.86 g, MnCl2 1.81 g, ZnSO4, 0.22 g, CuSO4, 0.08 g, NaMoO4, 0.02 g)] to each pot, after 90th days of treatment8. Biomass, presence of arbuscules, vesicles, hyphal and Dark Septate Endophyte (DSE) and types of AMF species were monitored; then the root colonization index, i.e., percentage of root length colonized by AMF and spore population in 100 g of soil were calculated.
Biomass production: Pongamia pinnata treated and untreated plants, fresh weight of shoot and roots data were recorded. Shoots and roots were separated and oven dried at 60°C for 48 h for the determination of dry mass after recording their lengths9. Leaf area was measured by disc method. Fifty leaf disc of known size was taken from randomly selected leaves of the plant, discs and remaining leaf blades were oven dried and leaf area was calculated by using equation10:
Area of total leaves (cm2) = No of disc from total leaves×Area of single disc
AMF spore density: One hundred grams of rhizospheric soil was dissolved in 1000 mL of water and decanted through a series of 355-35 μm sieves11. Residues were filtered through Whatman filter paper No. 1 and all spores were counted under the stereo-zoom dissection microscope. Intact and healthy AM fungal spores were mounted in PVLG (Polyvinyl alcohol-lactoglycerol) with and without Melzer×s reagent for identification using keys5 and INVAM (http://www.invam.caf.wvu.edu). The AMF spores were identified up to species level.
Assessment of percentage root colonization: The roots were fixed in to 4% Formalin Aceto Alcohol (FAA). Fixed roots were washed to free FAA cleared in water. Roots are placed in glass vial with 10% KOH and stained in 0.05% trypan blue lactophenol to determine mycorrhizal colonization, these VAM fungal colonized segments studied. Then transferred the sieving on to a gridded petri plate and observed it under the binocular microscope 400X (Lawrence and Mayo LM-52-3521). The percent root colonization was measured by using the equataion12:
Statistical analysis: Statistical analysis of the experiments were performed by using the method described by Mungikar13.
Biomass production: The present study, 10 parameters of biomass productivity was studied in Pongamia pinnata (Table 1). In this study, six replications were used. In biomass production, height of stem (121 cm), width of stem (5.2 cm), length of root (54.8 cm), the number of leaflets was observed more in Kalamb site (74), dry weight of shoot (18.21 g), fresh weight of shoot was found more in Kalamb site (44.7 g) and leaf area (2233.57 cm2) were observed more in Kalamb sites. Fresh weight of root was increased in Osmanabad site (29.41 g) and less in Kalamb (21.6 g). After the AMF inoculums treatments promising data were observed almost in all study sites after 90th Days After Seedlings (DAS). Kalamb site was found good AMF inoculums source of soil.
Mycorrhizal study: Arbuscular Mycorrhizal Fungal (AMF) assessment of percentage root colonization and spore density was studied in Pongamia pinnata (Table 2). Spore density was found more in Andur site (446/100 g soil) and less than Jalkot site (63/100 g soil) followed by Andur site and Paranda site. After treatments of AMF inoculums considerably increased the AMF spore density per 100 g of soil in Paranda site i.e., 63 (334) followed by others. Among AMF spore, Acaulospora rehmii, Glomus macrocarpum, Glomus geosporum, Sclerocystis sp. were observed from all study sites (Fig. 1, 2). The AMF percentage of root colonization was increased in Kalamb site (91.66%), while less Paranda site (70.83%). The AMF root colonization types are Arbuscular (A), Vesicular (V), Hyphal (H), colonization and DSE was found in all sites.
In the literature, there are several reports in which AMF inoculations decreased plant biomass but this decrease has often been found to be transient and reversed later, being followed by a positive growth response14,15. Results also suggested that the extent of growth depression or reduction in P. pinnata varied with inoculated AMF species, which can be related to the variations in carbon demand of different AMF species. It was suggested that such differences in growth response towards different AMF inoculants are directly related to the balance between benefits and costs of the symbioses16. It was examined the mycorrhization level of some important regional plants (Azadirachta indica, Dalbergia sissoo, Dendrocalamus strictus, J. curcas, Leucaena leucocephala, Madhuca latifolia and P. pinnata), which suggested that it was minimum in P. pinnata17. This could be due to the large seeds of P. pinnata and pointed out those plants with large seeds generally exhibit lower AMF densities. It was concluded that AMF inoculations should enhance biomass of P. pinnata only after depletion of metabolic reserves in its cotyledons and such mycorrhizal seedlings can be utilized for biofuel plantation18,19.
|Table 1:||Impact of AMF treatment for biomass production in Pongamia pinnata from different study sites (90 DAS)|
Values means of three replications, values in parentheses are AMF treatment, N: Naldurg, A: Andur, J: Jalkot, O: Osmanabad, P: Paranda, K: Kalamb
|Table 2:||Arbuscular mycorrhizal fungal status in Pongamia pinnata different sites (90 DAS)|
Values represent three replications, Values in parentheses are AMF treatment, A: Arbuscular, V: Vesicular, H: Hyphal, DSE: Dark septate endophytes
|Fig. 1(a-d):||Identified genera of AMF (400X), (a) Acaulospora rehmii, (b) Glomus macrocarpum, (c) Glomus geosporum and (d) Sclerocystis sp.|
|Fig. 2(a-d):||Types of AMF colonization (400X), (a) Vesicles, (b) Hyphal, (c) Arbuscules and (d) DSE and hyphal|
It is relevant to mention that the possible synergistic effect would be the uptake by AM fungal hyphae and translocation into the plant of P released by PSB in soil20-23. Recently, the results showed that the combined inoculation of both PSB, AMF and rock phosphate produced vigorous plant growth of tree seedlings for quick planting24. It was reported that, Azadirachta indica, Pongamia pinnata, Leucaena leucocephala and Acacia catechu were most effective in catching mycorrhizae and can be used as the effective tool in rehabilitation of the degraded ecosystems25.
It was concluded that AMF inoculations should enhance biomass of P. pinnata only after depletion of metabolic reserves in its cotyledons and such mycorrhizal seedlings can be utilized for biofuel plantation. It was also discussed that AMF inoculations when amended enhanced biomass and AMF status of P. pinnata after 90 DAS of treatment. The importance of AM fungi in nursery management and in revegetation efforts has become an integral part of all stages of afforestation programmes. When AMF are more colonized to plants then enhanced the biomass productivity.
|•||Pongamia pinnata is a good source of biofuel|
|•||The AMF inoculations should enhance biomass of P. pinnata only after depletion of metabolic reserves in its cotyledons and such mycorrhizal seedlings can be utilized for biofuel plantation|
|•||Increased access to low-mobility soil mineral nutrients has been considered to be the main beneficial effect of AMF|
|•||The importance of AM fungi in nursery management and in revegetation efforts of various types of lands has been realized and of late, it has become an integral part of all stages of afforestation programmes|
- Karmee, S.K. and A. Chadha, 2005. Preparation of biodiesel from crude oil of Pongamia pinnata. Bioresour. Technol., 96: 1425-1429.
- Scott, P.T., L. Pregelj, N. Chen, J.S. Hadler, M.A. Djordjevic and P.M. Gresshoff, 2008. Pongamia pinnata: An untapped resource for the biofuels industry of the future. Bioenergy Res., 1: 2-11.
- Smith, S.E. and D.J. Read, 1997. Mycorrhizal Symbiosis. 2nd Edn., Academic Press, London, UK., ISBN-13: 978-0-12-652840-4, Pages: 605.
- Cluett, H.C. and D.H. Boucher, 1983. Indirect mutualism in the legume-Rhizobium-mycorrhizal fungus interaction. Oecologia, 59: 405-408.
- Fidelibus, M.W., C.A. Martin, G.C. Wright and J.C. Stutz, 2000. Effect of arbuscular mycorrhizal (AM) fungal communities on growth of Volkamer lemon in continually moist or periodically dry soil. Scient. Hortic., 84: 127-140.
- Alguacil, M.M., E. Torrecillas, Z. Lozano, M.P. Torres, F. Garcia-Orenes and A. Roldan, 2012. Long-term effect of irrigation with water from sewage treatment plant on AMF biodiversity and microbial activities. Geophysical Res. Abstr., 14: 2739-2739.
- Muthukumar, T. and K. Udaiyan, 2000. The role of seed reserves in arbuscular mycorrhizal formation and growth of Leucaena leucocephala (Lam.) de Wit. and Zea mays L. Mycorrhiza, 9: 323-330.
- Gerdemann, J.W. and T.H. Nicolson, 1963. Spores of mycorrhizal Endogone species extracted from soil by wet sieving and decanting. Trans. Br. Mycol. Soc., 46: 235-244.
- Giovannetti, M. and B. Mosse, 1980. An evaluation of techniques for measuring vesicular arbuscular mycorrhizal infection in roots. New Phytol., 84: 489-500.
- Jones, M.D. and S.E. Smith, 2004. Exploring functional definitions of mycorrhizas: Are mycorrhizas always mutualisms? Can. J. Bot., 82: 1089-1109.
- Correa, A., R.J. Strasser and M.A. Martins-Loucao, 2006. Are mycorrhiza always beneficial? Plant Soil, 279: 65-73.
- Li, H., F.A. Smith, S. Dickson, R.E. Holloway and S.E. Smith, 2008. Plant growth depressions in arbuscular mycorrhizal symbioses: Not just caused by carbon drain? New Phytol., 178: 852-862.
- Jin, L., S. Wang, X. Wang and Y. Shen, 2009. Seed size influences arbuscular mycorrhizal symbiosis across leguminous host-plant species at the seedling stage. Symbiosis, 49: 111-116.
- Jha, A., M. Kamalvanshi, A. Kumar, N. Chakravarty, A. Shukla and S.K. Dhyani, 2014. The effects of arbuscular mycorrhizal inoculations and cotyledon removal on early seedling growth of Pongamia pinnata. Turk. J. Bot., 38: 526-535.
- Garbaye, J., 1991. Biological interactions in the mycorrhizosphere. Experientia, 47: 370-375.
- Lakshman, H.C., 2009. Growth response and nitrogen fixation of Phaseolus lunatus (Lima bean) with the inoculation of AM fungi and Rhizobium. Asian Sci., 4: 37-41.
- Kumar, A., R. Raghuwanshi and R.S. Upadhyay, 2010. Arbuscular mycorrhizal technology in reclamation and revegetation of coal mine spoils under various revegetation models. Engineering, 2: 683-689.