1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)

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Subject: search.filters.subject.Forest Resource Management

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    Monitoring and evaluation of forest canopy density model in Nilambur forests, Kerala using geospatial techniques
    (Department of Forest Resource Management, College of Forestry,Vellanikkara, 2025) Ajay Antony.; Srinivasan, K
    The study entitled ‘Integrated management of Fusarium wilt of yard long bean in homesteads’ was undertaken at College of Agriculture, Vellayani and Integrated Farming System Research Station (IFSRS), Karamana during 2023-25 with an objective to develop an integrated management package for the vascular wilt of yard long bean incited by Fusarium oxysporum using bioagents and biofumigants in homesteads. The culture of F. oxysporum (accession no: MZ706472.1) maintained at IFSRS, Karamana was used for the study. The mycelia of the pathogen appeared as white and fluffy with a characteristic pale pink to purplish pigmentation. Microconidia were ovoid or elliptical with 0 - 1 septa, while macroconidia were fusiform with 3 – 4 septa. Chlamydospores were globose with a diameter of 6 -10 μm. The pathogen was mass multiplied in sorghum-sand medium (SSM) (2:1:1 ratio) and complete colonization of the fungus was recorded at 5 days after inoculation (DAI). Koch’s postulates were proved in 15-days-old yard long bean seedlings (var. Githika). The disease symptoms initiated as yellowing of older leaves at 7 days after transplanting, which further progressed as defoliation, withering, wilting and seedling death. In vitro studies on the evaluation of antifungal potential of bioagents, botanicals and biofumigants revealed that garlic bulbs (2 g plate-1) completely (100%) inhibited the pathogen. Rhizobium sp. (KAU) inhibited the mycelial growth by 67.77 per cent and tested positive for siderophore production, indicated by a colour change of Chrome Azurol S (CAS) agar from blue to orange. In vivo seed treatment studies revealed that sowing of seeds in soil applied with AMF @ 5 g seed-1 followed by transplanting was the promising treatment (no incidence of disease) for the management of Fusarium wilt, along with enhanced seed germination (100%), leaf number (11.00), leaf area (24.17 cm2), shoot length (16.17 cm), root length (19.83 cm) and root-shoot ratio (5.33) of the seedling. Seed treatment with Rhizobium sp. followed by transplanting was the next promising treatment with the highest leaf area (27 cm2). Scanning electron microscopy revealed intact cell structure and absence of clogging 128 in vascular tissues of the above plants where as the pathogen inoculated control recorded its hypha emerging out of xylem vessels, which were damaged and extensively clogged. A pot culture study was undertaken in yard long bean var. Githika to develop an integrated package for management of vascular wilt disease. The treatment viz., soil testbased lime application at 2 weeks before planting + soil application of Trichoderma sp. enriched in cow dung – neem cake mixture (9:1) @ 1 kg pot-1 at one week before sowing (WBS) + soil application of AMF @ 5 g seed⁻¹ at sowing followed by transplanting + soil application of PGPR mix II @ 20 g L-1 at 20, 40 and 60 DAS (T6), recorded the least disease incidence (55.50%) and disease severity (19.44%), with the highest yield (945 g plant-1with 54 pods), among the treatments. The highest AMF root colonization (49%) and number of nodules (47.00) were also recorded in this treatment. Significant reduction in the population of the pathogen in soil/ pot was also recorded in this treatment at 30 and 60 DAS. The next promising treatment was same as the best one, with soil application of PGPR mix II @ 20 g L-1 replaced by Trichoderma sp. enriched in cow dung – neem cake mixture (9:1) @ 1 kg pot-1 at 20, 40, and 60 DAS (T3) which recorded reduced disease incidence (66.66%) and severity (31.76%) with higher yield (908.33 g plant-1from 50.00 pods), AMF root colonization (45.00%) and nodules (40.67). Peak activity of peroxidase (12.07 μg g-1 min-1), polyphenol oxidase (1.587 μg g-1 min-1), and phenylalanine ammonia lyase (11.703 μg g-1 min-1) at 72 hours after inoculation was recorded in the promising treatment. Thus, the present study revealed the integrated disease management package viz., soil test-based lime application at 2 weeks before planting + soil application of Trichoderma sp. enriched in cow dung – neem cake mixture (9:1) @ 1 kg pot-1 at one WBS + soil application of AMF @ 5 g seed⁻¹ at sowing followed by transplanting + soil application of PGPR mix II @ 20 g L-1 at 20, 40 and 60 DAS can effectively manage vascular wilt of yard long bean incited by F. oxysporum in homesteads. Furthermore, the study confirms a beneficial quadripartite association among AMF, Trichoderma sp. and the plant growth promoting rhizobacteria in yard long bean plants, as observed from the effective management of the disease and enhanced plant growth and yield attributes even in the presence of the soil borne pathogen.
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    Risk assessment and habitat invasibility of Ageratine adenophora (Spreng) R.M. King & H.Rob in Pampadum Shola National park, Kerala
    (Department of Forest Resource Management, College of Forestry, Vellanikkara, 2024-12-17) Nikhil, P V; Aneesh, K S
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    Comparative assessment of the spatial distribution and edaphic attributes of mangroves in Perumba and Puthuvype regions
    (Department of Forest Resource Management, College of Forestry, Vellanikkara, 2024-01-25) Rohan, M S.
    Mangroves are characterized by salt-tolerant vegetation thriving in tropical and subtropical coastlines. It provides critical ecological services and a source of livelihood for coastal communities. Globally, these crucial ecosystems are currently under threat due to the over-exploitation of natural resources. The mangroves in the state of Kerala have witnessed a drastic reduction in the area from seven hundred sq. km to a mere nine sq. km over the last five decades. Developmental activities and anthropogenic disturbances in the coastal areas are the major threats to these sensitive ecosystems. The knowledge of the extent of disturbance, the changes brought by the anthropogenic activities and their effect on the mangrove vegetation are the prerequisites for the sustainable management of these ecosystems. In this context, the present research work studied the extent of change in mangrove areas, variation in vegetation structures, soil and water properties among two contrasting regions namely, the Perumba river region with low and the Puthuvype region with high human disturbances. The Land Use Land Cover (LULC) classification for the current year has shown almost same percentage of mangroves to the total area in both the studied regions. In the present study, we used the three most widely used machine learning algorithms for the classification process. Among the machine learning algorithms studied, the Gradient Tree Boost (GTB) algorithm with a combination of Sentinel 1, 2 datasets and few spectral indices shown exemplary performance (88 % accuracy) in classifying mangrove areas. Change detection analysis showed a positive trend in mangrove cover in Perumba region (7.03 % increase) and contrarily a negative trend (66.51 % decrease) in the Puthuvype region during the study period (2013 - 2023). Phytosociological analysis figured out seven species belonging to four families in both Perumba and Puthuvype regions. The only difference in the species composition between the two regions is that Kandelia candel was found only in Perumba region, while it was replaced by Bruguiera gymnorhiza in the Puthuvype region. The common species present among these two regions were Avicennia officinalis, Bruguiera cylindrical, Excocaria agallocha, Rhizophora apiculate and Rhizophora mucronata. The Perumba region exhibits higher vegetation diversity indices when compared to the Puthuvype region. Perumba region exhibited higher seedling, tree, and sapling density, indicating a healthier mangrove ecosystem. In both regions, the majority of trees belong to the girth xii class of 20-30 cm. Further, Important Value Index (IVI) identified Avicennia officinalis as a dominant species followed by Rhizhophora mucronata in both the regions. Soil analysis showed a significant variation for chemical properties between the regions studied. Electrical conductivity, soil organic carbon, available nitrogen, available potassium, sodium, magnesium, lead, and chromium levels were recorded higher values in the Perumba region. Meanwhile, available phosphorus content was found higher in the Puthuvype region. In addition, biological properties viz, actinomycetes, bacteria, and fungi populations were higher in the Perumba region. Moreover, water analyses also revealed a maximum electrical conductivity, salinity and turbidity in the Perumba region. Altogether, the study showed a declining mangrove population in the Puthuvype region due to significant changes in the mangrove ecosystem brought by the intense anthropogenic interventions in the mangrove ecosystem, necessitating immediate action for the restoration of this fragile ecosystem.
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    Characterization,Documentation and Management of fungal diseases of selected forest nursery seedlings of Kerala
    (Department of Forest Resource Management,College of Forestry, Vellanikkara, 2024-06-04) Kiran Mohan; Gopakumar, S
    Disease free planting stock significantly ensures better field survival, thereby reducing the burden of economic loss and meeting the targets of climate change mitigation. Teak (Tectona grandis L.f.), Indian beech (Pongamia pinnata (L.) Pierree), custard apple (Annona squamosa L.), guava (Psidium guajava L.), and Indian laburnum (Cassia fistula L.), which are extensively used for afforestation programs in Kerala, are severely affected by fungal pathogens at the nursery stage. Hence, an investigation was undertaken to identify the major fungal diseases associated with the above mentioned seedlings in Kerala and to assess the efficacy of selected fungicides and bio-control agents through in vitro and in vivo studies. A purposive sampling survey was conducted in 40 forest nurseries across the state during summer (Feb-May), monsoon (June-Sept), and post-monsoon (Oct-Jan) seasons in 2021 to monitor the occurrence of fungal diseases and collect diseased samples. Out of the seven major fungal diseases, three from teak, and one each from the other four tree crops were observed respectively. Major fungal diseases noticed from teak seedlings include teak leaf rust (TLR), teak die back (TDB), and teak leaf spot (TLS). Pongamia foliar disease (PFD) from Indian beech, annona die back (ADB) from custard apple, guava leaf spot (GLS) from guava, and cassia die back (CDB) from Indian laburnum are the other selected major diseases. Teak leaf rust (TLR) was the most common and severe foliar disease observed in teak from various nurseries across the state and irrespective of the five agro-ecological zones (AEZs), the maximum Percent Disease Index (PDI) and Percent Disease Severity (PDS) (60.0% and 52.8%, respectively) recorded from Chettikkulam (AEZ IV- High Hills) in the monsoon season. Teak die back (TDB) disease (PDI 62%) was observed only from Edayazham (AEZ I- Coastal Plain) during the pre-monsoon period. Teak leaf spot (TLS) was noticed only from Kudayathoor nursery (AEZ III- Foothills) during the pre-monsoon season. In Indian beech, PFD was observed from different nurseries irrespective of AEZs during the study period, and Chettikkulam (AEZ IV- High Hills) recorded the maximum PDI (80.0%) and PDS (63.2%) in the monsoon. The major disease of custard apple seedlings, i.e., ADB, was observed from different nurseries, and the maximum PDI (55.0%) was recorded at Kanakappalam (AEZ III- Foothills). Guava leaf spot (GLS) was noticed as the common disease in guava seedlings during the survey, and the maximum PDI (60.0%) and PDS (55.0%) were recorded at Varanadu nursery (AEZ I- Coastal Plain). In Indian laburnum, CDB was found to be a common disease throughout the state, and at the location Kattamudy (AEZ IV- High Hills), it recorded the maximum PDI (50.0%). Based on the available data during the study period, TLR showed a positive correlation with temperature and a negative correlation with rainfall. However, PFD showed a negative correlation with temperature and a positive correlation with rainfall and ADB showed a positive correlation with rainfall as well as relative humidity. In the case of GLS, no common trend was detected, and CDB showed a negative correlation with relative humidity. The typical orange colour urediniospores on the backside of the affected teak leaf characterizes TLR symptoms. Meanwhile, TLS is noticed as scattered black spots with a greyish center. Whereas TDB originates as leaf blight and subsequently spreads throughout the seedlings. Symptoms of PFD are observed as irregular chlorotic spots on the adaxial side and black dot-like sporodochia on the abaxial side. Leaf yellowing, followed by inward curling and the further spread of a necrotic area throughout the seedling, is the typical symptom of ADB. Meanwhile, GLS is noticed as grey to cream-colored blighted region surrounded by black, brown, or violet round margin. In the case of CDB, the initial symptom of leaf blight later spreads throughout the seedling. The pathogenicity of the major foliar diseases (TLR, TLS, PFD, GLS) was proven using Mycelial Bit Inoculation Method (MBIM), Micro Droplet Inoculation Technique (MDIT), and inoculation with the infected leaf method. Spore suspension method and mass multiplied pathogen in the substrate method were adopted for major root diseases (TDB, ADB, CDB). The obligate parasite (TLR) was identified as Olivea tectonae based on the morphological characters of urediniospores and all other major pathogens were identified upto the species level based on cultural as well as morphological characters, coupled with characters of amplified gene regions (ITS region and LSU region). The TDB pathogen was thus identified as Colletotrichum fruticola, TLS pathogen as Corynespora cassiicola, PFD pathogen as Cladosporium tenuissimum, ADB pathogen as Colletotrichum siamense, GLS pathogen as Colletotrichum siamense, and CDB pathogen as Alternaria alternata. In vitro evaluation studies revealed that carbendazim 12% + mancozeb 63%, mancozeb, and propineb stood out against major foliar diseases. However, in vivo experiment results showed that carbendazim 12% + mancozeb 63%, mancozeb, hexaconazole, and Trichoderma asperellum were observed to be efficient against major foliar diseases. Similarly, carbendazim 12% + mancozeb 63%, mancozeb, Bordeaux mixture, and hexaconazole showed promising results against major root diseases during in vitro as well as in vivo experiments.
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    Ecotourism carrying capacity of Nelliampathy, Palakkad, Kerala
    (Department of Forest Resource Management, College of Forestry, Vellanikkara, 2024-02-26) Rathna, V.; Gopakumar, S
    Ecotourism is globally embraced as a niche segment of sustainable tourism, transforming conventional mass tourism and increasingly being recognized as a strategy for sustainable forest management in natural areas. However, to address the potential threats arising from an excessive influx of visitors and inadequate regulations in these areas, it is imperative that effective ecotourism planning and management must establish and uphold optimal thresholds, commonly denoted as the “carrying capacity of destinations”. Despite its importance in managing visitor numbers, many key ecotourism destinations currently do not adhere to this concept. This study focused on assessing the ecotourism carrying capacity (ETCC) for one of the major hill-based ecotourism attractions in Kerala, ‘Nelliampathy’, which faces immense pressure from tourists, by taking into account various site-specific physical, biological or ecological and social factors. Tourist's perceptions were also obtained through a survey conducted with 91 respondents with a pre-tested questionnaire, scheduled every fortnight from June to September. Furthermore, a brief study on the valuation of the use (recreational) and non-use values of Nelliampathy was carried out. The study established Effective Carrying Capacity (ECC) estimates for various destinations: Government Orange Farm, Kesavanpara, Seetharkundu, Pakuthippalam KFDC, Minnampara and Karappara Bridge at 587, 302, 153, 110, 40 (approximately 5 trips per day) and 8 visitors per day, respectively. The occupancy rate of destinations revealed that Karappara far exceeded the carrying capacity, followed by Minnampara and Seetharkundu. While the current visitation rates are actually below these estimates for some destinations like Kesavanpara and Govt. Orange Farm, there is a risk of congestion and overcrowding, particularly during peak seasons and holidays. ETCC assessment underscores the importance of improving the management capacity in terms of personnel, infrastructure and equipment and judicious monitoring of limiting factors that could reasonably increase the carrying capacity of these sites. Extended projection periods, especially for KFDC and Govt. Orange Farm could be strategically utilized to alleviate tourist pressure. The tourist profile indicated a significant majority from Kerala (92.31%), mainly comprising students (25.27%) and middle-aged individuals (46.15%) with a literate background (41.76%), favouring exclusive weekend day trips to Nelliampathy (79%). Overall, tourists held a positive perception about natural attractions and environmental characteristics of Nelliampathy, though a neutral stance was observed regarding travel-related concerns and other tourist assistance services. Despite its aesthetic beauty, Nelliampathy received negative feedback due to limited accessibility to emergency services. Tourists typically used personal cars (47%) and often engaged in group tourism with friends and family. Substitute destinations suggested include Munnar, Wayanad, Parambikulam Reserve and Silent Valley Park. The anticipated increase in tourist flows in Nelliampathy necessitates a re-evaluation of destination ticketing systems. Visitor willingness to pay (WTP) reflected environmental awareness, providing an opportunity for engaging tourists in destination improvement initiatives. This comprehensive understanding aids in shaping the future ecotourism management plan for Nelliampathy and the study offers a potential model for assessing carrying capacity at other ecotourism sites in the state