• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.238-244
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• 2010

Rhizobia are well-known for their ability to infect and nodulate legume roots, forming a nitrogen-fixing symbiosis of agricultural importance. In addition, recent studies have shown that rhizobia can colonize roots and aerial plant tissues of rice as a model plant of the Graminaceae family. Here we show that rhizobia can invade tobacco, a model plant belonging to the Solanaceae family. Inoculation of seedling. roots with five GFP-tagged rhizobial species followed by microscopy and viable plating analyses indicated their colonization of the surface and interior of the whole vegetative plant. Blockage of ascending epiphytic migration by coating the hypocotyls with Vaseline showed that the endophytic rhizobia can exit the leaf interior through stomata and colonize the external phyllosphere habitat. These studies indicate rhizobia can colonize both below- and above-ground tissues of tobacco using a dynamic invasion process that involves both epiphytic and endophytic lifestyles.

• Journal of Forest and Environmental Science
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• v.36 no.1
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• pp.37-46
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• 2020

Vegetation carbon sequestration and regeneration are the two major parameters of forest research. In this study, we analyzed the vegetation carbon stock and regeneration of community-managed pine plantation of Kathmandu, central Nepal. Vegetation data were collected from 40 circular plots of 10 m radius (for the tree) and 1m radius (for seedling) applying a stratified random sampling and nested quadrat method. The carbon stock was estimated by Chave allometric model and estimated carbon stock was converted into CO₂ equivalents. Density-diameter (d-d) curve was also prepared to check the regeneration status and stability of the plantation. A d-d curve indicates the good regeneration status of the forest with a stable population in each size class. Diversity of trees was very low, only two tree species Pinus roxburghii and Eucalyptus citriodora occurred in the sample plots. Pine was the dominant tree in terms of density, basal area, biomass, carbon stock and CO₂ stock than the eucalyptus. The basal area, carbon stock and CO₂ stock of forest was 33±1.0 ㎡ ha^-1, 108±5.0 Mg ha^-1 and 394±18 Mg ha^-1, respectively. Seedling and tree density of the plantation was 4,965 ha^-1 and 339 ha^-1 respectively. The forest carbon stock showed a positive relationship with biomass, tree diameter, height and basal area but no relationship with tree density. Canopy cover and tree diameter have a negative effect on seedling density and regeneration. In conclusion, the community forest has a stable population in each size class, sequestering a significant amount of carbon and CO₂ emitted from densely populated Kathmandu metro city as the forest biomass hence have a potentiality to mitigate the global climate change.

• Journal of Ecology and Environment
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• v.44 no.4
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• pp.222-228
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• 2020

Background: Parthenium hysterophorus is a noxious invasive weed in tropical and subtropical regions of the world, including Nepal. Among 11 species of biological control agents released to control P. hysterophorus in Ausrtalia, winter rust Puccina abrupta var. partheniicola arrived fortuitously and has established in Kathmandu Valley, Nepal, nearly a decade back. However, the prevalence and effectiveness of this rust as a biological control agent in Kathmandu remain unknown. To address this knowledge gap, a roadside survey was done at an interval of 2 ± 0.25 km in Kathmandu Valley to assess the P. abrupta var. partheniicola incidence and its impacts on P. hysterophorus. Infested individuals of P. hysterophorus were further divided into four severity classes (very low, low, medium, and high), and rust incidence was calculated. The impact of the winter rust on the growth of P. hysterophorus was assessed by comparing biomass and seed output of infested and non-infested individuals. Results: Among 81 locations where P. hysterophorus was present in the Kathmandu Valley, winter rust infestation was observed at 98% locations. At some locations within Kathmandu Valley such as Tinkune, Kirtipur, Chabahil, Buddha Chowk, and Dhobighat, the impacts of the rust on P. hysterophorus were medium to high. Aboveground biomass and seed output of P. hysterophorus were reduced by 47% and 73%, respectively, due to winter rust infestation. The study indicates that winter rust incidence is widespread in Kathmandu Valley with very low to high levels of damages to P. hysterophorus depending on the localities. Conclusion: The rust has, therefore, a potential to reduce the growth performance of P. hysterophorus, and it can be used as a component of integrated management of P. hysterophorus by introducing to other suitable areas in Nepal.

• Journal of Ecology and Environment
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• v.47 no.3
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• pp.146-156
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• 2023

Background: Endemic species are important components in the flora of most world regions. Most of these species have become threatened and exposed to extinction within the last few years. The present study aims to evaluate the ecosystem services offered by the endemic plant taxa in Egypt and the threats that affect them. Twenty-five field visits were conducted during summer 2018 to spring 2022 to several locations all over Egypt. In each location, the main habitats, national distribution, abundance, goods and threats were recorded. Results: Egypt has 41 endemic taxa belonging to 36 genera and 20 families inhabiting 10 main habitats. Rocky surfaces and sandy formations have the highest number of endemic species. The relation between the number of endemic taxa and the abundance categories indicated that 2 taxa are rare (4.9% of the total taxa), while the remaining were very rare (95%). The most represented offered good was the medicinal uses (32 taxa = 78%), while fuel plants were only represented by 2 taxa (2 taxa = 4.9%). Besides, 14 taxa (34.1% of the total studied taxa) have at least 1 environmental service. Soil fertility (7 taxa = 50%) was the most represented, followed by sand accumulations (6 taxa out of 14 taxa = 43%), while shading plant was the least (1 taxon = 7.1%) (Rosa arabica). The most represented threat is over-cutting and over-collecting (38 taxa = 92.7%), while mining and quarrying is the least represented (4 taxa = 9.8%). Conclusions: The potential and actual goods, services and threats of the endemic taxa were assessed as follows; field observation, information collected from local inhabitants and herbalists, and a literature review. The present study recommended planning a strategy about the importance, threats and conservation of endemic taxa in Egypt that would help in the protection and rescue of these plants and increase awareness about the importance of these plants.

• Mycobiology
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• v.33 no.1
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• pp.19-22
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• 2005

We investigated the effect of nitrogen fixing Azotobacter bioinoculant on the mycelial growth and the rate of substrate utilization by Pleurotus eous. The synergistic or antagonistic role of the microorganism during dual culturing with the mushroom or the competitor molds Trichoderma viride, and Trichoderma reesi was studied. Azotobacter was inhibitory to the molds, which are competitive to the mushroom in the seed spawn substrate, but was synergistic towards the mushroom. The growth, substrate utilization potential as total nitrogen content and cellulase enzyme activities of the mushroom in the seed spawn substrate were also enhanced in the presence of the bioinoculant at lower inoculum concentrations, upto 5 ml broth culture per spawn bottle.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.2098-2100
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• 2009

A new tetrahydroanthracene, 3,6,9-trihydroxy-3,4-dihydroanthracen-1(2H)-one (1), six phenolics, moscatilin (2), gigantol (3), batatasin (4), moscatin (5), 9,10-dihydromoscatin (6), 10-dihydrophenanthrene-2,4,7-triol (7), and a sesquiterpenoid, corchoionoside C (8), together with two sterols $\beta$-sitosterol (9) and daucosterol (10), were isolated from the stems of Dendrobium polyanthum. Compounds 1 and 2 were assessed for cytotoxic activity against two human tumor cell lines (A549 and HL-60).

• The Korean Journal of Ecology
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• v.22 no.2
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• pp.85-88
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• 1999

Aqueous and dichloromethane (DCM) extracts of leaves, root bark and inflorescences of Parthenium hysterophorus L. at various concentrations were used to quantify its allelopathic potential against Indigofera tinctoria, Amaranthus viridis, A. gangeticus, Phaseolus mungo (cv. CO 1), Sorghum vulgare (cv. SPT- 462). Pennisetum typhoideus (cv. WCC-75) and Eleusine corocana (cv. CO 1). The aqueous extracts were more inhibitory than the DCM extracts to the germination and seedling growth of the plants studied. The relative rate of inhibition increased in the order of inflorescences. leaves and root bark in the aqueous extracts. whereas DCM root bark and inflorescences extracts were promoted at lower concentrations.

• The Korean Journal of Ecology
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• v.26 no.5
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• pp.251-254
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• 2003

To control the spread of surface fire in the rangelands and to check the entry of fire into forest systems from grassland patches, 26 evergreen / succulent species were selected and among them 3 shrubby species such as Berberis tintoria Lesch, Elaeagnus kologa Schlecht and Rhodomyrtus tomentosa Wt. were screened for vegetational fire breaks on the basis of leaf moisture content and some other ecological characters. The fire trail experiments indicate that crossing of fire was checked by the fire belt size of 5 ${\times}$ 1.5m for all the three species. However, due to higher fire retardant capacity, the Ire belt of R. tomentosa was effective in comparison to other two species.

• ALGAE
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• v.25 no.3
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• pp.115-120
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• 2010

The natural growth of a population of Gomphosphaeria aponina Kutzing (Chroococcales, Cyanoprocaryota) was studied in a cemented freshwater tank in Allahabad, India. This population appeared to be a polymorphic species. Different species of the genus Gomphosphaeria have been segregated based on morphological features of colonies, cells and mucilage. However, these features are not well defined for different species. Our observations revealed many feature variations and, interestingly, certain features that have been described for different Gomphosphaeria species were seen in a single population. In this study, records of such variable morphological features were possible due to the availability of numerous specimens and continuous observations for more than two years. Further, this study revealed two points: (i) more detailed morphological studies are required both from nature as well as in culture to identify critical differences among the species, and (ii) molecular characterization of taxa appears to be necessary for final species settlement.

• ALGAE
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• v.23 no.1
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• pp.71-74
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• 2008

Catenella impudica (Mont.) J.Ag is an important species for human consumption from estuarine regions of Asia. Seasonal shedding of carpospores and tetraspores was quantified between January and December 2004 for natural populations of C. impudica. Vegetative and tetrasporophytic plants were available throughout the year but gametophytic plants were observed only from September to May. Tetraspore shedding was observed throughout the year and carpospores shedding was noticed only during the months when material was available. Hydrographical conditions of the estuary such as low water temperature and low salinity are correlated to the formation and release of carpospores and tetraspores in C.impudica