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Aim: Potassium (K) is one of the three major nutrients required of plant growth and muriate of potash (MoP) is the only recognized chemical fertilizer used in agriculture. In many countries, 100% of the applied MoP is imported costing huge revenue. Application of suitable potassium-solubilizing bacteria (KSB) as biofertilizer could be an integral part of K management in arable soil. The object of this study was to evaluate K-solubilizing ability of a ubiquitous micro-organism as KSB to supplement K in soil. Methods and Results: Strain (O-5) was isolated from tea-growing soil and identified as Bacillus pseudomycoides. Phylogenetic analysis revealed that the nearest neighbours of B. pseudomycoides strain O-5 were Bacillus cereus, Bacillus thuringiensis and Bacillus toyonensis. Though the species was first identified in 1998 and is ubiquitous in soil, the role of this group of micro-organisms in nutrient cycling in soil has not been studied before. Strain solubilized 33Á32 AE 2Á40 lg K ml À1 in mica waste (MW; muscovite type mineral)-amended broth after 7 days incubation at 30 AE 1°C. In a soil microcosm study under laboratory condition, B. pseudomycoides strain O-5 increased K availability by 47Á0 AE 7Á1 mg kg À1 after 105 days incubation, while the strain released 104Á9 AE 15Á3 mg K kg À1 in MW-treated soil. In this study, application of isolated B. pseudomycoides with MW significantly increased K availability in soil, and that in turn facilitated K uptake by tea plants. Conclusion: Based on the data, it could be inferred that B. pseudomycoides could mobilize K from bound form in soil and can be utilized as K-solubilizing biofertilizer especially in combination with MW for supplementing K in soil. Significance and Impact of the Study: Bacillus pseudomycoides strain O-5 has potential to be used as K-solubilizing biofertilizer in agriculture.

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The successful establishment of an invasive plant in a novel environment has been attributed to the phenotypic plasticity of plant traits, with most studies focussing on vegetative trait plasticity in either experimental and/or natural habitat conditions. This study explores the role of phenotypic plasticity, in both vegetative and reproductive traits, of an invasive plant Mikania micrantha growing as a ground cover in diverse urban areas in the city of Kolkata, India. Quadrat based plant and soil sampling was conducted in three habitat types, namely roadsides, natural areas and abandoned plots, from four regions within the city. The above ground biomass and fitness related vegetative and seed traits were estimated from the plant samples whereas soil macro-and micro-nutrients as well as soil health (in terms of organic carbon and microbial biomass carbon) were estimated from the soil samples. Habitat-specific selection of traits in M. micrantha was observed in this study. In roadside population which has more chances of long distance dispersal, the excessive production of reproductive biomass as a compensatory response to the low germination ability of the seeds was evident. In natural areas which are more prone to anthropogenic disturbance and where the plant has greater chances of local spread, modulation of both vegetative (higher SLA) and reproductive traits (lighter seeds with faster germination ability) helped the plant to maintain its population. In abandoned plots where there was more number of associated species, the longer span of germination and increased population height ensured the survivability of M. micrantha in the community. Thus, a continuous monitoring program to check for M. micrantha growth should be prioritized in urban areas due to its immense trait plasticity in different habitat conditions where uncontrolled growth can lead to its establishment and spread, thereby making its control more difficult.