Selenium - An environmentally friendly micronutrient in agroecosystem in the modern era: An overview of 50-year findings.

Agricultural productivity is constantly being forced to maintain yield stability to feed the enormously growing world population. However, shrinking arable and nutrient-deprived soil and abiotic and biotic stressor (s) in different magnitudes put additional challenges to achieving global food security. Though well-defined, the concept of macro, micronutrients, and beneficial elements is from a plant nutritional perspective. Among various micronutrients, selenium (Se) is essential in small amounts for the life cycle of organisms, including crops. Selenium has the potential to improve soil health, leading to the improvement of productivity and crop quality. However, Se possesses an immense encouraging phenomenon when supplied within the threshold limit, also having wide variations. The supplementation of Se has exhibited promising outcomes in lessening biotic and abiotic stress in various crops. Besides, bulk form, nano-Se, and biogenic-Se also revealed some merits and limitations. Literature suggests that the possibilities of biogenic-Se in stress alleviation and fortifying foods are encouraging. In this article, apart from adopting a combination of a conventional extensive review of the literature and bibliometric analysis, the authors have assessed the journey of Se in the "soil to spoon" perspective in a diverse agroecosystem to highlight the research gap area. There is no doubt that the time has come to seriously consider the tag of beneficial elements associated with Se, especially in the drastic global climate change era.

Seed priming with Se alleviate As induced phytotoxicity during germination and seedling growth by restricting As translocation in rice (Oryza sativa L c.v. IET-4094).

Interactive aspect of among selenium (Se) and As (As) to mitigate As induced phytotoxicity in rice during germination and seedling growth has been based on mostly to petriplates and hydroponic mode of experiments. In this investigation we explore the consequences of sowing Se primed rice seeds in As spiked soil. Unprimed, hydroprimed and Se primed rice (IET-4094) seeds sown in As spiked soil, with five replications, arranged in complete randomized design for evaluating the impacts of seed priming on germination and seedling growth as well as As uptake and translocation pattern. Se promotes germination, seedling growth by modulating proline content, lipid peroxidation in root and shoot beside enhancing total chlorophyll content significantly in both As free and As spiked soil as compared to their respective unprimed and hydroprimed counterparts grown alike. Findings also indicates that seed priming with Se was able to execute dual roles i.e. a promotive and antagonistic aspect against As by restricting maximum soil As load to the root (with greater bioconcentration factor) and reducing translocation of As from root to shoot in a more practical and farmer friendly way to mitigate As induced toxicity and enhance germination and growth in rice seedlings.

Effect of Gamma Radiation on Zinc Tolerance Efficiency of Aspergillus terreus Thorn.

The present study emphasizes the potential of gamma radiation in enhancing zinc tolerance of Aspergillus terreus. Gamma-exposed A. terreus could tolerate 1.13 times more Zn, reflecting higher growth (in terms of CFU) under Zn stress and enhanced Zn removal efficacies than their unirradiated counterparts. Radiation-induced upregulation of antioxidative system (SOD, CAT, GSH and MT) of A. terreus is responsible for radiation-induced enhancement of Zn tolerance. FTIR spectra reveals the involvement of functional groups in Zn biosorption; SEM study divulges the structural changes due to metal and gamma exposure and SEM-EDX depicts the Zn uptake by A. terreus (both in gamma-exposed and unexposed conditions). This work sheds light toward utilizing low doses of ionizing radiation for making more metal-tolerant fungi and the possible mechanisms adopted by A. terreus for being more metallo-resistant.

WITHDRAWN: Deposition and uptake of metals in urban canopy: Atmospheric arsenic sequestration.

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Heavy metal accumulation in vegetables grown in a long-term wastewater-irrigated agricultural land of tropical India.

In the present study, the magnitude of contamination of vegetables with heavy metals (Pb, Zn, Cd, Cr, Cu and Zn) was determined in a long-term wastewater-irrigated agricultural land. Heavy metal concentrations in vegetables were several folds higher in wastewater-irrigated site compared to clean water-irrigated area. The wastewater-irrigated crops analysed in this study are heavily contaminated with heavy metals. Concentrations of Pb, Zn, Cd and Cr in all the sewage-fed vegetables were beyond the safe limit of FAO/WHO and Indian standard. Contamination is at its highest level in radish and spinach. Daily intake values of Pb, Cd and Ni through consumption of sewage-fed vegetables exceeded the recommended oral dose of metal for both adult and children. The study concludes that wastewater irrigation led to accumulation of heavy metals in vegetables causing potential health risk to consumers.

SEMEDS: an important tool for air pollution bio-monitoring.

Plant canopies act as absorbers of air-borne dust particles. Characterization of the dusts present over the leaf surfaces can indicate the nature of contaminant present in the surrounding area and possible sources as well. Dust particulates get adsorbed on both the surfaces of leaves, however more dust particulates get deposited on the upper surface. These dusts contain many inorganic elements, which were analyzed in the present study. For the present investigation, SEMEDS technique used to characterize the dusts adsorbed over the leaf surfaces. Using SEMEDS the samples were analyzed by two types of methods i.e. point analysis and elemental mapping. Both the methods showed the presence of elements like Si, Al, Fe, Mg, and Ca in the dusts adsorbed over the leaf surfaces. Thus, SEMEDS can be used for in situ air pollution monitoring using tree leaves from the area concerned.

Relationship between CH4 and N2O flux from soil and their ambient mixing ratio in a riparian rice-based agroecosystem of tropical region.

Temporal variations of the ambient mixing ratio of greenhouse gas (CH(4) and N(2)O) in a riparian rice-based agro-ecosystem of tropical region were studied during 2005-2006 in coastal Odisha. The endeavour was made with the hypothesis that the ambient mixing ratio of CH(4) and N(2)O depends on the changes in the flux of CH(4) and N(2)O from the rice fields in the riparian rice ecosystems. A higher ambient mixing ratio of CH(4) was recorded during the tillering to grain filling stages of the rice crop, during both dry and wet seasons. The higher ambient mixing ratio of CH(4) during the wet season may attribute to the higher CH(4) emission from the rice field. The average mixing ratio of CH(4) was recorded as 1.84 ± 0.05 ppmv and 1.85 ± 0.06 ppmv during 2005 and 2006, respectively. The ambient CH(4) mixing ratio was recorded negatively correlated with the average ambient temperature. The N(2)O mixing ratio ranged from 261.57 to 399.44 ppbv with an average of 330.57 ppbv during 2005. However, the average mixing ratio of N(2)O was recorded as 318.83 ± 20.00 ppbv during 2006. The N(2)O mixing ratio was recorded to be negatively correlated with rainfall and average ambient temperature. Significant negative correlation (r = -0.209) of N(2)O with sunshine hours may attribute to the photochemical break down of N(2)O. The temporal variation of N(2)O flux from the rice field does not affect the ambient mixing ratio of N(2)O in the same way as in the case of the ambient mixing ratio of CH(4). However, the higher mixing ratio of N(2)O during the fallow period of the post monsoon period may attribute to the N(2)O flux from soil. Results indicate that intensively cultivated coastal ecosystems can be a major source of ambient greenhouse gas.

Occurrence of arsenicosis in a rural village of Cambodia.

Ninety-seven subjects belonging to 40 families in a village in Cambodia were examined in a health camp where all the cases with skin disease assembled. These people had evidences of chronic arsenic exposure from reports of testing of water samples and of hair and/or nail studied. Seventy cases were diagnosed to be suffering from arsenicosis (Clinically and laboratory confirmed according to WHO criteria) as all these cases had evidences of pigmentation and/or keratosis characteristic of arsenicosis and history of exposure of arsenic contaminated water and/or elevated level of arsenic in hair and/or in nail. Highest number of cases belonged to age group of 31 to 45 yrs, both the sexes are more or less affected equally. Evidence of both pigmentation and keratosis were found in 60 cases (85.7%) while only pigmentation and only keratosis was found in 6 (8.5%) and 4 (5.7%) cases respectively. It was interesting to find 37.04% of children below the age of 16 years had skin lesions of arsenicosis. The youngest child having definite evidence of keratosis and pigmentation was aged 8 years, though two children aged 4 and 5 yrs had feature of redness and mild thickening of the palms. The minimum and maximum arsenic values detected in the nails were 1.06 and 69.48 mg/Kg respectively and the minimum and maximum arsenic values in hair were 0.92 and 25.6 mg/Kg respectively. No correlation was observed between arsenic concentration in drinking water and arsenic level in nail and hair. This is the first report of clinical and laboratory confirmed cases of arsenicosis in Cambodia.

An assessment of heavy metal contamination in vegetables grown in wastewater-irrigated areas of Titagarh, West Bengal, India.

The effects of municipal wastewater irrigation on the accumulation of heavy metals (Pb, Zn, Cd, Cr, Cu and Ni) in soil and vegetables were investigated by monitoring wastewater-irrigated agricultural field of Titagarh, 24-Parganas (North), West Bengal, India. The mean concentrations of Pb, Ni, Cu in the irrigation water and the mean Cd content in soil were much above the recommended level. The concentrations of Pb, Zn, Cd, Cr and Ni in all the examined vegetables were beyond the safe limits. The study reveals that heavy metal-contaminated vegetables grown in wastewater-irrigated areas may pose public health hazards.

Isolation and characterization of high quality DNA from marine benthic macroalgae.

The isolation of high quality DNA is essential for many molecular biology applications including polymerase chain reaction (PCR) and endonuclease restriction digestion based techniques. An easy and inexpensive protocol has been developed for extracting genomic DNA from seven species of algae viz. Lola capillaries, Enteromorpha intestinalis, Ulva lactuca and Rhizoclonium sp belonging to Chlorophyceae, Catenella nipae, Polysiphonia mollis belonging to Rhodophyceae and Dictyota ceylanica belonging to Phaeophyceae group were collected from the coastal regions of Sunderban delta in West Bengal, India dominantly growing on mud flats, bark of different mangrove trees, pneumatophores, stilt roots, concrete surfaces, wooden and bamboo poles, sides of the boats and other water vehicles inundated during high tides. The DNA was found suitable for restriction endonuclease digestion and PCR amplification with randomely amplified polymorphic DNA (RAPD) primers. The A260/A280 ratio of 1.15 0.14 to 1.94 indicated little contamination from proteins and polysaccharides. The PCR amplification with RAPD primers showed its suitability in PCR based techniques and the restriction digestion with Eco RV confirmed its suitability for hybridization based techniques. The protocol is equally good for isolating DNA from both fresh as well as preserved materials.

Biological process of arsenic removal using selected microalgae.

In the present investigation, growth of the organisms was reduced due to presence of arsenic (III) and (V) in the culture medium. In comparison to arsenic (V), arsenic (III) had more toxic effect on microalgae. Among the different algal strains, blue green algal species Oscillatoria-Lyngbya mixed culture showed maximum efficiency in removing arsenic (64%) after 21 days of incubation and the same algal species could remove arsenic (III), but 60% after 21 days when incubated in 0.1 mg/l arsenic (III) containing medium. Maximum removal was observed at their exponential growth phase and also so sometime extended to the stationary phase.

Air quality of Kalyani township (Nadia, West Bengal) and its impact on surrounding vegetation.

Plant can act as an indicator of environmental pollution by changing its anatomical, biochemical and physiological features. This has been well recognized in the past. In Kalyani township a case of study was undertaken to determine the extent of air pollution and its impact on some dominant local flora by studying their anatomico-biochemical features of leaves in a comparative manner. The total chlorophyll content, epidermal thickness, stomatal length and breadth of the leaves were found to decrease while the leaf thickness, stomatal frequency were found to increase in case of pollution stress plants with respect to control plant population of non polluted habitat. This indicate that the pollutants have imparted direct adverse effect on biochemical and anatomical make-up of the population stressed plant.

Road traffic noise in Calcutta metropolis, India.

A comprehensive study on traffic noise level at twenty four pre-selected road transaction of Calcutta Metropolis was carried out during 1993-94. Noise levels were measured at each of twenty four sites, based on predetermined sampling interval and altogether 2880 observations were generated by recording data continuously for 24 hours. The Lcq 24, exceedence levels, LD, LN, LDN, LNP and TNI were determined. Traffic flow density as measured along with noise data recording were then compared for establishing relationship with noise level. Finally the clustering of the sites were made based on variable viz. Lcq 24 and traffic follow density.