Drought stress induced changes in lipid peroxidation and antioxidant system in genus Avena

Seven species of genus Avena viz., Avena sativa, Avena strigosa, Avena brevis, Avena vaviloviana, Avena abyssinica, Avena marocana and Avena sterilis were used to study the impact of drought stress on lipid peroxidation and other antioxidant enzymes. Maximum increase in the catalase activity was recorded in A. vaviloviana (129.97%) followed by A. sativa (122.82%) and A. brevis (83.38%) at vegetative stage; however at flowering stage the maximum increase was reported in A. sativa (25.62%) followed by A. sterilis (20.46%) and A. brevis (18.53%). At vegetative stage drought, maximum increase in peroxidase activity was recorded in A. sativa (122.82%) followed by A. brevis (83.38%) and A. sterilis (49.78%). Flowering stage drought, showed maximum increase in A. Sativa (27.09%) followed by A. marocana (23.50%) and A. sterilis (20.46%). A. sativa and A. sterilis showed stress tolerance at both the stages by accumulating higher percentage of peroxidase followed by A. brevis at vegetative and A. marocana at flowering stage. Level of lipid peroxidation in terms of Malondialdehyde (MDA) content was increased in the leaves when plants were subjected to moisture stress. The rate of increase in lipid peroxidation occurs irrespective of stage however; maximum increase was recorded in A. strigosa at both the stages. Avena species which showed high level of MDA content, indicates more lipid peroxidation and more membrane permeability and are comparatively more susceptible for water stress than those which produce less Malondialdehyde (MDA) content at higher magnitude of water stress such species have better capability for moisture stress tolerance.     

Assessment of soil quality under different tillage practices during wheat cultivation: soil enzymes and microbial biomass

Microbial processes, particularly enzyme activities, play crucial functional roles in soil ecology, hence serving as sensitive indicators of soil quality. We assessed the temporal dynamics of microbial biomass and selected soil enzymes (β-d-glucosidase, cellobiohydrolase, polyphenol oxidase, urease, glycine-aminopeptidase and alkaline phosphatase) during wheat cultivation, under four different tillage practices in the rice–wheat system. The four practices involved conventional tilling of soil before cultivating each crop (CTR-CTW); no tilling before cultivating rice but conventional tillage before wheat (NTR-CTW); conventional tilling before cultivating rice but no tilling before wheat (CTR-NTW) and no tilling before cultivation of each crop (NTR-NTW). Microbial biomass and activities of hydrolytic enzymes increased under NTR-NTW followed by CTR-NTW and NTR-CTW with respect to the conventional practice CTR-CTW, thus reflecting improvement in microbial activities with reduced tillage frequency. Enzyme activities generally depended on soil moisture and temperature, but nature of relationships varied among different practices. Nutrient demand appeared to be the strongest driver of alkaline phosphatase and urease, and soil temperature for glycine-aminopeptidase. Under CTR-CTW, activities of most of the extracellular enzymes were related with β-d-glucosidase or urease, but such relations altered under rest of the practices. The study showed that extracellular soil enzymes respond sensitively to tillage practices as well as environmental variables, particularly soil temperature and moisture and hence can serve as a sensitive indicator of changes in soil processes. Considering improvement in microbial biomass and enzymatic activities as indicators of better soil quality, adoption of no tillage apparently improved soil quality. Still, more number of field studies are required under tillage managements to explore the relationships between different enzyme activities and environmental factors.     

Removal of arsenic by Acidothiobacillus ferrooxidans bacteria in bench scale fixed-bed bioreactor system

In the present study arsenic contaminated simulated water and groundwater was treated by the combination of biological oxidation of tri-valent arsenite [As (III)] to penta-valent arsenate [As (V)] in presence of Acidothiobacillus ferrooxidans bacteria and its removal by adsorptive filtration in a bioreactor system. This method includes the immobilisation of A.ferrooxidans on Granulated Activated Carbon (GAC) capable of oxidising ferrous [Fe (II)] to ferric [Fe (III)]. The Fe (III) significantly converts the As (III) to As (V) and ultimately removed greater than 95% by the bed of GAC, limestone, and sand. The significant influence of Fe (II) concentration (0.1–1.5?gL^?1), flowrate (0.06–0.18?Lh^?1), and initial As (III) concentration (100–1000?µgL^?1) on the arsenic removal efficiency was investigated. The simulated water sample containing the different concentration of As (III) and other ions was used in the study. The removal of other co-existing ions present in contaminated water was also investigated in column study. The concentration of arsenic was found to be <10?µgL^?1 which is below Maximum Contaminant Level (MCL) as per WHO in treated water. The results confirmed that the present system including adsorptive-filtration was successfully used for the treatment of contaminated water containing As (III) ions.     

Effect of cement dust on the growth and yield of Brassica campestris L

Plants of Brassica campestris L. var. G-S20 were treated with cement dust, at rates of 3 (B(1)), 5 (B(2)) and 7 (B(3)) gm(-2) day(-1) for 90 days. Treated plants showed a consistent reduction in growth, photosynthetic pigments, yield and oil content over control plants. The overall phytomass of treated plants was significantly decreased, the maximum reduction being 64.8% in B(3) plants, followed by B(2) plants (55.3%) and B(1) plants (43.69%) at 60 days. The effect on oil content was also greatest in B(3) plants, where it was decreased by 6.13%.     

Land application of domestic effluent onto four soil types: plant uptake and nutrient leaching

Land application has become a widely applied method for treating wastewater. However, it is not always clear which soil-plant systems should be used, or why. The objectives of our study were to determine if four contrasting soils, from which the pasture is regularly cut and removed, varied in their ability to assimilate nutrients from secondary-treated domestic effluent under high hydraulic loadings, in comparison with unirrigated, fertilized pasture. Grassed intact soil cores (500 mm in diameter by 700 mm in depth) were irrigated (50 mm wk(-1)) with secondary-treated domestic effluent for two years. Soils included a well-drained Allophanic Soil (Typic Hapludand), a poorly drained Gley Soil (Typic Endoaquept), a well-drained Pumice Soil formed from rhyolitic tephra (Typic Udivitrand), and a well-drained Recent Soil formed in a sand dune (Typic Udipsamment). Effluent-irrigated soils received between 746 and 815 kg N ha(-1) and 283 and 331 kg P ha(-1) over two years of irrigation, and unirrigated treatments received 200 kg N ha(-1) and 100 kg P ha(-1) of dissolved inorganic fertilizer over the same period. Applying effluent significantly increased plant uptake of N and P from all soil types. For the effluent-irrigated soils plant N uptake ranged from 186 to 437 kg N ha(-1) yr(-1), while plant P uptake ranged from 40 to 88 kg P ha(-1) yr(-1) for the effluent-irrigated soils. Applying effluent significantly increased N leaching losses from Gley and Recent Soils, and after two years ranged from 17 to 184 kg N ha(-1) depending on soil type. Effluent irrigation only increased P leaching from the Gley Soil. All P leaching losses were less than 49 kg P ha(-1) after two years. The N and P leached from effluent treatments were mainly in organic form (69-87% organic N and 35-65% unreactive P). Greater N and P leaching losses from the irrigated Gley Soil were attributed to preferential flow that reduced contact between the effluent and the soil matrix. Increased N leaching from the Recent Soil was the result of increased leaching of native soil organic N due to the higher hydraulic loading from the effluent irrigation.     

Total bacterial and fungal population after chlorpyrifos and quinalphos treatments in groundnut (Arachis hypogaea L.) soil

Short-term inhibitory effect on the total bacterial population was observed after chlorpyrifos and quinalphos applications in the groundnut fields, which recovered within 60 days after seed treatment and by 45 days of soil treatment. The fungal population was significantly enhanced after chlorpyrifos treatment whereas quinalphos inhibited the fungal population during the initial days of treatment but no effect was observed after 60 days of treatment. The residues of chlorpyrifos and quinalphos in the treated soil were not persistent and their half-lives ranged from 7.0 to 9.2 days and 13.2 to 20.6 days, respectively.     

Forest biomass extraction for livestock feed and associated carbon analysis in lower Himalayas,India

Accounting the changes in the net carbon (C) sink-source balance is an important component for greenhouse gas emissions (GHG) inventories. However, carbon emission due to the vegetation biomass extraction for household purposes is generally not accounted in forest carbon budget analysis due to miniscule volume and non-availability of data. However, if vegetation remains in the forests, then vegetation biomass decomposes after natural death and decay and fixes some carbon to soil and releases some directly to the atmosphere. The study attempts to quantify the carbon removal against the biomass extraction for livestock feed by collecting primary data on feed from 316 randomly selected households engaged in livestock rearing in the lower Himalayas, Uttarakhand, India and carbon flow components due to livestock production. The analysis results that average daily forest fodder consumption was 13 kg per Adult Cattle Unit (ACU) and total of 20.31 Million tonnes (Mt) consumption of forest biomass by total livestock of Uttarakhand. This results into absolute annual carbon removal of 3.25 Mt from Uttarakhand forests against the livestock fodder. However, overall carbon flow including the enteric fermentation and manure management system of livestock estimated as per IPCC guidelines, results into emissions of 9.42 Mt CO₂ eq. Therefore, biomass extraction for household purposes should be accounted in regional carbon flow analysis and properly addressed in the GHG inventories of the forests and livestock sector. Suitable measures should be taken for emissions reduction generated due to forest based livestock production.     

Distribution of Metals in the Edible Plants Grown at Jajmau, Kanpur (India) Receiving Treated Tannery Wastewater: Relation with Physico-Chemical Properties of the Soil

The implications of metal contamination of agricultural soils due to long term irrigation with treated industrial wastewater and their subsequent accumulation in the vegetables/crops growing on such soils has been assessed in an area of industrial complex, Jajmau, Kanpur (India). Physico-chemical properties of the soil were also studied. The soil and vegetables/crops were sampled from an area of 2100 acre agricultural land and analyzed for physico-chemical properties and metal accumulation in different parts of the plants. The comparison of the data of physico-chemical properties of control and contaminated soil showed that salinity, electrical conductivity, available phosphorous, sodium and potassium content (both water soluble and exchangeable) were found high in contaminated soil. The analysis of plant available metal content in the soil showed the highest level of Fe, which ranged from 529.02 to 2615 μg g⁻¹ dw and lowest level of Ni (3.12 to 10.51 μg g⁻¹ dw). The analysis of the results revealed that accumulation of toxic metal Cr in leafy vegetables was found more than fruit bearing vegetables/crops. Thus, it is recommended that the leafy vegetables are unsuitable to grow in such contaminated sites. It is important to note that toxic metal, Ni was not detected in all the plants. The edible part of the vegetables (under ground) such as, garlic (19.27 μg g⁻¹ dw), potato (11.81 μg g⁻¹ dw) and turmeric (20.86 μg g⁻¹ dw) has accumulated lowest level of toxic metal, Cr than leafy and fruit bearing vegetables. In some fruit part of vegetables such as, bitter gourd, egg plant, jack tree, maize and okra, the accumulation of Cr was not detected and may be grown in this area.     

Pattern of Hexa-Valent Chromium in Air Borne Respirable Dust Generated at Various Workplaces in Opencast Chromite Mines

The paper presents a study into air borne respirable dust (ARD) concentration at various workplaces in two open cast chromite mines of Sukinda chromite belt, India. One of these mines is mechanised and the other one is semi-mechanised. The study has been conducted in three phases and ARD concentration has been measured at various workplaces in both the mines. Apart from the determination of ARD concentration, the dust samples collected on filter papers were analysed for hexa-valent chromium by colorimetric method and Cr(VI) direct absorption measurement. In addition, the particle size ranges in ARD have been determined by using cascade impactor fitted onto high volume samplers and laser guided particle size analyser. The paper finally presents a comparison between ARD concentration vis-à-vis the presence of hexa-valent chromium concentration in collected samples of both mechanised and semi-mechanised mines.