Biochemical alterations due to acute tannery effluent toxicity in Lemna minor L.

The effect of acute tannery effluent (TE) toxicity on some biochemical parameters in Lemna minor L. was studied using different TE concentrations i.e. 0 to 50.0% (v/V) in modified Hoagland's solution and exposure durations of 48 and 96 hours. The L. minor plants failed to survive at TE levels beyond 25.0%. The photosynthate­ (starch) level increased above the control up to the 10.0% TE level, at higher concentrations it decreased to a level below the control and was comparatively higher at 96-hour exposure. Reducing sugar content at 48 hours did not show a clear trend but at 96 hours it followed a clear increasing trend up to 5.0% effluent level and subsequent concentrations showed decrease in reducing sugars. In the case of total soluble sugars at 48 hours, there was an increase up to 10.0% effluent after which it started decreasing till 25.0% level. However, at 96-hour exposure, total soluble sugars were maximum in control and showed a steady decreasing trend with increasing TE concentrations. The soluble proteins increased and were higher than the control at 48 hour exposure. However, 96 hour exposure to 20.0 and 25.0% effluent concentration revealed a marked decrease in soluble protein content. Total free amino acid content followed the trend observed with soluble protein up to 20.0% effluent level, after which their content decreased markedly. The acid phosphatase activity was higher at 48-hour exposure in comparison to 96 hour and showed an increasing trend with increasing effluent concentration at both the exposures. These biochemical constituents can be used as indices for measuring the phytotoxicity and understanding the mechanism and the level of tolerance to tannery effluent in L. minor

An Overview of Nickel (Ni2+) Essentiality, Toxicity and Tolerance Strategies in Plants

Heavy metals (HMs) toxicity has an unavoidable threat to environment and public health due to their increasing contamination and accumulation in atmosphere which ultimately passes to the living beings by the route of food chain. Heavy metals are increasing rapidly in soil and water by weathering of rocks and anthropogenic activities and are now emerging as a major health hazard to humans and plants. Among them Nickel (Ni2+) is a controversial element because of debate on its essentiality or non-essentiality in plants. Ni2+ is an important constituent (micronutrient) of many metallo-enzymes including urease, Ni-Fe hydrogenase, Ni-superoxide dismutase etc. while at higher level it affects all cellular and metabolic processes and causes retardation of germination, competition with other essential metal ions, osmotic imbalance, alteration of many enzymatic activities, disruption of cell structure and wilting, reduced photosynthetic activity, oxidative stress etc. Plants also possess some natural and stress-induced strategies to cope up with Ni2+ excess/toxicity. These strategies include growth regulators, antioxidative enzymes, amino acids as osmoprotectant, and chelation of Ni2+ with metalloproteins and metallothionins. This review focuses on researches done on the morpho-biochemical alterations induced by elevated Ni2+ concentration in plants and as well as the strategies adapted by plants to survive and neutralize the effects of these alterations

The effects of simulated acid rain of different pH-levels on biomass and leaf area in Sunflower (Helianthus annuus)

The effects of simulated acid rain (SAR) of different pH [distilled water-7.0 (control), 5.7, 4.5 and 3.0] were studied using sunflower (Helianthus annuus) cv. ‘Morden’ as test system. Sunflower plants were sprayed with 30 ml acid rain solution at weekly intervals starting from two leaved stage till initiation of flowering in the early morning under natural environment. Evaluation of SAR effects on plant roots, shoots and leaves at peak growth and maturity stages revealed that biomass and lengths of the studies plant parts decreased with decreasing pH of acid rain solution. Comparison of biomass and length at peak growth and maturity stages recorded maximum difference in control the difference narrowed with increasing acidity. The differences at acidic treatments were well-marked with leaves followed by roots and shoots, respectively. In case of length, roots and shoots were more adversely affected as compared to leaves. Acid rain application caused reduction in leaf area which has direct bearing on growth of roots and shoots, and overall plant growth. Effects of SAR on sunflower increased more dramatically with the increase of SAR acidity and were correlated with exposure times and doses of SAR. The study indicates the sunflower plant to be an acid rain sensitive system and demands for breeding acid rain tolerant varieties in view of growing industrialization and expanding acid rain geographical areas

Comprehensive Study of 3-Level Stabilizer in Hybrid PV and Wind Energy Systems- A Review

When variables are bounded so that almost the whole constraints are satisfied, power system stability is typically characterized as an electric power system's ability to restore a situation of functioning equilibrium after being subjected to a physical disturbance.This paper presents a thorough investigation of three-level stabilizers in a hybrid PV Wind Energy system that is integrated with the power system. From a hybrid renewable energy system that is linked to the grid and studied with a stabilizer that uses a variety of control algorithms based on artificial intelligence algorithms developed by several researchers

A Multi-Spacecraft View of Solar-Energetic-Particle Onsets in the 1977 November 22 Event

We examine the onset timing of solar energetic particles (SEPs) in the large ground-level event (GLE) of 1977 November 22 as observed from six spacecraft at four distinct solar longitudes. In most cases, it was possible to use velocity dispersion of the energetic protons to fix the solar particle release (SPR) time and the path-length traveled by the initial particle burst from each solar longitude. We find that the SPR times do depend upon solar longitude, being earliest for spacecraft that are magnetically well-connected to the source region, and later for longitudes on the flanks of the outward driven shock wave. The earliest SPR time occurs well after peak photon emission from the associated Ha flare. These observations are consistent with conclusions derived from single-longitude observations of different GLE events