Muhammad Jamil Khan

The Potential Use of Vetiveria zizanioides for the Phytoremediation of Antimony, Arsenic and Their Co-Contamination

Antimony (Sb) and arsenic (As) contaminations are the well reported and alarming issues of various contaminated smelting and mining sites all over the world, especially in China. The present hydroponic study was to assess the capacity of Vetiveria zizanioides for Sb, As and their interactive accumulations. The novelty of the present research is this that the potential of V. zizanioides for Sb and As alone and their interactive accumulation are unaddressed. This is the first report about the interactive co-accumulation of Sb and As in V. zizanioides. Highest applied Sb and As contaminations significantly inhibited the plant growth. Applied Sb and As alone significantly increased their concentrations in the roots/shoot of V. zizanioides. While co-contamination of Sb and As steadily increased their concentrations, in the plant. The co-contamination of Sb and As revealed a positive correlation between the two, as they supplemented the uptake and accumulation of each other. The overall translocation (TF) and bioaccumulation factors (BF) of Sb in V. zizanioides, were 0.75 and 4. While the TF and BF of As in V. zizanioides, were 0.86 and 10. V. zizanioides proved as an effective choice for the phytoremediation and ecosystem restoration of Sb and As contaminated areas.

Trace Elements in Abiotic Stress Tolerance

Trace elements are minutely required elements for normal growth and functioning of biological systems. They perform several intricate roles in complex cellular phenomena including plant protection against stress conditions. The role of various trace elements in enhancing plant’s tolerance to abiotic stresses is multifaceted. At primary level, they are the constituents of cell organelles and membranes and serve as metalloproteins and metal cofactors or activating agents for key ROS scavenging enzymes. At secondary level, they regulate key metabolic pathways involved in gene expression; biosynthesis of proteins, carbohydrates, and lipids; and production of phytohormones which protect plants from ROS-induced injury. The role of some important individual trace elements in enhancing plant’s tolerance to various abiotic stresses is explained here in different plant species.

Impact of Pollutants on Paddy Soil and Crop Quality

Paddy soils, used most often for rice cultivation, are flooded and submerged soils that exhibit prominent set of properties as result of extensive saturation. Among these, redox potential (Eh) and pH fluctuations are the most important characteristics of paddy soils indicating variation in oxidation-reduction reactions of soil components like oxygen (O2), nitrogen (N), iron (Fe), manganese (Mn), sulfur (S), and carbon (C). Reckless use of inorganic fertilizers and pesticides and irrigation with polluted water for intended rice crop yields have raised heavy metal pollution problems especially lead, cadmium, and arsenic in soil environment. Besides, various macro- and micronutrients including nitrogen and potassium and excess of salt water and fluorine also negatively affect the crop quality and yield. Accumulation of heavy metals and other pollutants in soil and their introduction in food chain through uptake by rice and vegetables are of major concern. Therefore, management practices including artificial submergence, plowing, puddling, organic manuring, leveling, liming, and fertilization play vital role in development of paddy soils. Various techniques are adopted for remediation of polluted paddy soil that includes excavation, chemical stabilization, soil washing, phytoremediation, and thermal desorption. Further investigations are required for identification of soil flora and fauna for remediation purposes.

Mechanisms of Cr(VI) resistance by endophytic Sphingomonas sp. LK11 and its Cr(VI) phytotoxic mitigating effects in soybean (Glycine max L.)

Chromium Cr(VI) is highly toxic and leads to impaired phenotypic plasticity of economically important crops. The current study assessed an endophytic-bacteria assisted metal bio-remediation strategy to understand stress-alleviating mechanisms in Glycine max L (soybean) plants inoculated with Sphingomonas sp. LK11 under severe Cr(VI) toxicity. The screening analysis showed that high Cr concentrations (5.0 mM) slightly suppressed LK11 growth and metal uptake by LK11 cells, while significantly enhancing indole-3-acetic acid (IAA) production. Endophytic LK11 significantly upregulated its antioxidant system compared to control by enhancing reduced glutathione (GSH), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activities to counteract Cr-induced oxidative stress. Cr toxicity induced cell morphological alteration, as shown by SEM-EDX analysis and triggered significant lipid peroxidation. The interaction between LK11 and soybean in Cr-contaminated soil significantly increased plant growth attributes and down-regulated the synthesis of endogenous defense-related phytohormones, salicylic acid and abscisic acid, by 20% and 37%, respectively, and reduced Cr translocation to the roots, shoot, and leaves. Additionally, Cr-induced oxidative stress was significantly reduced in LK11-inoculated soybean, regulating metal responsive reduced GSH and enzymatic antioxidant CAT. Current findings indicate that LK11 may be a suitable candidate for the bioremediation of Cr-contaminated soil and stimulation of host physiological homeostasis.

Sugar industry press mud as alternate organic fertiliser source

* Corresponding author Abstract: Organic materials are added to soil for improving soil physico-chemical properties. In the present study different doses of press mud along with NPK were applied to wheat crop in pot and field experiments. The increasing levels of press mud application improved soil physical conditions like increase in total porosity and reduced bulk density. Organic matter content, NPK, Fe, Mn, Zn and Cu content in soil also increased with the press mud application. ECe, pH and exchangeable Na percentage were reduced. Increasing levels of press mud application also increased wheat yield, yield components and crop nutrient utilisation. For realising near maximum wheat yield (95% relative yield) 40 tonnes press mud per ha −1 was found to be the optimum level.