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Cadmium (Cd) in soil–plant system can abridge plant growth by initiating alterations in root zones. Hydroponics and rhizoboxes are useful techniques to monitor plant responses against various natural and/or induced metal stresses. However, soil based studies are considered more appropriate in order to devise efficient food safety and remediation strategies. The present research evaluated the Cd-mediated variations in elemental dynamics of rhizospheric soil together with in planta ionomics and morpho-physio-biochemical traits of two differentially Cd responsive maize cultivars. Cd-sensitive (31P41) and Cd-tolerant (3062) cultivars were grown in pots filled with 0, 20, 40, 60 and 80 µg/kg CdCl2 supplemented soil. The results depicted that the maize cultivars significantly influenced the elemental dynamics of rhizosphere as well as in planta mineral accumulation under applied Cd stress. The uptake and translocation of N, P, K, Ca, Mg, Zn and Fe from rhizosphere and root cell sap was significantly higher in Cd stressed cv. 3062 as compared to cv. 31P41. In sensitive cultivar (31P41), Cd toxicity resulted in significantly prominent reduction of biomass, leaf area, chlorophyll, carotenoids, protein contents as well as catalase activity in comparison to tolerant one (3062). Analysis of tolerance indexes (TIs) validated that cv. 3062 exhibited advantageous growth and efficient Cd tolerance due to elevated proline, phenolics and activity of antioxidative machinery as compared to cv. 31P41. The cv. 3062 exhibited 54% and 37% less Cd bio-concentration (BCF) and translocation factors (TF), respectively in comparison to cv. 31P41 under highest Cd stress regime. Lower BCF and TF designated a higher Cd stabilization by tolerant cultivar (3062) in rhizospheric zone and its potential use in future remediation plans.

Cadmium (Cd) is highly toxic metal for plant metabolic processes even in low concentration due to its longer half-life and non-biodegradable nature. The current study was designed to assess the bioremediation potential of a Cd-tolerant phytobeneficial bacterial strain Bacillus sp. SDA-4, isolated, characterized and identified from Chakera wastewater reservoir, Faisalabad, Pakistan, together with spinach (as a test plant) under different Cd regimes. Spinach plants were grown with and without Bacillus sp. SDA-4 inoculation in pots filled with 0, 5 or 10 mg kg−1 CdCl2-spiked soil. Without Bacillus sp. SDA-4 inoculation, spinach plants exhibited reduction in biomass accumulation, antioxidative enzymes and nutrient retention. However, plants inoculated with Bacillus sp. SDA-4 revealed significantly augmented growth, biomass accumulation and efficiency of antioxidative machinery with concomitant reduction in proline and MDA contents under Cd stress. Furthermore, application of Bacillus sp. SDA-4 assisted the Cd-stressed plants to sustain optimal levels of essential nutrients (N, P, K, Ca and Mg). It was inferred that the characterized Cd-tolerant PGPR strain, Bacillus sp. SDA-4 has a potential to reduce Cd uptake and lipid peroxidation which in turn maintained the optimum balance of nutrients and augmented the growth of Cd-stressed spinach. Analysis of bioconcentration factor (BCF) and translocation factor (TF) revealed that Bacillus sp. SDA-4 inoculation with spinach sequestered Cd in rhizospheric zone. Research outcomes are important for understanding morpho-physio-biochemical attributes of spinach-Bacillus sp. SDA-4 synergy which might provide efficient strategies to decrease Cd retention in edible plants and/or bioremediation of Cd polluted soil colloids.

In the present study, geologic lineaments have been extracted by automatic lineament extraction algorithm of Geomatica software, using digital elevation model (DEM) derived shaded relief images being illuminated with multiple illumination directions. Fieldwork has been carried out for ground truth and in search of any possible evidence of movement along the extracted lineaments in the Kandiah valley in Kohistan district. A regional lineament (possible fault) has been inferred in recent a geological study (e.g. Zeilinger, 2002) that has been found to cross the Kandiah valley. The analysis and ground verification of automatic extracted geologic lineaments revealed that Kandiah valley is in one block without having any regional geological lineament. However, a good correlation was found among the predominant orientations of extracted geologic lineaments and the measured trends of rock features such as rock foliation, drainage pattern and linear ridges. Based on extracted lineaments, no pronounced lineament or fault with the regional extension was identified. This finding is consistent with the field observations as no defenite evidence of fault was found in the study area.

The gene encoding copper-dependent laccase from Bacillus subtilis strain R5 was cloned and expressed in Escherichia coli. Initially the recombinant protein was produced in insoluble form as inclusion bodies. Successful attempts were made to produce the recombinant protein in soluble and active form. The laccase activity of the recombinant protein was highly dependent on the presence of copper ions in the growth medium and microaerobic conditions during protein production. The purified enzyme exhibited highest activity at 55 °C and pH 7.0. The recombinant protein was highly thermostable, albeit from a mesophilic source, with a half-life of 150 min at 80 °C. Similar to temperature, the recombinant protein was stable in the presence of organic solvents and protein denaturants such as urea. Furthermore, the recombinant protein was successfully utilized for the degradation of various synthetic dyes reflecting its potential use in treatment of wastewater in textile industry. Abbreviations: ABTS,2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid; CBB, Coomassie brilliant blue; SGZ, syringaldazine; DMP, 2,2-dimethoxy phenol.

The geological and geographical conditions have made the Himalayas one of the regions most vulnerable to disasters. Northern Pakistan is made up of high-relief Himalayan mountains where landslides are the most frequently occurring catastrophic events. Floods, earthquakes, and landslides occur most often in this region, causing deaths and severe infrastructure damages. The studied area is experiencing significant landslide events triggered by destructive seismic activity, extreme seasonal rainfalls, and human activities. In this study, landslide susceptibility mapping is proposed using an integrated model of information value method by optimizing its capabilities and overcoming its limitations to enhance both precision and accuracy of the results. This approach quantifies and estimates the probability of landslide occurrence using statistical principles and techniques. Seven distinct landslide causative factors, including slope angle, distance to stream, drainage density, distance to road, land cover, normalized difference vegetation index, lithology, and distance to faults were evaluated to determine the areas at risk for future slope movements. A reliable landside inventory from a spatial database combined with ground-truthing field surveys was prepared for evaluating the relationship between the landslides and their causative factors. The accuracy and efficiency of the developed model are evaluated using sensitivity analysis of the receiver operator curve (ROC). The ROC-validated results showed an accuracy of 0.845 for model prediction rate and an accuracy of 0.837 for model success rate, indicating that the model is reliable to produce landslide susceptibility map. The results showed the reasonable efficiency of the applied method for assessing landslide susceptibility in the study area and applicable to other regions with similar geomorphological conditions.

Cadmium (Cd) is highly toxic for plant metabolic processes even in low concentration due to higher retention rates, longer half-life and non-biodegradable nature. The current study was designed to assess the bioremediation potential of Cd tolerant PGPR, Serratia sp. CP-13 together with two differentially Cd tolerant maize cultivars (MMRI-Yellow, Sahiwal-2002) selected amongst ten cultivars after screening. The maize cultivars were grown under different Cd treatments (0, 6, 12, 18, 24, 30 µM) in Petri plates both with and without Serratia sp. CP-13 inoculation. Treated plants were analyzed for their biomass accumulation, chlorophylls, carotenoids, proline, anthocyanin, protein, malondialdehyde (MDA), H2O2 as well as for antioxidants (POD, SOD, CAT) and mineral elements (Ca, Mg, Zn, K, Fe, Na, Cd). The maize cultivar MMRI-Yellow (tolerant) and Sahiwal-2002 (sensitive) exhibited significant reduction in leaf area, nutrient contents, plant biomass, activity of antioxidants, total proteins, photosynthetic pigments as well as flavonoids with increased production of H2O2, proline, MDA and relative membrane permeability (RMP) under Cd stress. However, this reduction was cultivar specific and recorded higher in cv. Sahiwal-2002 as compared to MMRI-Yellow. Application of Serratia sp. CP-13 significantly augmented plant biomass, photosynthetic pigments, antioxidative machinery, as well as flavonoids and proline while diminishing H2O2, RMP MDA production even under Cd stress in studied cultivars. Furthermore, CP-13 inoculation assisted the Cd stressed plants to sustain an optimal level of essential nutrients (Ca, Mg, Zn, K, Fe) except for Na and Cd which responded antagonistically. It was inferred that both inoculated maize cultivars exhibited better health and metabolism but substantial Cd tolerance was acquired by the sensitive cv. Sahiwal-2002 than the tolerant cv. MMRI-Yellow under applied Cd regimes. Furthermore, studied maize cultivars depicted maximum Cd tolerance in order of 30

The accumulation of cadmium (Cd) in edible plant parts and fertile lands is a worldwide problem. It negatively influences the growth and productivity of leafy vegetables (e.g., spinach, Spinacia oleracea L.), which have a high tendency to radially accumulate Cd. The present study investigated the influences of peptone application on the growth, biomass, chlorophyll content, gas exchange parameters, antioxidant enzymes activity, and Cd content of spinach plants grown under Cd stress. Cd toxicity negatively affected spinach growth, biomass, chlorophyll content, and gas exchange attributes. However, it increased malondialdehyde (MDA), hydrogen peroxide (H2O2), electrolyte leakage (EL), proline accumulation, ascorbic acid content, Cd content, and activity of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in spinach plants. The exogenous foliar application of peptone increased the growth, biomass, chlorophyll content, proline accumulation, and gas exchange attributes of spinach plants. Furthermore, the application of peptone decreased Cd uptake and levels of MDA, H2O2, and EL in spinach by increasing the activity of antioxidant enzymes. This enhancement in plant growth and photosynthesis might be due to the lower level of Cd accumulation, which in turn decreased the negative impacts of oxidative stress in plant tissues. Taken together, the findings of the study revealed that peptone is a promising plant growth regulator that represents an efficient approach for the phytoremediation of Cd-polluted soils and enhancement of spinach growth, yield, and tolerance under a Cd-dominant environment.

The study area is covered by alluvium having average thickness of about 200 m that is underlain by the Precambrian basement rock units including iron ore to be mined in future. In this regards, necessary campaign of subsurface investigations including both geotechnical and hydrogeological has been carried. In geotechnical investigations, disturbed and undisturbed samples were collected from five (5) boreholes and hydrological investigations by using water pump out test were conducted to determine the characteristics of aquifer. Rock samples were also collected from already drilled boreholes for iron ore estimation from a depth of more than 200 m. The laboratory testing has classified alluvium as silty sand/sandy silt (SP-SM/SM) and clayey silt/non-plastic silt (CL-ML/ML) as per soil classification criteria having angel of friction of 31.4 - 38.5 degree with bulk density of 1.461 - 1.853 g/cc. The initial void ratio (eo) varies from 0.412 to 0.952 with no swell potential in consolidation tests. The chemical analyses of the soil have indicated values of 0.003% - 0.006%, 0.0012% - 0.0057%, 0.013% - 0.030% sulphate, chloride and organic matter contents respectively with pH-value of 6.92 - 7.56. The strength of the underlying rock was found to be medium strong to very strong corresponding to values of 25 - 140 MPa in uniaxial compression and indirect tensile strength of 15.66 MPa. Hydrological study reveals that aquifer is unconfined and generally isotropic in nature. The average transmissivity, hydraulic conductivity and storage coefficient are 6038 m2/day, 4.0 × 101 m/day and 0.016, respectively that presented aquifer is quite permeable. The cone of influence covered area of 65 m from main production well. For the open pit mining operation, stability analysis is performed by assuming a 4V:1H slope in the bedrock while 1V:1H in the overlying sediments cover using Limit-Equilibrium (LE) analysis in Slide computer program. However, overburden slope was concluded to be unstable with the analyzed slope angle. The deformation analysis for mine slopes by finite element method was performed using Phase 2 (RS) software. The results show maximum deformation is likely to be in order of as high as 700 mm for individual slope riser whereas in the range of 300 to 400 mm for the overall slope.

In the above published article in October 2018 issue of the Journal of the Geological Society of India (v.92, pp.465–470).

Petrophysical evaluation and rock physics analysis are the important tools to relate the reservoir properties like porosity, permeability, pore fluids with seismic parameters. Nevertheless, the uncertainties always exist in the quantification of elastic and seismic parameters estimated through wireline logs and rock physics analysis. A workflow based on statistical relationships of rock physics and logs derived elastic and seismic parameters with porosity and the percentage error exist between them is given. The statistical linear regressions are developed for early Eocene Chorgali Formation between various petrophysically factors determined from borehole logging of well Ratana–03 drilled in tectonically disturbed zone and the seismic and elastic parameters estimated through rock physics modeling. The rock physics constraints such as seismic velocities, effective density and elastic moduli calculated from Gassmann fluid substation analysis are in harmony and close agreement to those estimated from borehole logs. The percentage errors between well logs and rock physics computed saturated bulk modulus (K sat ), effective density (ρ eff ), compressional and shear wave velocities (V P and V S) are 1.31%, 4.23 %, 5.25% and 4.01% respectively. The permeability of reservoir intervals show fairly strong linear relationship with the porosity, indicating that the reservoir interval of the Chorgali Formation is permeable and porous thus having large potential of hydrocarbon accumulation and production.

This study presents a detailed geological and geotechnical analysis of Dewal landslide along Murree-Muzaffarabad road, Pakistan. The study area is situated in a tectonically active region of the earth where mass movements like rock fall, rockslides and slumps cause adverse economic loss through disruption of travelling on roads. The study has the main focus on factors responsible for its instability together with stability analysis using limit equilibrium method by use of computer program Slide (version 5.0). The input parameters of rock mass was evaluated by field investigations and laboratory testing. To analyze the net deposit and net slide mass of the landslide area, multi-date point’s data of 2008 and 2012 of the slide area was obtained and their digital elevation models were generated by using Inverse distance weighting (IDW) technique in ArcGIS 9.3. The study has concluded that the present slope instability is the function of a specific deformation pattern in the rock units (leading towards the possibility of a shear plane under the slid mass), surface and subsurface drainage and the engineering behavior of the overburden and underlying rock units. This study recommends several protection parameters for landslide and suggests that detailed investigation of Dewal landslide is required for long term stability.

Conglomeratic rocks are composed of macro-particles (varying in size from gravels to cobbles and boulders with diameter greater than 2 mm) bonded by fine-grained cement particles with diameters of

This paper encompasses the engineering geological properties of rock mass along the power tunnel of hydropower in Kohistan, Khayber Pakhtun Khawa (KPK), Pakistan. The major geological units of the study area are Chilas complex (CC) and Gilgit complex (GC) that consists mostly of igneous and metamorphic rocks. Discontinuity surveys were conducted to classify the rock mass by utilizing rock mass rating (RMR) and tunneling quality index (Q) classification systems. RMR system involves collection of data for parameters of rock strength, RQD, spacing of discontinuities, condition of discontinuities, groundwater condition and Q system involves rock quality designation (RQD), joint roughness (Jr), joint sets (Js), joint alteration (Ja), stress reduction factor (SRF) and joint water reduction (Jw). RMR values ranges from 46 to 66 (fair to good) for rock unit of Chilas complex (CC) and 50 to 58 (fair) for rock unit of Gilgit complex (GC). The evaluated values of tunnel quality by Q-system are 1.55 to 6.4 (poor to fair) for Chilas complex (CC) and 1.35 to 1.84 (poor) for Gilgit complex (GC). The required support along the tunnel route is also estimated by both classification systems. Unwedge program is used to analyze the unstable zones due to the intersection of different joint sets. Total 14 cases are analyzed in Unwedge from which 3 cases have failure potential with FOS less than 1. These failure potential blocks can become stable by applying further support of rock bolting and shotcrete layer.

The pivotal aim of this study is to evaluate the rock mass characterization and deformation modulus. It is vital for rock mass classification to investigate important parameters of discontinuities. Therefore, Rock Mass Rating (RMR) and Tunneling quality index (Q) classification systems are applied to analyze 22 segments along proposed tunnel routes for hydropower in Kandiah valley, Khyber Pakhtunkhwa, Pakistan. RMR revealed the range of fair to good quality rocks, whereas Q yielded poor to fair quality rocks for investigated segments of the rock mass. Besides, Em values were acquired by empirical equations and computer-aided program RocLab, and both methods presented almost similar variation trend of their results. Hence, the correlations of Em with Q and RMR were carried out with higher values of the regression coefficient. This study has scientific significance to initially understand the rock mass conditions of Kandiah valley.

Lead (Pb) stress adversely affects in planta nutrient homeostasis and metabolism when present at elevated concentration in the surrounding media. The present study was aimed at investigation of organic acid exudations, elemental contents, growth, and lipid peroxidation in two wild plants (Amaranthus viridis L. and Portulaca oleracea L.), exhibiting differential root to shoot Pb translocation, under Pb stress. Plants were placed in soil spiked with lead chloride (PbCl2) concentrations of 0, 15, 30, 45, or 60 mg Pb/kg soil, in rhizoboxes supplied with nylon nets around the roots. The plant mucilage taken from root surfaces, mirroring the rhizospheric solution, was analyzed for various organic acids. Lead stress resulted in a release of basified root exudates from both plants. Exudates of P. oleracea roots showed a higher pH. In both plants, the pH rising effect was diminished at the highest Pb treatment level. The exudation of citric acid, glutamic acid (in both plants), and fumaric acid (in P. oleracea only) was significantly increased with applied Pb levels. In both plant species, root and shoot Pb contents increased while nutrients (Ca, Mg, and K) decreased with increasing Pb treatment levels, predominantly in A. viridis. At 60 mg Pb/kg soil, shoot Na content of A. viridis was significantly higher as compared to untreated control. Higher Pb treatment levels decreased plant fresh and dry masses as well as the quantity of photosynthetic pigments due to enhanced levels of plant H2O2 and thiobarbituric acid reactive substances in both species. Photosynthetic, growth, and oxidative stress parameters were grouped into three distinct dendrogram sections depending on their similarities under Pb stress. A positive correlation was identified between Pb contents of studied plants and secretion of different organic acids. It is concluded that Pb stress significantly impaired the growth of A. viridis and P. oleracea as a result of nutritional ion imbalance, and the response was cultivar-specific and dependent on exogenous applied Pb levels. Differential lipid oxidation, uptake of nutrients (Ca, Mg, and K) and exudation of citric acid, fumaric acid, and glutamic acid could serve as suitable physiological indicators for adaptations of P. oleracea to Pb enriched environment. The findings may help in devising strategies for Pb stabilization to soil colloids.

Lead (Pb) is highly toxic to plants because it severely affects physiological processes by altering nutrient solution pH. The current study elucidated Pb-induced changes in nutrient solution pH and its effect on physiology of two Solanum melongena L. cultivars (cv. Chuttu and cv. VRIB-13). Plants were grown in black plastic containers having 0, 15, 20, and 25 mg L−1 PbCl2 in nutrient solutions with starting pH of 6.0. pH changes by roots of S. melongena were continuously monitored for 8 days, and harvested plants were analyzed for physiological and biochemical attributes. Time scale studies revealed that cv. Chuttu and cv. VRIB-13 responded to Pb stress by causing acidification and alkalinization of growth medium during the first 48 h, respectively. Both cultivars increased nutrient solution pH, and maximum pH rise of 1.21 units was culminated by cv. VRIB-13 at 15 mg L−1 Pb and 0.8 units by cv. Chuttu at 25 mg L−1 Pb treatment during the 8-day period. Plant biomass, photosynthetic pigments, ascorbic acid, total amino acid, and total protein contents were significantly reduced by Pb stress predominantly in cv. Chuttu than cv. VRIB-13. Interestingly, chlorophyll contents of cv. VRIB-13 increased with increasing Pb levels. Pb contents of roots and shoots of both cultivars increased with applied Pb levels while nutrient (Ca, Mg, K, and Fe) contents decreased predominately in cv. Chuttu. Negative correlations were identified among Pb contents of eggplant roots and shoots and plant biomasses, leaf area, and free anthocyanin. Taken together, growth medium alkalinization, lower root to shoot Pb translocation, and optimum balance of nutrients (Mg and Fe) conferred growth enhancement, ultimately making cv. VRIB-13 auspicious for tolerating Pb toxicity as compared with cv. Chuttu. The research outcomes are important for devising metallicolous plant-associated strategies based on plant pH modulation response and associated metal uptake to remediate Pb-polluted soil.

Petrographic and mechanical properties of early Eocene Sakesar limestone have been investigated to establish the relationship between these parameters. Microscopic study revealed the presence of micrite (51.38%), sparite (12.90%), dolomite (12.95%), and allochems (20.88%) in the limestone samples. The strength parameters such as unconfined compressive strength (UCS), point load test (PLT), and Schmidt rebound hammer values (R n ) were determined in the rock mechanics laboratory. Regression analyses were carried out to establish correlation between limestone constituents and the strength parameters. The UCS and other mechanical properties showed moderate inverse relationship with sparite and allochems, whereas micrite and dolomite indicate a positive correlation with UCS. To get significant correlations for cumulative micrite + dolomite and sparite + allochems, percentages and strength parameters were arranged in decreasing order. The fixed threshold for the cumulative values of micrite and dolomite were ≥80, 70–80, 60–70, 50–60 and

Triacontanol (TRIA) has been shown to regulate growth in some crop species exposed to stressful environments. In the present study, we assessed whether or not and to what extent foliar-applied TRIA can alter metabolism and nutrient uptake, and thus induce salt tolerance in maize (Zea mays L.). For this purpose, 14-day-old plants of two maize cultivars (MMRI-Yellow and Hybrid S-515) were subjected to salt stress (0 mM and 100 mM NaCl). 21-day-old plants were exogenously treated with different concentrations (0, 2, 5 µM) of TRIA. After 51 days of TRIA treatment (72-day-old plants), data of various attributes were collected. Generally, salt stress negatively affected the growth attributes in both maize cultivars. Furthermore, salinity increased relative membrane permeability (RMP), malondialdehyde (MDA), total soluble protein contents, free proline and sodium (Na+) contents, and the activities of peroxidase (POD) and catalase (CAT) in both maize cultivars. Foliar spray of TRIA enhanced growth, soluble proteins, nitrate reductase (NR) activity, total phenolics, and free proline and shoot K+ contents, while it decreased RMP and root Na+ contents in maize. Overall, cv. MMRI-Yellow showed greater tolerance to salinity compared with Hybrid S-515. Among the various TRIA levels, 5 µM was much more effective in increasing growth of maize plants under both normal and saline regimes.

Coal is the vital source of energy in world and is a burnable brownish black or black sedimentary rock contemporary in the rock strata in form of layers; thickness of layers may vary. It is available in all over the world in large quantities and can be extracted to be utilized as energy-producing source to fulfill the energy demand. There are two modes of mining: (a) surface or open pit mining and (b) underground mining. The method of excavation adopted depends on a number of factors including depth of deposition and inclination angle of the coal seam. The workers involved in this operation are prone to more risk than the workers who are involved in other operations. Miners face numerous problems in the process of underground coal extraction such as high temperature, humidity, coal and silica dusts, harmful gases, the rock stresses, and the disturbance due to extraction that causes failures. These problems cause injuries, multifatalities, and major asset losses until precautions are taken to control these problems. Coal mine failures are affected by various factors such as geological and structural parameters. The in situ conditions of the rocks in the coal mines are disturbed due to excavation and extraction of coal. In order to stabilize the roof as well as walls of the coal mines, different techniques are used. The most common techniques of supports in coal mines include can support, pump-able roof support, cluster prop, timber support, prop, shotcrete, wire mash, and rock bolts.

Evaluation of the strength of rockmass is very important to ensure the safety of the structures. The uniaxial compressive strength test (UCS), point-load index strength test (Is50), Schmidt rebound hammer test (SRHN), tensile strength test (Ts), velocity test (Vp) and density have been commonly used for characterisation of the rockmass. The UCS is comparably expensive and time taking than other strength tests. Therefore, these tests have been correlated by various researchers for ease of evaluating the rock properties such as UCS. This study aims to correlate the UCS with Is50, Vp, SRHN, Ts and density. The core samples were collected from different boreholes locations in the Salt Range, Pakistan. The lithology of the core samples was mainly Limestone of the Chorgali formation. Samples were prepared as per the ISRM standards. Afterwards, the strength tests have been performed in a laboratory followed by correlation of the UCS with Is50, Vp, SRHN, Ts and density. Then estimation capability of these correlations was checked by plotting actual UCS against the UCS estimated by correlation established. Plotted values were checked with reference to 1:1 diagonal. On the basis of which, it was concluded that all correlation were reasonable except UCS versus Is50 axial and UCS versus SRHN axial. The Is50 axial overestimated the UCS because of vertical variation in the lithology from limestone to argillaceous limestone while the SRHN axial underestimated the UCS value because of low rebound due to bedding surfaces encountered. It has been found that the data was scattered and the value of coefficient of variance was considerably high ranging from 29 to 59. These variations in the data were mainly due to mineralogical variation in the Chorgali Formation from limestone to argillaceous limestone.

The phyllosphere and rhizosphere of plants have been a reservoir of microorganisms of both symbiotic and pathogenic nature. The interplay between plants and associated microbes involves complex and dynamic mechanisms, many of which are unexplored. The unraveling of these mechanisms is a big challenge for plant biologists. The consequence of such interactions may be beneficial, detrimental, or neutral for the hosts. There are many known mechanisms through which microorganisms especially bacteria support plant growth, i.e., fixation of atmospheric nitrogen, solubilization of inorganic phosphate, modulated phytohormones synthesis, production of stress-responsive enzymes like 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, and biocontrol of many plant diseases. Both above- and underground plant organs are frequently exposed to a plethora of microorganisms, including viruses, bacteria, oomycetes, fungi, and eukaryotic protozoans. Phytopathogens defend their habitat and infect plants by a variety of compounds (toxins) that are broad spectrum in their activity. In response, plants initiate defensive mechanisms that resist pathogen penetration and subsequent infection. Thus, various events of molecular crosstalk take place between plants, and both friendly and hostile microbes trigger a series of highly dynamic plant cellular responses. Such mechanisms are very crucial for pathogen recognition and induction of adequate defense signal transduction cascades in the plant. More research insights are required to unravel the molecular basis behind these mechanisms. Also, to support the plant life, many complex mechanisms initiated after the association of symbiotic or pathogenic microorganisms need to be explored.

Our earlier work described that the roots of two maize cultivars, grown hydroponically, differentially responded to cadmium (Cd) stress by initiating changes in medium pH depending on their Cd tolerance. The current study investigated the root exudation, elemental contents and antioxidant behavior of the same maize cultivars [cv. 3062 (Cd-tolerant) and cv. 31P41 (Cd-sensitive)] under Cd stress. Plants were maintained in a rhizobox-like system carrying soil spiked with Cd concentrations of 0, 10, 20, 30, 40 and 50 μmol/kg soil. The root and shoot Cd contents increased, while Mg, Ca and Fe contents mainly decreased at higher Cd levels, and preferentially in the sensitive cultivar. Interestingly, the K contents increased in roots of cv. 3062 at low Cd treatments. The Cd stress caused acidosis of the maize root exudates predominantly in cv. 3062. The concentration of various organic acids was significantly increased in the root exudates of cv. 3062 with applied Cd levels. This effect was diminished in cv. 31P41 at higher Cd levels. Cd exposure increased the relative membrane permeability, anthocyanin (only in cv. 3062), proline contents and the activities of peroxidases (POD) and superoxide dismutase (SOD). The only exception was the catalase activity, which was diminished in both cultivars. Root Cd contents were positively correlated with the secretion of acetic acid, oxalic acid, glutamic acid, citric acid, and succinic acid. The antioxidants like POD and SOD exhibited a positive correlation with the organic acids under Cd stress. It is likly that a high exudation of dicarboxylic organic acids improves nutrient uptake and activities of antioxidants, which enables the tolerant cultivar to acclimatize in Cd polluted environment.