Effect of the global electroneutrality condition on electromigration Taylor-Aris dispersion in a microcapillary with finite Debye layer thickness

In this work, the electromigration dispersion (EMD) due to the charged electrolytes in microchannels is considered without using the thin electrical double layer assumption. The electrokinetic flow and transport of ions are actuated within a rectangular micro-/nanochannel having a negative surface charge density under the influence of an external electric field. Due to the local variation of the conductivity and the nonvalidity of the electroneutrality condition, the local electric field varies as a function of the solute concentration, wall surface charge density, valency, and Debye layer length. The resulting electrokinetic flow due to the external electric field drives the fluid along with the charged species, where the Taylor-Aris dispersion separates the solutes into their different constituents. The local concentration dependence of the electric field leads to the formation of concentration profiles that are slightly asymmetric with respect to the standard Gaussian distribution. Including a finite Debye layer thickness has an effect on the advection of the species as well as the diffusion of the species. It is found that in cases where Debye layers are thicker, the species advects faster within the microchannel. This might give valuable insights into the nature of the EMD. Our model aims to predict the evolution of ionic concentration at all positions within the channel. A study of the higher-order statistics in skewness and kurtosis has also been conducted to obtain a better understanding of the idealized model consisting of a buffer solution.

Enhancing soil quality and yield through microbial assisted in-situ residue management in rice-rice cropping system in Odisha, Eastern India

Crop residue management has become more challenging with intensive agricultural operations. Zero tillage and crop residue returns, along with the enhancement of in-situ residue decomposition through microbial intervention, are essential measures for preserving and enhancing soil quality. To address this problem in view of stubble burning, field experiments were conducted in rice-rice (variety Swarna) cropping systems under lowland conditions, wherein the following different residue management practices were adopted viz., conventional cultivation (CC), residue incorporation (RI @ 6 t paddy straw ha-1), residue retention (RR @6 t paddy straw ha-1), and zero tillage (ZT). In this experiment, two microbial products i.e. solid microbial consortium (SMC) at 2.0 kg ha-1) and capsule (10 numbers ha-1), were evaluated in both Rabi (dry) and Kharif (wet) seasons under different residue management practices. The results on soil microbial properties showed that application of either SMC or capsule based formulation could significantly improve the soil organic carbon (SOC) content in ZT (9.51 g/kg), followed by RI (9.36 g/kg), and RR (9.34 g/kg) as compared to CC (7.61 g/kg). There were significant differences in the soil functional properties (AcP, AkP, FDA, and DHA) with microbial interventions across all residue management practices. SOC was significantly positive correlated with cellulase (R2 = 0.64, p < 0.001), β-glucosidase (R2 = 0.61, p < 0.001), and laccase (R2 = 0.66, p < 0.001) activity; however, the regression coefficients varied significantly with microbial intervention. Moreover, the availability of N, P, and K in soil was significantly (p < 0.05) improved under microbial treatments with either RR or RI practices. Among the different methods of residues management practices, RI with microbial intervention registered a consistent yield improvement (8.4-17.8%) compared to conventional practices with microbial intervention. The present findings prove that the application of decomposing microbial consortia for in-situ rice residue management under field conditions significantly enhances soil quality and crop yield compared to conventional practices.

Plastic Pandemic after COVID-19: A Global Health Concern

Abstract

COVID-19 pandemic has increased the amount of plastic burden to environment and complexities of plastic waste management. Change in behavioral pattern with advent of this pandemic led to increased practice of hygiene and increased use of different types of personal protective equipment. Unfortunately, rapid rise in production of the PPEs (like Hazmat suit, gloves, etc.) and single-use plastics used in RT-PCR and other testing are the biggest source for increased non-biodegradable plastic waste leading to amplified burden on plastic waste management. A number of measures like prioritizing the policies directed towards changes at behavioral, social and institutional level need to be started. Also, reduction in plastic waste along with proper plastic waste management policies should be implemented. To prevent the transition from one pandemic to other; improvement in government policies with public private partnership are the need of the hour.

Strigolactone GR24-mediated mitigation of phosphorus deficiency through mycorrhization in aerobic rice

Strigolactones (SLs) are a new class of plant hormones that play a significant role in regulating various aspects of plant growth promotion, stress tolerance and influence the rhizospheric microbiome. GR24 is a synthetic SL analog used in scientific research to understand the effects of SL on plants and to act as a plant growth promoter. This study aimed to conduct hormonal seed priming at different concentrations of GR24 (0.1, 0.5, 1.0, 5.0 and 10.0 µM with and without arbuscular mycorrhizal fungi (AMF) inoculation in selected aerobic rice varieties (CR Dhan 201, CR Dhan 204, CR Dhan 205, and CR Dhan 207), Kasalath-IC459373 (P-tolerant check), and IR-36 (P-susceptible check) under phosphorus (P)-deficient conditions to understand the enhancement of growth and priming effects in mycorrhization. Our findings showed that seed priming with 5.0 µM SL GR24 enhanced the performance of mycorrhization in CR Dhan 205 (88.91 %), followed by CR Dhan 204 and 207, and AMF sporulation in CR Dhan 201 (31.98 spores / 10 gm soil) and CR Dhan 207 (30.29 spores / 10 g soil), as well as rice growth. The study showed that the highly responsive variety CR Dhan 207 followed by CR Dhan 204, 205, 201, and Kasalath IC459373 showed higher P uptake than the control, and AMF treated with 5.0 µM SL GR24 varieties CR Dhan 205 followed by CR Dhan 207 and 204 showed the best performance in plant growth, chlorophyll content, and soil functional properties, such as acid and alkaline phosphatase activity, soil microbial biomass carbon (MBC), dehydrogenase activity (DHA), and fluorescein diacetate activity (FDA). Overall, AMF intervention with SL GR24 significantly increased plant growth, soil enzyme activity, and uptake of P compared to the control. Under P-deficient conditions, seed priming with 5.0 µM strigolactone GR24 and AMF inoculum significantly increased selected aerobic rice growth, P uptake, and soil enzyme activities. Application of SLs formulations with AMF inoculum in selected aerobic rice varieties, CR Dhan 207, CR Dhan 204, and CR Dhan 205, will play an important role in mycorrhization, growth, and enhancement of P utilization under P- nutrient deficient conditions.

Reducing the environmental impact of rice production in subtropical India by minimising reactive nitrogen loss

The future of reactive nitrogen (N) for subtropical lowland rice to be characterised under diverse N-management to develop adequate sustainable practices. It is a challenge to increase the efficiency of N use in lowland rice, as N can be lost in various ways, e.g., through nitrous oxide (N2O) or dinitrogen (N2) emissions, ammonia (NH3) volatilization and nitrate (NO3-) leaching. A field study was carried out in the subsequent wet (2021) and dry (2022) seasons to assess the impacts of different N management strategies on yield, N use efficiency and different N losses in a double-cropped rice system. Seven different N-management practices including application of chemical fertilisers, liquid organic fertiliser, nitrification inhibitors, organic nutrient management and integrated nutrient management (INM) were studied. The application of soil test-based neem-coated urea (NCU) during the wet season resulted in the highest economic yield, while integrated nutrient management showed the highest economic yield during the dry season. Total N losses by volatilization of NH3, N2O loss and leaching were 0.06-4.73, 0.32-2.14 and 0.25-1.93 kg ha-1, corresponding to 0.06-5.84%, 0.11-2.20% and 0.09-1.81% of total applied N, respectively. The total N-uptake in grain and straw was highest in INM (87-89% over control) followed by the soil test-based NCU (77-82% over control). In comparison, recovery efficiency of N was maximum from application of NCU + dicyandiamide during both the seasons. The N footprint of paddy rice ranged 0.46-2.01 kg N-eq. t-1 during both seasons under various N management. Ammonia volatilization was the process responsible for the largest N loss, followed by N2O emissions, and NO3- leaching in these subtropical lowland rice fields. After ranking the different N management practices on a scale of 1-7, soil test-based NCU was considered the best N management approach in the wet year 2021, while INM scored the best in the dry year 2022.

Rice-based integrated farming system improves the soil quality, bacterial community structure and system productivity under sub-humid tropical condition

Rice-based integrated farming system improves the productivity and profitability by recycling resources efficiently. In the sub-humid tropics, rice production without sufficient nutrient replenishment often leads to soil health and fertility degradation. There has been very limited research on soil health and fertility after adopting a multi-enterprising rice-based integrated farming system (IFS), notably in the rice-fish-livestock and agroforestry system, when compared to a conventional farming system (CS). Therefore, the present study analyzed the dynamics of soil properties, soil bacterial community structure and their possible interaction mechanisms, as well as their effect on regulating soil quality and production in IFS, IFSw (water stagnant area of IFS) and CS. The results indicated that soil nutrient dynamics, bacterial diversity indices (Shannon index, Simpson index, Chao 1, ACE and Fisher index) and system productivity were higher in IFSw and IFS compared to CS. Moreover, relative operational taxonomic units of dominant bacterial genera (Chloroflexi, Acidobacteria, Verrucomicrobia, Planctomycetes, Cyanobacteria, Crenarchaeota and Gemmatimonadetes) were also higher in IFSw and IFS compared to CS. Mean soil quality index (SQI) was highest in IFSw (0.780 ± 0.201) followed by IFS (0.770 ± 0.080) and CS (0.595 ± 0.244). Moreover, rice equivalent yields (REY) and rice yields were well correlated with the higher levels of soil biological indices (SQIBiol) in IFS. Overall, our results revealed that rice-based IFS improved the soil health and fertility and ensuing crop productivity through positive interaction with soil bacterial communities and nutrient stoichiometry leading to agroecosystem sustainability.

Two-component nematic superconductivity in 4Hb-TaS2

Most superconductors have an isotropic, single component order parameter and are well described by the standard (BCS) theory for superconductivity. Unconventional, multiple-component superconductors are exceptionally rare and are much less understood. Here, we combine scanning tunneling microscopy and angle-resolved macroscopic transport for studying the candidate chiral superconductor, 4Hb-TaS2. We reveal quasi-periodic one-dimensional modulations in the tunneling conductance accompanied by two-fold symmetric superconducting critical field. The strong modulation of the in-plane critical field, Hc2, points to a nematic, unconventional order parameter. However, the imaged vortex core is isotropic at low temperatures. We suggest a model that reconciles this apparent discrepancy and takes into account previously observed spontaneous time-reversal symmetry breaking at low temperatures. The model describes a competition between a dominating chiral superconducting order parameter and a nematic one. The latter emerges close to the normal phase. Our results strongly support the existence of two-component superconductivity in 4Hb-TaS2 and can provide valuable insights into other systems with coexistent charge order and superconductivity.

Unraveling the Mystery of Multi-Oocyte Follicles: An Observational Study

Introduction

Significant progress has been made in understanding oocyte fertilization and early developmental stages through in vitro fertilization (IVF) techniques. However, irregularities such as conjoined oocytes and binucleate giant oocytes, which are exceptions to the normal rule of one diploid female gamete per follicle, can potentially lead to chromosomal disorders in embryos and are recommended to be excluded from IVF attempts. The formation of primordial follicles during ovarian development, known as follicle assembly, is a critical process that establishes the ovarian follicle reserve. Multi-oocyte follicles (MOFs) containing two or more oocytes have been observed in various species, including humans, and their clinical significance on fertility and reproductive health remains unclear. Genetic and environmental factors, such as gene knockout and exposure to endocrine disruptors, have been implicated in MOF formation, but the mechanisms are not fully understood and require further investigation.

Material & Method

In this Observational study, 350 slides of ovarian tissues were scanned using an AI-based automated microscope, Grundium Ocus 20, and the TIFF images were stored in cloud storage. The slides were examined using third-party software, Pathcore Seeden Viewer, for morphometry of binovular follicles.

Results

In our observational study, we examined 350 ovarian tissue slides in detail by using an AI-based microscope, uncovering 22 slides from seven different tissues with binovular and multinovular oocytes. These rare multi-oocyte follicles (MOFs) challenge the conventional one-oocyte-per-follicle paradigm. MOFs are likely formed when oocytes fail to separate during cortical sex cord proliferation, regulated by factors several molecular factorsas well as environmental factors.

Discussion

Multiple Ovarian Follicles (MOFs) are rare phenomena where two or more oocytes exist in one follicle. They arise when oocytes fail to separate during ovarian development, which is governed by hormones such as follicle-stimulating hormone (FSH), inhibin, BMP-15, GDF-9, and GCNF. MOFs can be caused by dysregulation and exposure to chemicals such as diethylstilbestrol (DES) and isoflavones. Binovular oocytes, which occur when two oocytes are released during ovulation and are fertilised by different sperm, can result in non-identical twins, which are influenced by genetic and environmen-tal factors such as maternal age, heredity, hormonal imbalances, and assisted reproductive techniques such as in vitro fertilisation (IVF). Polynuclear oocytes with many nuclei can develop as a result of meiotic spindle defects and environmental influences. Identifying these oocyte types may aid in improving ART results by improving knowledge of the reasons of infertility and devising appropriate interventions.

Impact of long-term resource conservation techniques on biogeochemical characteristics and biological soil quality indicators in a rice green-gram farming system

Nutrient management in resource conservation practices influence the structural and functional microbial diversities and thereby affect biological processes and biochemical properties in soil. We studied the long-term effects of resource conservation technologies on functional microbial diversity and their interactions with soil biochemical properties and enzymatic activities in tropical rice-green gram cropping system. The experiment includes seven treatments viz., conventional practice (CC), brown manuring (BM), green manuring (GM), wet direct drum sowing, zero tillage, green manuring-customized leaf colour chart based-N application (GM-CLCC-N) and biochar (BC) application. The result of the present study revealed that microbial biomass nitrogen (N), carbon (C) and phosphorus (P) in GM practice were increased by 23.3, 37.7 and 35.1%, respectively than CC. GM, BM and GM-CLCC-N treatments provide higher yields than conventional practice. The average well color development value, Shannon index and McIntosh index were significantly higher by 26.6%, 86.9% and 29.2% in GM as compared to control treatment. So, from this study we can conclude that resource conservation practices like GM, GM-CLCC N and BM in combination with chemical fertilizers provide easily decomposable carbon source to support the microbial growth. Moreover, dominance of microbial activity in biomass amended treatments (GM, GM-CLCC N and BM) indicated that these treatments could supply good amount of labile C sources on real time basis for microbial growth that may protect the stable C fraction in soil, hence could support higher yield and soil organic carbon build-up in long run under rice-green gram soil.

Is predictive coding falsifiable?

Predictive-coding has justifiably become a highly influential theory in Neuroscience. However, the possibility of its unfalsifiability has been raised. We argue that if predictive-coding were unfalsifiable, it would be a problem, but there are patterns of behavioural and neuroimaging data that would stand against predictive-coding. Contra (vanilla) predictive patterns are those in which the more expected stimulus generates the largest evoked-response. However, basic formulations of predictive-coding mandate that an expected stimulus should generate little, if any, prediction error and thus little, if any, evoked-response. It has, though, been argued that contra (vanilla) predictive patterns can be obtained if precision is higher for expected stimuli. Certainly, using precision, one can increase the amplitude of an evoked-response, turning a predictive into a contra (vanilla) predictive pattern. We demonstrate that, while this is true, it does not present an absolute barrier to falsification. This is because increasing precision also reduces latency and increases the frequency of the response. These properties can be used to determine whether precision-weighting in predictive-coding justifiably explains a contra (vanilla) predictive pattern, ensuring that predictive-coding is falsifiable.

Silica sources for arsenic mitigation in rice: machine learning-based predictive modeling and risk assessment

Arsenic (As) is a well-known human carcinogen, and the consumption of rice is the main pathway for the South Asian people. The study evaluated the impact of the amendments involving CaSiO3, SiO2 nanoparticles, silica solubilizing bacteria (SSB), and rice straw compost (RSC) on mitigation of As toxicity in rice. The translocation of As from soil to cooked rice was tracked, and the results showed that RSC and its combination with SSB were the most effective in reducing As loading in rice grain by 53.2%. To determine the risk of dietary exposure to As, the average daily intake (ADI), hazard quotient (HQ), and incremental lifetime cancer risk (ILCR) were computed. The study observed that the ADI was reduced to one-third (0.24 μg kg-1bw) under RSC+SSB treatments compared to the control. An effective prediction model was established using random forest model and described the accumulation of As by rice grains depend on bioavailable As, P, and Fe which explained 48.5, 5.07%, and 2.6% of the variation in the grain As, respectively. The model anticipates that to produce As benign rice grain, soil should have P and Fe concentration more than 30 mg kg-1 and 12 mg kg-1, respectively if soil As surpasses 2.5 mg kg-1.

Marine estuaries act as better sink for greenhouse gases during winter in undisturbed mangrove than degraded ones in Sundarban, India

The estuaries provide the key pathway for travelling carbon across the land-ocean interfaces and behave as both source and sink of greenhouse gases (GHGs) in water-atmosphere systems. The sink-source characteristics of estuaries for GHGs vary spatially. The primary driving factors are adjacent ecologies (agriculture, aquaculture, etc.) and proximities to the sea. To study the sink-source characteristics of estuaries for GHGs (methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2)), the water samples were collected from 53 different locations in the estuaries for estimation of dissolved GHGs concentration and air-water GHGs exchanges. The locations represent five zones (Zone I, II, III, IV and V) based on the type and degradation status of mangroves (degraded and undisturbed), anthropogenic activities, and distance from the sea. Zone I, III, V represents to the degraded mangroves far from sea, whereas, Zone II, IV surrounded by undisturbed mangroves and nearer to sea. The average dissolved CH4 concentrations were higher in the estuaries which were adjacent to degraded mangroves (154.4 nmol L-1) than undisturbed mangroves (81.7 nmol L-1). Further, the average dissolved N2O concentrations were 48% higher in the estuaries nearer to degraded mangroves than that of undisturbed ones. Among the degraded mangrove sites, the dissolved CO2 concentrations were higher at Zone I (30.1 μmol L-1) followed by Zone III and IV, whereas in undisturbed sites, it was higher in Zone IV (22.3 μmol L-1) than Zone II (17.6 μmol L-1). Among the 53 locations, 36, 51 and 33 locations acted as a sink (negative value of exchanges) for CH4, N2O and CO2, respectively. The higher sink potential for CH4 was recorded to those estuaries adjacent to undisturbed mangroves (-791.69 μmol m-2 d-1) than the degraded ones (-23.18 μmol m-2 d-1). Similarly, the average air-water N2O and CO2 exchanges were more negative in the estuaries which were nearer to undisturbed mangroves indicating higher sink potential. The pH, and salinity of the estuary water were negatively correlated with air-water CH4 and N2O exchanges, whereas those were positively correlated with CO2 exchanges. Significantly lower dissolved GHGs and air-water GHGs exchange was observed in the estuaries adjacent to the undisturbed mangrove as compared to the degraded mangrove. The reason behind higher sink behaviours of estuaries nearer to undisturbed mangroves are higher intrusion of seawater, less nutrient availability, higher salinity, low carbon contents and alkaline pH compared to estuaries adjacent to degraded mangroves and far from sea.

Potential soil organic carbon sequestration vis-a-vis methane emission in lowland rice agroecosystem

Mitigating the atmospheric greenhouse effect while enhancing the inherent soil quality and productive capacity is possible through soil carbon (C) sequestration, which has a significant potential to counteract the adverse effects of agroecosystem level C emission through natural and anthropogenic means. Although rice is the most important food in India, feeding more than 60% of the country's population, it is commonly blamed for significant methane (CH4) emissions that accelerate climate change. Higher initial soil organic matter concentrations would create more CH4 under the flooded soil conditions, as reducible soil C is a prerequisite for CH4 generation. In India, rice is generally cultivated in lowlands under continuous flooding. Less extensive organic matter breakdown in lowland rice agroecosystems often significantly impacts the dynamics of soil active and passive C pools. Change from conventional to conservation agriculture might trap a significant quantity of SOC. The study aims to investigate the potential of rice-based soils to sequester C and reduce the accelerated greenhouse effects through modified farming practices, such as crop residue retention, crop rotation, organic farming, varietal selection, conservation agriculture, integrated nutrient management, and water management. Overall, lowland rice agroecosystems can sequester significant amounts of SOC, but this potential must be balanced against the potential for CH4 emissions. Management practices that reduce CH4 emissions while increasing soil C sequestration should be promoted and adopted to maximize the sustainability of rice agroecosystems. This review is important for understanding the effectiveness of the balance between SOC sequestration and CH4 emissions in lowland rice agroecosystems for adopting sustainable agricultural practices in the context of climate change.

Long-term impact of pulses crop rotation on soil fungal diversity in aerobic and wetland rice cultivation

Pulse crop rotation in rice cultivation is a widely accepted agronomic practice. Depending upon the water regime, rice cultivation has been classified into wetland and aerobic practices. However, no studies have been conducted so far to understand the impact of pulse crop rotation and rice mono-cropping on fungal diversity, particularly in aerobic soil. A targeted metagenomic study was conducted to compare the effects of crop rotations (rice-rice and rice-pulse) on fungal diversity in wetland and aerobic rice soils. Out of 445 OTUs, 41.80% was unknown and 58.20% were assigned to six phyla, namely Ascomycota (56.57%), Basidiomycota (1.32%), Zygomycota (0.22%), Chytridiomycota (0.04%), Glomeromycota (0.03%), and Blastocladiomycota (0.02%). Functional trait analysis found wetland rice-pulse rotation increased symbiotrophs (36.7%) and saprotrophs (62.1%) population, whereas higher pathotrophs were found in aerobic rice-rice (62.8%) and rice-pulse (61.4%) cropping system. Certain soil nutrients played a major role in shaping the fungal community; Ca had significant (p < 0.05) positive impact on saprotroph, symbiotroph and endophytes, whereas Cu had significant (p < 0.05) negative impact on pathotrophs. This study showed that rice-pulse crop rotation could enhance the saprophytic and symbiotic fungal diversity in wetland and reduce the population of pathogens in aerobic rice cultivation.

Arbuscular Mycorrhizal Fungi Response on Soil Phosphorus Utilization and Enzymes Activities in Aerobic Rice under Phosphorus-Deficient Conditions

The prominence of arbuscular mycorrhizal fungi (AMF) in sustainable rice production has long been recognized. However, there is little information about AMF response in aerobic rice cultivation under phosphorus (P)-deficient conditions. The aim of this experiment was to compare and determine the preeminent AMF effects on rice mycorrhizal colonization, responsiveness, P utilization, and different growth-promoting traits under P-deficient conditions. Different AMF genera viz. (Funneliformis sp., Rhizophagus sp., Glomus sp., Acaulospora sp., and Claroideoglomus sp.) in four different aerobic rice varieties developed by ICAR-NRRI, India (CR Dhan 201, CR Dhan 204, CR Dhan 205, and CR Dhan 207) were investigated using the check P-susceptible variety (IR 36) and the P-tolerant variety (Kasalath IC459373). Data analyzed through linear modeling approaches and bivariate associations found that AMF colonization was highly correlated with soil enzymes, particularly fluorescein diacetate (FDA) and plant P uptake. The microbial biomass carbon (MBC) and FDA content were significantly changed among rice varieties treated with AMF compared to uninoculated control. Out of four different rice varieties, CR Dhan 207 inoculated with AMF showed higher plant P uptake compared to other varieties. In all the rice varieties, AMF colonization had higher correlation coefficients with soil enzymes (FDA), MBC, and plant P uptake than uninoculated control. The present study indicates that AMF intervention in aerobic rice cultivation under P-deficient conditions significantly increased plant P uptake, soil enzymes activities and plant growth promotion. Thus, the information gathered from this study will help us to develop a viable AMF package for sustainable aerobic rice cultivation.

Fluoride risk assessment from agricultural soils in India: a study based on vertical, spatial and geochemical distribution

Fluoride (F) in agricultural soil is increasing continuously due to injudicious application of F-laden fertilizers, causing global concern about fluorosis disease. The objective of the study was to assess F risk in humans due to soil ingestion, dermal contact, and particulate inhalation during various agricultural activities. The study also emphasized chemical fractionation, distribution, and geochemical understanding of high F incidence. Agricultural surface soil was sampled randomly from 5 km × 5 km square grids besides soil profile samples for studying the vertical distribution of F. Various F fractions in soil (1:1 soil:water ratio, calcium chloride extractable F, hot water soluble F, exchangeable F, Fe-Mn oxide bound F, organic matter bound F, residual F, and total F) were estimated using the sequential fractionation method. Multivariate geochemical analysis and soil F risk were also assessed in humans. The water soluble F (F_1:1) and CaCl₂ extractable F (F_Ca) varied between 0.11 to 6.73 mg kg^-1 and 1.02 to 6.94 mg F kg^-1 soil, respectively. Total fluoride (TF) however, ranged between 115 to 456 mg F kg^-1. A higher average of F_Ca/TF moving down the soil profile indicated a propensity for F endemicity. Weathering, ion-exchange, alkalinity, and clay were found to control the soil geochemistry of the area. The F contamination index explained > 82% variance of F contamination, but the hazard quotient of F for an adult was found < 1, indicating no potential fluorosis risk in the area. This study is the first of its kind in India, where ecological risk due to F from agricultural soil was assessed in humans and will be a benchmark for future researchers.

Biosynthesis and characterization of nanoparticles, its advantages, various aspects and risk assessment to maintain the sustainable agriculture: Emerging technology in modern era science

The current review aims to gain knowledge on the biosynthesis and characterization of nanoparticles (NPs), their multifactorial role, and emerging trends of NPs utilization in modern science, particularly in sustainable agriculture, for increased yield to solve the food problem in the coming era. However, it is well known that an environment-friendly resource is in excessive demand, and green chemistry is an advanced and rising resource in exploring eco-friendly processes. Plant extracts or other resources can be utilized to synthesize different types of NPS. Hence NPs can be synthesized by organic or inorganic molecules. Inorganic molecules are hydrophilic, biocompatible, and highly steady compared to organic types. NPs occur in numerous chemical conformations ranging from amphiphilic molecules to metal oxides, from artificial polymers to bulky biomolecules. NPs structures can be examined by different approaches, i.e., Raman spectroscopy, optical spectroscopy, X-ray fluorescence, and solid-state NMR. Nano-agrochemical is a unification of nanotechnology and agro-chemicals, which has brought about the manufacture of nano-fertilizers, nano-pesticides, nano-herbicides, nano-insecticides, and nano-fungicides. NPs can also be utilized as an antimicrobial solution, but the mode of action for antibacterial NPs is poorly understood. Presently known mechanisms comprise the induction of oxidative stress, the release of metal ions, and non-oxidative stress. Multiple modes of action towards microbes would be needed in a similar bacterial cell for antibacterial resistance to develop. Finally, we visualize multidisciplinary cooperative methods will be essential to fill the information gap in nano-agrochemicals and drive toward the usage of green NPs in agriculture and plant science study.

A state-of-the-art review on cadmium uptake, toxicity, and tolerance in rice: From physiological response to remediation process

Cadmium (Cd), a major contaminant of concern, has been extensively reviewed and debated for its anthropogenic global shifts. Cadmium levels in rice grains raise wide food safety concerns. The aim of this review is therefore to capture the dynamics of Cd in paddy soil, translocation pathways of Cd from soil to consumption rice, and assess its bio-accessibility in human consumption. In crop plants, Cd reduces absorption of nutrients and water, triggers oxidative stress, and inhibits plant metabolism. Understanding the mechanisms and behaviour of Cd in paddy soil and rice allows to explain, predict and intervene in Cd transferability from soil to grains and human exposure. Factors affecting Cd movement in soil, and further to rice grain, are elucidated. Recently, physiological and molecular understanding of Cd transport in rice plants have been advanced. Morphological-biochemical characteristics and Cd transporters of plants in such a movement were also highlighted. Ecologically viable remediation approaches, including low input cost agronomic methods, phytoremediation and microbial bioremediation methods, are emerging.

Drought hotspot maps and regional drought characteristics curves: Development of a novel framework and its application to an Indian River basin undergoing climatic changes

Drought is one of the significant natural disasters that incurs billion dollars of economic damage every year. Among all, agricultural drought needs critical attention for drought monitoring due to its direct effect on crop yield and management of irrigation water. Most of the previous studies focused on regionalizing drought using k-means, hierarchal, fuzzy, and entropy-based clustering techniques. However, these techniques are not suitable where the clusters are not separated distinctively, and the number of clusters cannot be estimated automatically. In this study, we have developed agricultural drought hotspot maps using Soil moisture deficit index (SMDI) and the regional severity (S), duration (D), and frequency (F) curves using complex network algorithm for the future warming climate (2041-2070) of the Mahanadi River basin (MRB) in India. We have used a modified dynamic Budyko (DB) hydrological model to simulate daily soil moisture at a spatial scale of 0.25° × 0.25° using input from four GCMs for the RCP 4.5 scenario. The modified DB model was calibrated and validated for the study area. The model proved to be capable of simulating the soil moisture dynamics over the basin and also effectively captured the historical droughts occurred in the basin. The drought hotspot maps of the basin suggest that the northern, south-eastern, and central parts of the basins are going to experience more number of droughts. The results suggest that for most of the clusters, the regional S-D-F curve can be utilized to understand the future drought characteristics at site-specific as well as regional scale, as the confidence band is found to be very narrow. Overall, our study provides a framework to develop regional S-D-F curve.

Lytic polysaccharide monooxygenases (LPMOs) producing microbes: A novel approach for rapid recycling of agricultural wastes

Out of the huge quantity of agricultural wastes produced globally, rice straw is one of the most abundant ligno-cellulosic waste. For efficient utilization of these wastes, several cost-effective biological processes are available. The practice of field level in-situ or ex-situ decomposition of rice straw is having less degree of adoption due to its poor decomposition ability within a short time span between rice harvest and sowing of the next crop. Agricultural wastes including rice straw are in general utilized by using lignocellulose degrading microbes for industrial metabolite or compost production. However, bioconversion of crystalline cellulose and lignin present in the waste, into simple molecules is a challenging task. To resolve this issue, researchers have identified a novel new generation microbial enzyme i.e., lytic polysaccharide monooxygenases (LPMOs) and reported that the combination of LPMOs with other glycolytic enzymes are found efficient. This review explains the progress made in LPMOs and their role in lignocellulose bioconversion and the possibility of exploring LPMOs producers for rapid decomposition of agricultural wastes. Also, it provides insights to identify the knowledge gaps in improving the potential of the existing ligno-cellulolytic microbial consortium for efficient utilization of agricultural wastes at industrial and field levels.

New generation post-emergence herbicides and their impact on arbuscular mycorrhizae fungal association in rice

To prevent weed invasion in direct seeded rice cultivation, several new generation post emergence herbicides viz. bispyribac sodium, flucetosulfuron, ethoxysulfuron, fenoxaprop-p ethyl, penoxsulam, fenoxaprop-p-ethyl plus ethoxysulfuron and cyhalofop‑butyl plus penoxsulam are widely used in sub-tropical rice ecosystems of Eastern India. The main objective of this study was to know whether application of above listed post emergence herbicides at recommended (n1) and double recommended dose (n2) has any negative impact on arbuscular mycorrhizal fungal (AMF) association in rice plants. Further, the effects of herbicides on soil microbial properties viz. microbial biomass carbon (MBC), fluroscein diacetate (FDA), dehydrogenase (DHA), acid phosphatase (AcP) and alkaline phosphatase (AkP) activities were analyzed using unsupervised and supervised learning methods. Results indicated that among different herbicides evaluated only application of penoxsulam significantly (p<0.05) reduced the AMF root colonization (58.0%) at recommended dose (n1) compared to only AMF (70.3%) application. Whereas, application of bispyribac sodium (both n1 and n2 dose) enhanced AMF sporulation (1100 spores/100 g) and root colonization (86.68%) compared to other herbicides application. Unsupervised learning approaches through PCA found that application of bispyribac sodium enhanced both above ground plant growth responses and soil microbial properties, but penoxsulam had negative impact. But, the combined application of penoxsulam and cyhalofop‑butyl did not show any negative impact on AMF association in rice plants. This study concluded that selection of right type of post-emergence herbicides are very important to minimize the harmful effect or enhance AMF association in rice plants.

Understanding rice growth-promoting potential of Enterobacter spp. isolated from long-term organic farming soil in India through a supervised learning approach

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Diazotrophic bacteria were screened and characterized from long-term organic rice fields of Sikkim

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Screened the diazotrophic bacteria for nitrogen fixing ability and plant growth promoting traits

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Enterobacter was commonly found in paddy soils of Sikkim

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Enterobacter species were significantly enhanced the above and below ground responses in rice plants

This study addresses the plant beneficial enterobacteria present in rice rhizosphere and their efficiency for enhancing nitrogen uptake in rice plant. Using culturable approaches, the population of total diazotrophs present in rhizosphere samples collected from different organic rice fields of Sikkim were studied and recorded in the range between 4.62 to 4.97 log₁₀ CFU/g soil. All the isolated commonly occurred diazotrophic bacterial isolates were screened based on their ability to fix nitrogen in milligram per gram of sugar consumed under in-vitro condition with the reference check. In addition to nitrogen fixation, plant growth promoting traits such as production of indole-3-acetic acid and gibberellic acid were estimated using spectrophotometric approaches and compared against Bacillus subtilis as reference multi-potent plant growth promoting strain. In-vivo evaluation of these diazotrophic species in rice found improvement in both above and below ground responses in rice plant evaluated by estimating changes in chlorophyll concentration, plant biomass, root architecture, nitrogen uptake, microbial biomass and associated biochemical activity of soil. Further, the selected isolates were identified through DNA targeted analysis of 16S rRNA gene present in diazotrophs and which identified that the isolates belonged to the Enterobacter genus. Statistical models were prepared for deciphering the dynamics of plant growth improvement due to selective enrichment of rhizosphere bacteria and found significant (p<0.05) correlation between soil and plant parameters. This study concludes that Enterobacter spp. present in organic paddy soils of Sikkim having good nitrogen fixing abilities and whose selective enrichment in rhizosphere improved nitrogen uptake and plant growth promotion in rice plant.

Anomalous magnetoresistance and magneto-thermal properties of the half-Heuslers,RPdSi (RY, Gd-Er)

Here, we present a detailed study on the magnetic, magneto-transport, and magneto-thermal properties of the equiatomic half-Heusler compounds with the general formula,RPdSi (R= Y and rare-earth, Gd-Er). These materials crystallize in two different superstructures of the TiNiSi-type orthorhombic unit cell with the space groupsPnmaandPmmn. Our magnetic and heat capacity measurements reveal the onset of an antiferromagnetic (AFM) ordering in the temperature range 3-16 K for all the local moments bearingRPdSi compounds, while the non-magnetic analog, YPdSi exhibits a Pauli-paramagnetic behaviour. The AFM state of these compounds can be tuned by magnetic field and temperature as demonstrated by the magnetic measurements below the Neel temperature (T_N). Most importantly, this tuning of the magnetic structure is well documented in the complex temperature and field dependence of magnetoresistance (MR) and magnetocaloric effect (MCE). Our study establishes a striking correlation of the commensurate/incommensurate AFM structure with that of positive/negative MR and MCE in this series of compounds. We emphasize that such a framework applies to a large number of AFM intermetallic systems.

Trait variations and expression profiling of OsPHT1 gene family at the early growth-stages under phosphorus-limited conditions

To better understand the early response of genotypes to limited-phosphorus (P) conditions and the role of the phosphate transporter OsPHT1 gene family in the presence of PSTOL1, it is essential to characterize the level of tolerance in rice under limited-P conditions. In the present experiment, six rice genotypes were studied in three-way interactions [genotype (G) × phosphorus (P) × duration (D)] by comparing them at two instances (14 d and 28 d) under seven different concentrations of P (0.5‒10.0 ppm) in a hydroponic system. Trait differences and interactions of these traits were clearly distinguished among the various P rates. However, aboveground trait expression registered increased growth from 6.0 to 10.0 ppm of P. The major root-attributed traits in 0.5 ppm of P are significantly increased vis-à-vis 10 ppm of P. Analysis of variance displayed a significant difference between the genotypes for PSTOL1 and PHT1 expression. In low P, maximum root length with a shoot and root dry weight was observed in a new indigenous accession, IC459373, with higher expression of PSTOL1 than in Dular and IR64-Pup1 in 0.5 ppm of P at 14 d. Among the 13 PHT1 genes, OsPT1, OsPT2, OsPT6, and OsPT13 showed significant upregulation in IC459373, Dular, and IR64-Pup1. These results indicated that studying the expression levels of the PSTOL1 and PHT1 gene family at the early growth stages would be helpful in identifying superior donors to improve low-P tolerance and P-use efficiency in rice breeding programs.

Combined application of ascorbic acid and endophytic N-fixing Azotobacter chroococcum Avi2 modulates photosynthetic efficacy, antioxidants and growth-promotion in rice under moisture deficit stress

This group has previously reported the role of ascorbic acid (AA) as an antioxidant for survivability and ability to enhancing diazotrophic efficacy in Azotobacter chroococcum Avi2 under hydrogen peroxide (H₂O₂) stress. However, the present study showed the combined application of AA and Avi2 in drought-susceptible (IR64 and Naveen) and drought-tolerant (Ankit and Satyabhama) rice cultivars to determine their photosynthetic efficacy (chlorophyll fluorescence-imaging), antioxidants, and plant growth-promotion (PGP) under moisture deficit stress (MS, -60 kPa). The results indicated that combined application of AA and Avi2 significantly (p < 0.05) increased the total chlorophyll, relative water content, electrolytic leakage, super oxide dismutase, and catalase activities in all rice cultivars as compared to other MS treatments, whereas stress indicators like proline and H₂O₂ contents were proportionally increased under MS and their concentration were normalized under combined application of AA and Avi2. Photochemical quenching, non-photochemical quenching, photosynthetic electron transport rate, and the effective quantum efficiency were found to be increased significantly (p < 0.05) in Avi2 + AA as compared to other MS treatments. Moreover, rice roots harbored significantly (p < 0.05) higher copy number of nifH gene in Avi2 + AA treatment followed by Avi2 compared to flooded control and other MS treatments. Combined application of AA and Avi2 also increased the grain yield significantly (p < 0.05) by 7.09 % and 3.92 % in drought-tolerant (Ankit and Satyabhama, respectively) and 31.70 % and 34.19 % in drought-susceptible (IR64 and Naveen, respectively) rice cultivars compared to MS treatment. Overall, the present study indicated that AA along with Avi2 could be an effective formulation to alleviate MS vis à vis enhances PGP traits in rice.

Alteration in plant spacing improves submergence tolerance in Sub1 and non-Sub1 rice (cv. IR64) by better light interception and effective carbohydrate utilisation under stress

Besides genetic improvement for developing stress-tolerant cultivars, agronomic management may also add considerable tolerance against different abiotic stresses in crop plants. In the present study, we evaluated the effect of six different spacing treatments (S1: 10 × 10 cm; S2: 15 × 10 cm; S3:15 × 15 cm; S4:20 × 10 cm; S5: 20 × 15 cm; S6: 20 × 20 cm (row-row × plant-plant)) for improving submergence tolerance in rice. A high yielding submergence intolerant rice cultivar IR64 was tested against its SUB1 QTL introgressed counterpart (IR64-Sub1) for 12 days of complete submergence for different spacing treatments in field tanks. Relatively wider spaced plants showed higher individual plant biomass and early seedling vigour, which was particularly helpful for IR64 in increasing plant survival (by 150% in S6 over S1) under 12 days of submergence, whereas the improvement was less in IR64-Sub1 (13%). Underwater radiation inside the plant canopy, particularly beyond 40 cm water depth, was significantly greater in wider spacing treatments. Leaf senescence pattern captured by SPAD chlorophyll meter reading and chlorophyll fluorescence imaging data (Fm, Fv/Fm) taken at different time intervals after stress imposition suggested that there was lesser light penetration inside the canopy of closer spaced plants, and that it might hasten leaf senescence and damage to the photosynthetic system. The initial content of total non-structural carbohydrate (NSC) was higher in wider spaced plants of IR64, and also the rate of depletion of NSC was lesser compared with closer spaced plants. In contrast, there was not much difference in NSC depletion rate under different spacing in IR64-Sub1. Further, higher antioxidant enzyme activities in wider spaced plants (both IR64 and IR64-Sub1) after de-submergence indicated better stress recovery and improved tolerance. Taken together we found that wider spacing (row-row: 20 cm and plant-plant: 15 cm and more) can significantly improve submergence tolerance ability in rice, particularly in submergence intolerant non-Sub1 cultivar like IR64, perhaps due to better underwater light penetration, delayed leaf senescence and slower depletion of NSC reserve.

Health risks from trace elements in muscles of some commonly available fish in Australia and India

The levels of trace elements (As, Hg, Cr, Cd, Pb, Co, Ni, Cu, Mn and Zn) in commercially important fish species sampled from fish markets of Adelaide, Australia; canned fish from South Australian supermarkets; and fish markets of West Bengal, India were determined by inductively coupled plasma mass spectrometry (ICP-MS) after microwave digestion. Mercury was determined by using triple quadrupole ICP-MS. The accuracy of the methods was assessed with a certified standard reference material (NRCC-DORM-3 dogfish protein), and the results were compared with values reported in the literature. The results indicated considerable variations in the accumulation of trace elements among the fish species. The relationship between species with respect to trace element concentrations was examined using cluster analysis, which showed Indian fish species forming distinct groups from the others. Other than As in sardines, whiting and snapper and Hg in swordfish and snapper, the trace element concentrations were within permissible limits recommended by various standards. Based on the estimated daily intake (EDI), fish samples analysed in this study can be considered safe for human consumption as per the recommended daily dietary allowance limit fixed by various agencies. Continuous monitoring and assessments of fish metal(loid) content are needed to generate more data and safeguard human health.

Non-target effect of bispyribac sodium on soil microbial community in paddy soil

Bispyribac sodium is frequently used herbicide in the rice field. Though, it has been targeted to kill rice weeds, but its non-target effect on soil microbes in paddy soil was largely unknown. Therefore, in the present study, an attempt was made to assess the non-target effect of bispyribac sodium on alteration of functional variation of soil microbial community and their correlation with microbial biomass carbon (MBC) and soil enzymes. A microcosm experiment set up was made comprising three treatments viz., control (CON) (without application of bispyribac sodium), recommended dose of bispyribac sodium (35 g ha^-1) (BS), and double the dose of BS (70 g ha^-1) (DBS). Results indicated that the MBC and soil enzyme activities (dehydrogenase, alkaline phosphatase and urease) in BS and DBS-treated soil were significantly (p < 0.05) declined from 1^st to 30^th day after application as compared to CON. Counts of heterotrophic bacteria, actinomycetes and fungal population were also decreased in BS and DBS-treated soil. The average well color development (AWCD) values derived from Biolog®ecoplates followed the order of DBS ˂ BS ˂ CON. Shannon index value was high (p ≤ 0.05) in CON compared to soil-treated with BS and DBS. Principal component analysis (PCA) showed a clear distinction of the cluster of treatments between CON, BS and DBS. Biplot analysis and heatmap suggested that carboxylic compounds and amino acids showed positive response towards BS-treated soil, whereas phenolic compounds had positive correlation with DBS-treated soil. PCA analysis indicated that oligotrophs was rich in BS-treated paddy soil, whereas copiotrophs and asymbiotic nitrogen fixers were richer in DBS treatment. Overall, the present study revealed that application of recommended dose of BS and its double dose alter the soil microbial population, enzyme activities and functional microbial diversity in paddy soil.

Metal(loid)s (As, Hg, Se, Pb and Cd) in paddy soil: Bioavailability and potential risk to human health

Rice is one of the principal staple foods, essential for safeguarding the global food and nutritional security, but due to different natural and anthropogenic sources, it also acts as one of the biggest reservoirs of potentially toxic metal(loids) like As, Hg, Se, Pb and Cd. This review summarizes mobilization, translocation and speciation mechanism of these metal(loids) in soil-plant continuum as well as available cost-effective remediation measures and future research needs to eliminate the long-term risk to human health. High concentrations of these elements not only cause toxicity problems in plants, but also in animals that consume them and gradual deposition of these elements leads to the risk of bioaccumulation. The extensive occurrence of contaminated rice grains globally poses substantial public health risk and merits immediate action. People living in hotspots of contamination are exposed to higher health risks, however, rice import/export among different countries make the problem of global concern. Accumulation of As, Hg, Se, Pb and Cd in rice grains can be reduced by reducing their bioavailability, and controlling their uptake by rice plants. The contaminated soils can be reclaimed by phytoremediation, bioremediation, chemical amendments and mechanical measures; however these methods are either too expensive and/or too slow. Integration of innovative agronomic practices like crop establishment methods and improved irrigation and nutrient management practices are important steps to help mitigate the accumulation in soil as well as plant parts. Adoption of transgenic techniques for development of rice cultivars with low accumulation in edible plant parts could be a realistic option that would permit rice cultivation in soils with high bioavailability of these metal(loid)s.

Understanding interaction effect of arbuscular mycorrhizal fungi in rice under elevated carbon dioxide conditions

Arbuscular mycorrhizal fungi (AMF), particularly the Glomerales group, play a paramount role in plant nutrient uptake, and abiotic and biotic stress management in rice, but recent evidence revealed that elevated CO₂ concentration considerably reduces the Glomerales group in soil. In view of this, the present study was initiated to understand the interaction effect of native Glomerales species application in rice plants (cv. Naveen) under elevated CO₂ concentrations (400 ± 10, 550 ± 20, and 700 ± 20 ppm) in open-top chambers. Three different modes of application of the AMF inoculum were evaluated, of which, combined application of AMF at the seedling production and transplanting stages showed increased AMF colonization, which significantly improved grain yield by 25.08% and also increased uptake of phosphorus by 18.2% and nitrogen by 49.5%, as observed at 700-ppm CO₂ concentration. Organic acids secretion in rice root increased in AMF-inoculated plants exposed to 700-ppm CO₂ concentration. To understand the overall effect of CO₂ elevation on AMF interaction with the rice plant, principal component and partial least square regression analysis were performed, which found both positive and negative responses under elevated CO₂ concentration.

Structural diversity and efficacy of culturable cellulose decomposing bacteria isolated from rice-pulse resource conservation practices

The diversity of cellulolytic bacteria from the rice-pulse system can be sourced for identification of efficient cellulose decomposing microbial strains. In the present study, the abundance, structural diversity, and cellulolytic potential of the culturable bacterial community were studied in 5-year old rice-pulse system under different resource conservation technologies. Higher cellulose (68% more) and xylanase (35% more) activities were observed under zero tilled soil. The populations of cellulolytic bacteria were significantly higher (44%) in zero tillage (ZT) treatment than those of conventional practice. Results revealed that the cellulolytic bacterial diversity was found to be significantly higher under ZT practice, but the present population may not be sufficient for effective recycling of organic wastes in this system. Out of 290 bacterial isolates, 20 isolates had significantly higher cellulolytic activities, of which the top three superior isolates were received from ZT practice. The cellulolytic bacterial diversity based on 16S rDNA sequencing data revealed that the Firmicutes was the most dominant phyla and the Bacillus spp. were the common genus, the observation also showed that there were 17 different haplotypes were recorded among 20 isolates of cellulolytic bacteria. The present findings indicated that long-term ZT in the rice-pulse system could be a unique source for efficient cellulose decomposing bacteria and further the efficient bacterial strains isolated from this system can be used as efficient bioinoculants for in situ as well as ex-situ decomposition of rice straw particularly in conservation agriculture.

Water vapor flux in tropical lowland rice

A field experiment was conducted at Indian Council of Agricultural Research-National Rice Research Institute, Cuttack, Odisha, India in the dry seasons of 2015 and 2016 to assess the water vapor flux (FH₂O) and its relationship with other climatic variables. The FH₂O and climatic variables were measured by an eddy covariance system and a micrometeorological observatory. Daily mean FH₂O during the dry seasons of 2015 and 2016 were 0.009-0.092 g m^-2 s^-1 and 0.014-0.101 g m^-2 s^-1, respectively. Seasonal average FH₂O was 14.6% higher in 2016 than that in 2015. Diurnal variation for FH₂O showed a bell-shaped curve with its peak at 13:30-14:00 Indian Standard Time (IST) in both the years. Carbon dioxide flux was found higher with rise in FH₂O. This relationship was stronger at higher vapor pressure deficit (VPD) (20 ≤ VPD ≤ 40 and VPD > 40 hPa). The FH₂O showed significant positive correlation with latent heat flux, net radiation flux, photosynthatically active radiation, air, water and soil temperatures, shortwave down and upwell radiations, maximum and minimum temperatures, evaporation, and relative humidity in both the years. Principal component analysis showed that FH₂O was very close to latent heat flux in both the years (Pearson correlation coefficient close to 1). The two-dimensional observation map of the principal component F1 and F2 showed the observations taken during the vegetative stage and panicle initiation stage, and flowering stage and maturity stage were closer to each other. It can be concluded that the most important climatic variables controlling the FH₂O were latent heat of vaporization, net radiation, air temperature, soil temperatures, and water temperature.

Ascorbic acid formulation for survivability and diazotrophic efficacy of Azotobacter chroococcum Avi2 (MCC 3432) under hydrogen peroxide stress and its role in plant-growth promotion in rice (Oryza sativa L.)

Oxidative stress generates reactive oxygen species which causes cell damage of living organisms and are normally detoxified by antioxidants. Indirect reports signify the damages caused by reactive oxygen species and neutralized by antioxidant, but the direct evidence to confirm this hypothesis is still unclear. To validate our hypothesis, an attempt was made in a diazotrophic bacterium (Azotobacter chroococcum Avi2) as a biological system, and hydrogen peroxide (H₂O₂) and ascorbic acid were used as oxidative stress and antioxidant supplement, respectively. Additionally, rice plant-growth attributes by Avi2 was also assessed under H₂O₂ and ascorbic acid. Results indicated that higher concentration of H₂O₂ (2.5 mM-4.5 mM) showed the complete mortality of Avi2, whereas one ppm ascorbic acid neutralized the effect of H₂O₂. Turbidity, colony forming unit, DNA quantity, nifH gene abundance, indole acetic acid and ammonia productions were significantly (p < 0.5) increased by 11.93%, 17.29%, 19.80%, 74.77%, 71.89%, and 42.53%, respectively in Avi2-treated with 1.5 mM H₂O₂ plus ascorbic acid compared to 1.5 mM H₂O₂ alone. Superoxide dismutase was significantly (p < 0.5) increased by 60.85%, whereas catalase and ascorbate peroxidase activities were significantly (p < 0.05) decreased by 64.28% and 68.88% in Avi2-treated with 1.5 mM H₂O₂ plus ascorbic acid compared to 1.5 mM H₂O₂ alone. Germination percentage of three rice cultivars (FR13a, Naveen and Sahbhagi dhan) were significantly (p < 0.5) increased by 20%, 13.33%, and 4%, respectively in Avi2-treated with 0.6 mM H₂O₂ plus ascorbic acid compared with uninoculated control. Overall, this study indicated that ascorbic acid formulation neutralizes the H₂O₂-oxidative stress and enhances the survivability and plant growth-promoting efficacy of A. chroococcum Avi2 and therefore, it may be used as an effective formulation of bio-inoculants in rice under oxidative stress.

Current and emerging methodologies for estimating carbon sequestration in agricultural soils: A review

This review covers the current and emerging analytical methods used in laboratory, field, landscape and regional contexts for measuring soil organic carbon (SOC) sequestration in agricultural soil. Soil depth plays an important role in estimating SOC sequestration. Selecting appropriate sampling design, depth of soil, use of proper analytical methods and base line selection are prerequisites for estimating accurately the soil carbon stocks. Traditional methods of wet digestion and dry combustion (DC) are extensively used for routine laboratory analysis; the latter is considered to be the "gold standard" and superior to the former for routine laboratory analysis. Recent spectroscopic techniques can measure SOC stocks in laboratory and in-situ even up to a deeper depth. Aerial spectroscopy using multispectral and/or hyperspectral sensors located on aircraft, unmanned aerial vehicles (UAVs) or satellite platforms can measure surface soil organic carbon. Although these techniques' current precision is low, the next generation hyperspectral sensor with improved signal noise ratio will further improve the accuracy of prediction. At the ecosystem level, carbon balance can be estimated directly using the eddy-covariance approach and indirectly by employing agricultural life cycle analysis (LCA). These methods have tremendous potential for estimating SOC. Irrespective of old or new approaches, depending on the resources and research needed, they occupy a unique place in soil carbon and climate research. This paper highlights the overview, potential limitations of various scale-dependent techniques for measuring SOC sequestration in agricultural soil.

Practical techniques to homogenize the feed gas mixture and enhance the laser-jet interaction time in laser assisted aerodynamic separation studies

Laser assisted aerodynamic separation not only suffers from lengthy homogenization time of the feed gas mixture but also dilution of the enriched stream when the duration of the pulsed gas jet stream far exceeds that of the emission of the pulsed laser. We report here practical techniques to overcome the former and alleviate the latter by imposing forced circulation of the feed gas prior to affecting aerodynamic separation and the rim gas during the separation process, respectively. The forced circulation of the feed gas comprising the process gas and the buffer gas resulted in drastic reduction in the time required for their thorough mixing. The recirculation of the rim gas, on the other hand, back to the pulsed nozzle through the feed vessel allowed its increased interaction with the laser beam, thereby reducing the dilution of enrichment to a certain extent.

Inter-relationship between intercepted radiation and rice yield influenced by transplanting time, method, and variety

Photosynthetically active radiation (PAR) is one of the most important environmental factors that determine the productivity and grain quality of the crops. Continuous rainy days or cloudy weather throughout crop growth especially at critical stages often resulted in great loss of grain quality and yield in rice. Low light stress has rigorously constrained the rice production in various rice-growing regions, especially in Southeast Asia. Method and time of planting are the major management factors contributing to the higher yield potential of rice by influencing light harvesting and use efficiency. Present study was executed consecutively for 5 years (kharif seasons of 2012-2016) to determine whether planting time improves the radiation absorption and use efficiency in different duration rice cultivars. We evaluated the difference in plant growth and development leading to yield formation under different planting time which related to radiation incidence and interception. The results of the study revealed that PAR interception depends on morphological characters of cultivars and also with agronomic management such as transplanting time and method. Long duration cultivar intercepted more PAR but interception decreased due to late planting (3rd week of July), whereas short duration cultivars (Naveen) when planted earlier (1st week of June) could not effectively utilize intercepted PAR constraining the biomass accumulation and yield formation. Effect of planting density and crop architecture on PAR absorption was apparent among establishment methods as light interception at crop canopy was highest in the system of rice intensification and lowest in that of wet direct seeding. In general, Pooja as a long duration cultivar intercepted more PAR per day but when compared on same date of planting, the comparative absorption of radiation was 30.6% higher in Naveen. The lower yields in the wet season are attributed mostly to reduction in grain number per panicle or per unit land area, which is a consequence of high spikelet sterility. Grain yield of rice planted in July third week was reduced by 3.8, 12.3, and 6.9% over June first and third week and July first week, respectively, mainly due to spikelet sterility (26%) and lower grains per panicle (18%). Our results indicated that agronomic management like optimum time of sowing, cultivar duration, and establishment methods should be followed for yield improvement in tropical lowlands where light intensity is limiting due to prevailing weather situations.

Effects of water deficit stress on agronomic and physiological responses of rice and greenhouse gas emission from rice soil under elevated atmospheric CO2

Rice is the foremost staple food in the world, safeguarding the global food and nutritional security. Rise in atmospheric carbon dioxide (CO₂) and water deficits are threatening global rice productivity and sustainability. Under real field conditions these climatic factors often interact with each other resulting in impacts that are remarkably different compared to individual factor exposure. Rice soils exposed to drought and elevated CO₂ (eCO₂) alters the biomass, diversity and activity of soil microorganisms affecting greenhouse gas (GHG) emission dynamics. In this review we have discussed the impacts of eCO₂ and water deficit on agronomic, biochemical and physiological responses of rice and GHGs emissions from rice soils. Drought usually results in oxidative stress due to stomatal closure, dry weight reduction, formation of reactive oxygen species, decrease in relative water content and increase in electrolyte leakage at almost all growth and developmental phases of rice. Elevated atmospheric CO₂ concentration reduces the negative effects of drought by improving plant water relations, reducing stomatal opening, decreasing transpiration, increasing canopy photosynthesis, shortening crop growth period and increasing the antioxidant metabolite activities in rice. Increased scientific understanding of the effects of drought and eCO₂ on rice agronomy, physiology and GHG emission dynamics of rice soil is essential for devising adaptation options. Integration of novel agronomic practices viz., crop establishment methods and alternate cropping systems with improved water and nutrient management are important steps to help rice farmers cope with drought and eCO₂. The review summarizes future research needs for ensuring sustained global food security under future warmer, drier and high CO₂ conditions.

Ecosystem services in different agro-climatic zones in eastern India: impact of land use and land cover change

Land use and land cover (LULC) change have considerable influence on ecosystem services. Assessing change in ecosystem services due to LULC change at different spatial and temporal scales will help to identify suitable management practices for sustaining ecosystem productivity and maintaining the ecological balance. The objective of this study was to investigate variations in ecosystem services in response to LULC change over 27 years in four agro-climatic zones (ACZ) of eastern India using satellite imagery for the year 1989, 1996, 2005, 2011 (Landsat TM) and 2016 (Landsat 8 OLI). The satellite images were classified into six LULC classes, agriculture land, forest, waterbody, wasteland, built-up, and mining area. During the study period (1989 to 2016), forest cover reduced by 5.2%, 13.7%, and 3.6% in Sambalpur, Keonjhar, and Kandhamal districts of Odisha, respectively. In Balasore, agricultural land reduced by 17.2% due to its conversion to built-up land. The value of ecosystem services per unit area followed the order of waterbodies > agricultural land > forests. A different set of indicators, e.g., by explicitly including diversity, could change the rank between these land uses, so the temporal trends within a land use are more important than the absolute values. Total ecosystem services increased by US$ 1296.4 × 10⁵ (50.74%), US$ 1100.7 × 10⁵ (98.52%), US$ 1867 × 10⁵ (61.64%), and US$ 1242.6 × 10⁵ (46.13%) for Sambalpur, Balasore, Kandhamal, and Keonjhar, respectively.

Novel screening protocol for precise phenotyping of salt-tolerance at reproductive stage in rice

The present study reports an unequivocal and improved protocol for efficient screening of salt tolerance at flowering stage in rice, which can aid phenotyping of population for subsequent identification of QTLs associated with salinity stress, particularly at reproductive stage. To validate the new method, the selection criteria, level and time of imposition of stress; plant growth medium were standardized using three rice genotypes. The setup was established with a piezometer placed in a perforated pot for continuous monitoring of soil EC and pH throughout the period of study. Further, fertilizer enriched soil was partially substituted by gravels for stabilization and maintaining the uniformity of soil EC in pots without hindering its buffering capacity. The protocol including modified medium (Soil:Stone, 4:1) at 8 dS m^-1 salinity level was validated using seven different genotypes possessing differential salt sensitivity. Based on the important selection traits such as high stability index for plant yield, harvest index and number of grains/panicle and also high K⁺ concentration and low Na⁺- K⁺ ratio in flag leaf at grain filling stage were validated and employed in the evaluation of a mapping population in the modified screening medium. The method was found significantly efficient for easy maintenance of desired level of soil salinity and identification of genotypes tolerant to salinity at reproductive stage.

Boron application improves yield of rice cultivars under high temperature stress during vegetative and reproductive stages

It is reported that high temperatures (HT) would cause a marked decrease in world rice production. In tropical regions, high temperatures are a constraint to rice production and the most damaging effect is on spikelet sterility. Boron (B) plays a very important role in the cell wall formation, sugar translocation, and reproduction of the rice crop and could play an important role in alleviating high temperature stress. A pot culture experiment was conducted to study the effect of B application on high temperature tolerance of rice cultivars in B-deficient soil. The treatments comprised of four boron application treatments viz. control (B0), soil application of 1 kg B ha^-1 (B1), soil application of 2 kg B ha^-1 (B2), and foliar spray of 0.2% B (Bfs); three rice cultivars viz. Annapurna (HT stress tolerant), Naveen, and Shatabdi (both HT stress susceptible); and three temperature regimes viz. ambient (AT), HT at vegetative stage (HTV), and HT at reproductive stage (HTR). The results revealed that high temperature stress during vegetative or flowering stage reduced grain yield of rice cultivars mainly because of low pollen viability and spikelet fertility. The effects of high temperature on the spikelet fertility and grain filling varied among cultivars and the growth stages of plant when exposed to the high temperature stress. Under high temperature stress, the tolerant cultivar displays higher cell membrane stability, less accumulation of osmolytes, more antioxidant enzyme activities, and higher pollen viability and spikelet fertility than the susceptible cultivars. In the present work, soil application of boron was effective in reducing the negative effects of high temperature both at vegetative and reproductive stages. Application of B results into higher grain yield under both ambient and high temperature condition over control for all the three cultivars; however, more increase was observed for the susceptible cultivar over the tolerant one. The results suggest that the exogenous application of boron had a substantial effect on cell membrane stability, sugar mobilization, pollen viability, and spikelet fertility, hence the yield. The cultivars due to their variation in the tolerance level for high temperature stress behaved differently, and at high temperature stress, more response of the application of boron was seen in susceptible cultivars.

Greenhouse gas emissions and energy exchange in wet and dry season rice: eddy covariance-based approach

Lowland tropical rice-rice system has a unique micrometrological characteristic that affects both energy component and net ecosystem energy. Periodic and seasonal variations of methane (CH₄), carbon dioxide (CO₂), and energy exchange from irrigated lowland rice-rice ecosystem were studied using open-path eddy covariance (EC) system during the dry (DS) and wet (WS) seasons in 2015. Concurrently, the manual chamber method was employed in nitrous oxide (N₂O) measurement efflux. Cumulative net ecosystem carbon exchange (NEE) was observed highest (- 232.55 g C m^-2) during the WS and lowest (- 14.81 g C m^-2) during wet fallow (WF). Similarly, the cumulative net ecosystem methane exchange (NEME) was found highest (13,456.5 mg CH₄ m^-2) during the WS and lowest (2014.3 mg CH₄ m^-2) during the WF. Surface energy fluxes, i.e., sensible (Hs) and latent heat (LE) fluxes, showed a similar trend. With the advancement of time, the ratio of ecosystem respiration (Re) and gross primary production (GPP) increased. The cumulative global warming potential (GWP) for the two cropping seasons including two fallows was 13,224.1 kg CO₂ equivalent ha^-1. The GWP and NEME showed a similar trend as soil enzymes and labile carbon pools in both seasons (except GWP at the harvesting stage in the wet season). The mean NEE exhibited a more negative value with decrease in labile pools from panicle initiation to harvesting stage in the WS. Soil labile C and soil enzymes can be used as an indicator of NEE, NEME, and GWP in lowland rice ecology. Graphical abstract Schematic presentation of GHG emission and energy exchange in lowland rice.

Enhancement of toxic Cr (VI), Fe, and other heavy metals phytoremediation by the synergistic combination of native Bacillus cereus strain and Vetiveria zizanioides L

Bioremediation of Cr (VI), Fe, and other heavy metals (HMs) through plant-microbes interaction is one of the efficient strategies due to its high efficiency, low cost, and ecofriendly nature. The aim of the study was to isolate, characterize, and assess the potential of rhizospheric bacteria to enhance growth and metal accumulation by the chromium hyperaccumulator Vetiveria zizanoides. The bacterial strain isolated from mine tailings was identified to be Bacillus cereus (T1B3) strain exhibited plant growth-promoting traits including, 1-aminocyclopropane-1-carboxylate deaminase, indole acetic acid, and siderophores production, nitrogen fixation, and P solubilization. Removal capacity (mg L^-1) of T1B3 strain was 82% for Cr⁺⁶ (100), 92% for Fe (100), 67% for Mn(50), 36% for Zn (50), 31% for Cd (30), 25% for Cu (30), and 43% for Ni (50) during the active growth cycle in HM-amended, extract medium. Results indicate that inoculating the native V. zizanioides with T1B3 strain improves its phytoremediation efficiency of HMs. The mineralogical characteristics of chromite ore tailings and soil were also confirmed by X-ray diffraction, Fourier Transform Infrared, scanning electron microscope-energy dispersive spectroscopy analysis.

Enhanced and synergistic downregulation of oncogenic miRNAs by self-assembled branched DNA

miRNAs, a group of small non-coding RNA molecules, regulate the expression of many genes involved in various cellular processes. Acute evidence suggests that one miRNA can regulate many genes as its targets, while one gene can be targeted by many miRNAs that co-operatively regulate the gene. Thus, targeting a single miRNA is not sufficient enough to rescue the disease phenotype but it is also essential to target multiple miRNAs simultaneously. This inspired us to design a novel DNA nanostructure that can concurrently downregulate multiple oncomiRNAs. Here we designed a programmable antimiR branched DNA (antimiR-bDNA) nanostructure having antimiRNAs for selective binding to oncomiRNAs miRNA-27a, 96 and 182 which collectively downregulate FOXO1a expression. The antimiR-bDNAs show enhanced stability compared to naked antimiRNAs in serum and are able to knockdown these miRNAs with up to ∼50% greater repression as compared to antimiRNAs. This synergistic miRNA repression leads to the restoration of FOXO1a protein levels which in turn inhibit G1-S traversion in cancer cells. To the best of our knowledge, this is the first study harnessing the ability of bDNA structures to silence multiple miRNAs simultaneously.

Metagenomic assessment of methane production-oxidation and nitrogen metabolism of long term manured systems in lowland rice paddy

Biochemical pathways of methanogenesis and methanotrophy coupled with carbon (C)-nitrogen (N) metabolism were studied in long term (13years) manured systems in lowland rice paddy through metagenomics approach. Manured systems included in this study were, control (exclusion of application of any manure), farm yard manure (FYM, @5Mgha^-1yr^-1) and green manuring (GM with Sesbania aculeata). Metagenomic sequence data revealed the dominance of C decomposing bacterial communities' like Proteobacteria, Planctomycetes, Actinobacteria, Firmicutes, Acidobacteria, in manure amended soils as compared to control. Diversities for assimilatory and dissimilatory N-fixing microorganisms at phylum level were found higher under GM as compared to rest. Two genera responsible for methanogenesis, viz. Methanolobus and Methanotorris were absent in manured systems as compared to control. The acetoclastic and serine pathway was found as the predominant pathway for methanogenesis and methanotrophy, respectively, in tropical lowland rice paddy. Abundance reads of enzymes were in the range of 254-445 in the acetoclastic methanogenesis pathway. On the other hand, these were varied from 165 to 216 in serine pathway of methanotrophy. Lowland paddy soil exhibited higher functional and structural diversities in manured systems as compared to unamended control in respect to labile C pools and CH₄ production. Methane (CH₄) emission was 31% higher in FYM system than GM. However, nitrous oxide (N₂O) emission was found 25% higher in GM as compared to FYM. As a whole, bacterial diversities were higher under FYM system in tropical lowland rice paddy as compared to GM and unamended systems.

Elucidation of rice rhizosphere metagenome in relation to methane and nitrogen metabolism under elevated carbon dioxide and temperature using whole genome metagenomic approach

Carbon (C) and nitrogen (N) mineralization is one of the key processes of biogeochemical cycling in terrestrial ecosystem in general and rice ecology in particular. Rice rhizosphere is a rich niche of microbial diversity influenced by change in atmospheric temperature and concentration of carbon dioxide (CO2). Structural changes in microbial communities in rhizosphere influence the nutrient cycling. In the present study, the bacterial diversity and population dynamics were studied under ambient CO2 (a-CO2) and elevated CO2+temperature (e-CO2T) in lowland rice rhizosphere using whole genome metagenomic approach. The whole genome metagenomic sequence data of lowland rice exhibited the dominance of bacterial communities including Proteobacteria, Firmicutes, Acidobacteria, Actinobacteria and Planctomycetes. Interestingly, four genera related to methane production namely, Methanobacterium, Methanosphaera, Methanothermus and Methanothermococcus were absent in a-CO2 but noticed under e-CO2T. The acetoclastic pathway was found as the predominant pathway for methanogenesis, whereas, the serine pathway was found as the principal metabolic pathway for CH4 oxidation in lowland rice. The abundances of reads of enzymes in the acetoclastic methanogenesis pathway and serine pathways of methanotrophy were much higher in e-CO2T (328 and 182, respectively) as compared with a-CO2 (118 and 98, respectively). Rice rhizosphere showed higher structural diversities and functional activities in relation to N metabolism involving nitrogen fixation, assimilatory and dissimilatory nitrate reduction and denitrification under e-CO2T than that of a-CO2. Among the three pathways of N metabolism, dissimilarity pathways were predominant in lowland rice rhizosphere and more so under e-CO2T. Consequently, under e-CO2T, CH4 emission, microbial biomass nitrogen (MBN) and dehydrogenase activities were 45%, 20% and 35% higher than a-CO2, respectively. Holistically, a high bacterial diversity and abundances of C and N decomposing bacteria in lowland rice rhizosphere were found under e-CO2T, which could be explored further for their specific role in nutrient cycling, sustainable agriculture and environment management.

Impairment of soil health due to fly ash-fugitive dust deposition from coal-fired thermal power plants

Thermal power stations apart from being source of energy supply are causing soil pollution leading to its degradation in fertility and contamination. Fine particle and trace element emissions from energy production in coal-fired thermal power plants are associated with significant adverse effects on human, animal, and soil health. Contamination of soil with cadmium, nickel, copper, lead, arsenic, chromium, and zinc can be a primary route of human exposure to these potentially toxic elements. The environmental evaluation of surrounding soil of thermal power plants in Odisha may serve a model study to get the insight into hazards they are causing. The study investigates the impact of fly ash-fugitive dust (FAFD) deposition from coal-fired thermal power plant emissions on soil properties including trace element concentration, pH, and soil enzymatic activities. Higher FAFD deposition was found in the close proximity of power plants, which led to high pH and greater accumulation of heavy metals. Among the three power plants, in the vicinity of NALCO, higher concentrations of soil organic carbon and nitrogen was observed whereas, higher phosphorus content was recorded in the proximity of NTPC. Multivariate statistical analysis of different variables and their association indicated that FAFD deposition and soil properties were influenced by the source of emissions and distance from source of emission. Pollution in soil profiles and high risk areas were detected and visualized using surface maps based on Kriging interpolation. The concentrations of chromium and arsenic were higher in the soil where FAFD deposition was more. Observance of relatively high concentration of heavy metals like cadmium, lead, nickel, and arsenic and a low concentration of enzymatic activity in proximity to the emission source indicated a possible link with anthropogenic emissions.

Strain behavior and lattice dynamics in Ni50Mn35In15

The lattice dynamics in the polycrystalline shape-memory Heusler alloy Ni50Mn35In15 have been studied by means of resonant ultrasound spectroscopy (RUS). RUS spectra were collected in a frequency range 100-1200 kHz between 10 and 350 K. Ni50Mn35In15 exhibits a ferromagnetic transition at 313 K in the austenite phase and a martensitic transition at 248 K accompanied by a change of the magnetic state. Furthermore it displays a paramagnetic to ferrimagnetic transition within the martensitic phase. We determined the temperature dependence of the shear modulus and the acoustic attenuation of Ni50Mn35In15 and compared it with magnetization data. Following the structural softening, which accompanies the martensitic transition as a pretransitional phenomenon, a strong stiffening of the lattice is observed at the martensitic magneto-structural transition. Only a weak magnetoelastic coupling is evidenced at the Curie temperatures both in austenite and martensite phases. The large acoustic damping in the martensitic phase compared with the austenitic phase reflects the motion of the twin walls, which freezes out in the low temperature region.

Long-term effect of rice-based farming systems on soil health

Integrated rice-fish culture, an age-old farming system, is a technology which could produce rice and fish sustainably at a time by optimizing scarce resource use through complementary use of land and water. An understanding of microbial processes is important for the management of farming systems as soil microbes are the living part of soil organic matter and play critical roles in soil C and N cycling and ecosystem functioning of farming system. Rice-based integrated farming system model for small and marginal farmers was established in 2001 at Central Rice Research Institute, Cuttack, Odisha. The different enterprises of farming system were rice-fish, fish-fingerlings, fruits, vegetables, rice-fish refuge, and agroforestry. This study was conducted with the objective to assess the soil physicochemical properties, microbial population, carbon and nitrogen fractions, soil enzymatic activity, and productivity of different enterprises. The effect of enterprises induced significant changes in the chemical composition and organic matter which in turn influenced the activities of enzymes (urease, acid, and alkaline phosphatase) involved in the C, N, and P cycles. The different enterprises of long-term rice-based farming system caused significant variations in nutrient content of soil, which was higher in rice-fish refuge followed by rice-fish enterprise. Highest microbial populations and enzymatic properties were recorded in rice-fish refuge system because of waterlogging and reduced condition prolonged in this system leading to less decomposition of organic matter. The maximum alkaline phosphatase, urease, and FDA were observed in rice-fish enterprise. However, highest acid phosphatase and dehydrogenase activity were obtained in vegetable enterprise and fish-fingerlings enterprise, respectively.

Effect of fly ash application on soil microbial response and heavy metal accumulation in soil and rice plant

Fly ash (FA), a byproduct of coal combustion in thermal power plants, has been considered as a problematic solid waste and its safe disposal is a cause of concern. Several studies proposed that FA can be used as a soil additive; however its effect on microbial response, soil enzymatic activities and heavy metal accumulation in soil and grain of rice (cv. Naveen) to fly ash (FA) application was studied in a pot experiment during dry season 2011 in an Inceptisol. Fly ash was applied at a rate of zero per cent (FS), five per cent (FA5), ten per cent (FA10), twenty per cent (FA20), 40 per cent (FA40) and 100 per cent (FA100) on soil volume basis with nitrogen (N), phosphorus (P) and potassium (K) (40:20:20mg N:P:Kkg(-1) soil) with six replications. Heavy metals contents in soil and plant parts were analysed after harvest of crop. On the other hand, microbial population and soil enzymatic activities were analysed at panicle initiation stage (PI, 65 days after transplanting) of rice. There was no significant change in the concentration of zinc (Zn), iron (Fe), copper (Cu), manganese (Mn), cadmium (Cd) and chromium (Cr) with application of fly ash up to FA10. However, at FA100 there was significant increase of all metals concentration in soil than other treatments. Microorganisms differed in their response to the rate of FA application. Population of both fungi and actinomycetes decreased with the application of fly ash, while aerobic heterotrophic bacterial population did not change significantly up to FA40. On the other hand, total microbial activity measured in terms of Fluorescein diacetate (FDA) assay, and denitrifiers showed an increased trend up to FA40. However, activities of both alkaline and acid phosphatase were decreased with the application of FA. Application of FA at lower levels (ten to twenty per cent on soil volume basis) in soil enhanced micronutrients content, microbial activities and crop yield.