Thiourea supplementation mediated reduction of grain arsenic in rice (Oryza sativa L.) cultivars: A two year field study

Mitigating drought-induced oxidative stress in wheat (Triticum aestivum L.) through foliar application of sulfhydryl thiourea

Drought stress is a major abiotic stress affecting the performance of wheat (Triticum aestivum L.). The current study evaluated the effects of drought on wheat phenology, physiology, and biochemistry; and assessed the effectiveness of foliar-applied sulfhydryl thiourea to mitigate drought-induced oxidative stress. The treatments were: wheat varieties; V1 = Punjab-2011, V2 = Galaxy-2013, V3 = Ujala-2016, and V4 = Anaaj-2017, drought stress; D1 = control (80% field capacity [FC]) and D2 = drought stress (40% FC), at  the reproductive stage, and sulfhydryl thiourea (S) applications; S0 = control-no thiourea and S1 = foliar thiourea application @ 500 mg L-1. Results of this study indicated that growth parameters, including height, dry weight, leaf area index (LAI), leaf area duration (LAD), crop growth rate (CGR), net assimilation rate (NAR) were decreased under drought stress-40% FC, as compared to control-80% FC. Drought stress reduced the photosynthetic efficiency, water potential, transpiration rates, stomatal conductances, and relative water contents by 18, 17, 26, 29, and 55% in wheat varieties as compared to control. In addition, foliar chlorophyll a, and b contents were also lowered under drought stress in all wheat varieties due to an increase in malondialdehyde and electrolyte leakage. Interestingly, thiourea applications restored wheat growth and yield attributes by improving the production and activities of proline, antioxidants, and osmolytes under normal and drought stress as compared to control. Thiourea applications improved the osmolyte defense in wheat varieties as peroxidase, superoxide dismutase, catalase, proline, glycine betaine, and total phenolic were increased by 13, 20, 12, 17, 23, and 52%; while reducing the electrolyte leakage and malondialdehyde content by 49 and 32% as compared to control. Among the wheat varieties, Anaaj-2017 showed better resilience towards drought stress and also gave better response towards thiourea application based on morpho-physiological, biochemical, and yield attributes as compared to Punjab-2011, Galaxy-2013, and Ujala-2016. Eta-square values showed that thiourea applications, drought stress, and wheat varieties were key contributors to most of the parameters measured. In conclusion, the sulfhydryl thiourea applications improved the morpho-physiology, biochemical, and yield attributes of wheat varieties, thereby mitigating the adverse effects of drought.  Moving forward, detailed studies pertaining to the molecular and genetic mechanisms under sulfhydryl thiourea-induced drought stress tolerance are warranted.

Emerging concern of nano-pollution in agro-ecosystem: Flip side of nanotechnology

Nanomaterials (NMs) have proven to be a game-changer in agriculture, showcasing their potential to boost plant growth and safeguarding crops. The agricultural sector has widely adopted NMs, benefiting from their small size, high surface area, and optical properties to augment crop productivity and provide protection against various stressors. This is attributed to their unique characteristics, contributing to their widespread use in agriculture. Human exposure from various components of agro-environmental sectors (soil, crops) NMs residues are likely to upsurge with exposure paths may stimulates bioaccumulation in food chain. With the aim to achieve sustainability, nanotechnology (NTs) do exhibit its potentials in various domains of agriculture also have its flip side too. In this review article we have opted a fusion approach using bibliometric based analysis of global research trend followed by a holistic assessment of pros and cons i.e. toxicological aspect too. Moreover, we have also tried to analyse the current scenario of policy associated with the application of NMs in agro-environment.

Vetiver grass cleans up arsenic contaminated field for subsequent safe cultivation of rice with low arsenic in grains: A two year field study

The presence of high concentrations of arsenic (As) in agricultural soils and its subsequent accumulation in rice crop is a serious issue threatening sustainability of agriculture and human health. In the present work, remediation of As contaminated field in Nadia, West Bengal, India was done through the cultivation of Vetiver (Vetiveria zizanoides L. Nash) and the same field was subsequently used for rice (Oryza sativa L.) cultivation. The results showed that V. zizanoides could reduce As concentrations in the field to bring it lower than the maximum permissible limit (20 mg kg-1) in 11 months' time. The rice plants grown in remediated field showed improvement in growth and photosynthesis parameters as compared to that of contaminated field. Importantly, yield related parameters (filled seed, 1000 grain weight, number of panicles etc.) were also significantly higher in remediated field than that in contaminated field. Arsenic concentration in roots, shoot, husk and grains of rice was found to be significantly lower in remediated field than in contaminated field. Grain As decreased from 0.75 to 0.77 μg g-1 dw in contaminated field to 0.15-0.18 μg g-1 dw. In conclusion, replacing rice for single year with V. zizanoides crop can significantly remediate the field and can be a viable option.

An assessment of the impact of traditional rice cooking practice and eating habits on arsenic and iron transfer into the food chain of smallholders of Indo-Gangetic plain of South-Asia: Using AMMI and Monte-Carlo simulation model

The current study was designed to investigate the consequences of rice cooking and soaking of cooked rice (CR) with or without arsenic (As) contaminated water on As and Fe (iron) transfer to the human body along with associated health risk assessment using additive main-effects and multiplicative interaction (AMMI) and Monte Carlo Simulation model. In comparison to raw rice, As content in cooked rice (CR) and soaked cooked rice (SCR) enhanced significantly (at p < 0.05 level), regardless of rice cultivars and locations (at p < 0.05 level) due to the use of As-rich water for cooking and soaking purposes. Whereas As content in CR and SCR was reduced significantly due to the use of As-free water for cooking and soaking purposes. The use of As-free water (AFW) also enhanced the Fe content in CR. The overnight soaking of rice invariably enhanced the Fe content despite the use of As-contaminated water in SCR however, comparatively in lesser amount than As-free rice. In the studied area, due to consumption of As-rich CR and SCR children are more vulnerable to health hazards than adults. Consumption of SCR (prepared with AFW) could be an effective method to minimize As transmission and Fe enrichment among consumers.

An extensive review of arsenic dynamics and its distribution in soil-aqueous-rice plant systems in south and Southeast Asia with bibliographic and meta-data analysis

Millions of people worldwide are affected by arsenic (As) contamination, particularly in South and Southeast Asian countries, where large-scale dependence on the usage of As-contaminated groundwater in drinking and irrigation is a familiar practice. Rice (Oryza sativa) cultivation is commonly done in South and Southeast Asian countries as a preferable crop which takes up more As than any other cereals. The present article has performed a scientific meta-data analysis and extensive bibliometric analysis to demonstrate the research trend in global rice As contamination scenario in the timeframe of 1980-2023. This study identified that China contributes most with the maximum number of publications followed by India, USA, UK and Bangladesh. The two words 'arsenic' and 'rice' have been identified as the most dominant keywords used by the authors, found through co-occurrence cluster analysis with author keyword association study. The comprehensive perceptive attained about the factors affecting As load in plant tissue and the nature of the micro-environment augment the contamination of rice cultivars in the region. This extensive review analyses soil parameters through meta-data regression assessment that influence and control As dynamics in soil with its further loading into rice grains and presents that As content and OM are inversely related and slightly correlated to the pH increment of the soil. Additionally, irrigation and water management practices have been found as a potential modulator of soil As concentration and bioavailability, presented through a linear fit with 95% confidence interval method.

Selenium - An environmentally friendly micronutrient in agroecosystem in the modern era: An overview of 50-year findings

Agricultural productivity is constantly being forced to maintain yield stability to feed the enormously growing world population. However, shrinking arable and nutrient-deprived soil and abiotic and biotic stressor (s) in different magnitudes put additional challenges to achieving global food security. Though well-defined, the concept of macro, micronutrients, and beneficial elements is from a plant nutritional perspective. Among various micronutrients, selenium (Se) is essential in small amounts for the life cycle of organisms, including crops. Selenium has the potential to improve soil health, leading to the improvement of productivity and crop quality. However, Se possesses an immense encouraging phenomenon when supplied within the threshold limit, also having wide variations. The supplementation of Se has exhibited promising outcomes in lessening biotic and abiotic stress in various crops. Besides, bulk form, nano-Se, and biogenic-Se also revealed some merits and limitations. Literature suggests that the possibilities of biogenic-Se in stress alleviation and fortifying foods are encouraging. In this article, apart from adopting a combination of a conventional extensive review of the literature and bibliometric analysis, the authors have assessed the journey of Se in the "soil to spoon" perspective in a diverse agroecosystem to highlight the research gap area. There is no doubt that the time has come to seriously consider the tag of beneficial elements associated with Se, especially in the drastic global climate change era.

Zinc oxide nanorod/rutin modified electrode for the detection of Thiourea in real samples

In this work, a novel electrochemical detection strategy was developed based on a metal-organic framework of zinc oxide nanorod nanoparticles and rutin for selective screening of Thiourea as toxic chemicals. The zinc oxide nanorod were synthesized by following direct chemical precipitation methods and characterized by X-ray diffraction and X-ray photoelectron spectroscopy analysis. The surface of modified electrodes was also characterized by field emission scanning electron microscopes, energy-dispersive X-ray spectroscopy, and attenuated total reflectance flourier transform infrared spectroscopy. Furthermore, the electrochemical activity of the developed sensor was tested by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. The modified electrode showed outstanding electro-catalytic activity towards the detection of Thiourea in phosphate buffer saline at a high pH level of 12.0. The proposed sensor showed a linear range of linearity in a concentration ranging from 5.0 × 10-6 - 900 × 10-6 molL-1 and a detection limit of 2.0 × 10-6 molL-1. Moreover, the selectivity of the developed electrochemical sensor was investigated for the detection of Thiourea in the presence of organic compounds and a group of anions. Furthermore, the proposed strategy demonstrated an excellent recovery value in the spiked farmland water and fruit juice sample.

Nocardiopsis lucentensis and thiourea co-application mitigates arsenic stress through enhanced antioxidant metabolism and lignin accumulation in rice

Arsenic (As) is a group-1 carcinogenic metalloid that threatens global food safety and security, primarily via its phytotoxicity in the staple crop rice. In the present study, ThioAC, the co-application of thiourea (TU, a non-physiological redox regulator) and N. lucentensis (Act, an As-detoxifying actinobacteria), was evaluated as a low-cost approach for alleviating As(III) toxicity in rice. To this end, we phenotyped rice seedlings subjected to 400 mg kg^-1 As(III) with/without TU, Act or ThioAC and analyzed their redox status. Under As-stress conditions, ThioAC treatment stabilized photosynthetic performance, as indicated by 78 % higher total chlorophyll accumulation and 81 % higher leaf biomass, compared with those of As-stressed plants. Further, ThioAC improved root lignin levels (2.08-fold) by activating the key enzymes of lignin biosynthesis under As-stress. The extent of reduction in total As under ThioAC (36 %) was significantly higher than TU (26 %) and Act (12 %), compared to those of As-alone treatment, indicating their synergistic interaction. The supplementation of TU and Act activated enzymatic and non-enzymatic antioxidant systems, respectively, with a preference for young (TU) and old (Act) leaves. Additionally, ThioAC activated enzymatic antioxidants, specifically GR (∼3-fold), in a leaf-age specific manner and suppressed ROS-producing enzymes to near-control levels. This coincided with 2-fold higher induction of polyphenols and metallothionins in ThioAC-supplemented plants, resulting in improved antioxidant defence against As-stress. Thus, our findings highlighted ThioAC application as a robust, cost-effective ameliorative strategy, for achieving As-stress mitigation in a sustainable manner.

Bacterial consortium (Priestia endophytica NDAS01F, Bacillus licheniformis NDSA24R, and Priestia flexa NDAS28R) and thiourea mediated amelioration of arsenic stress and growth improvement of Oryza sativa L

The present study analyzed the effects of individual microbes and their consortium (Priestia endophytica NDAS01F, Bacillus licheniformis NDSA24R, and P. flexa NDAS28R) either alone or in interaction with thiourea (TU) on growth and responses of rice plants subjected to As stress (50 mg kg^-1 in soil) in a pot experiment. The bacteria used in the experiment were isolated from As contaminated fields of Nadia, West Bengal and showed significant As removal potential in in vitro experiment. The results revealed significant growth improvement, biomass accumulation, and decline in malondialdehyde levels in rice plants in bacterial and TU treatments as compared to control As treatment. The best results were observed in a bacterial consortium (B1-2-3), which induced a profound increase of 65%, 43%, 127% and 83% in root length, shoot length, leaf width and fresh weight, respectively. Sulfur metabolism and cell wall synthesis were stimulated upon bacterial and TU amendment in plants. The maximum reduction in As concentration was observed in B2 in roots (-55%) and in B1-2-3 in shoot (-83%). The combined treatment of B1-2-3 + TU proved to be less effective as compared to that of B1-2-3 in terms of As reduction and growth improvement. Hence, the usage of bacterial consortium obtained in the present work is a sustainable approach, which might find relevance in field conditions to achieve As reduction in rice grains and to attain higher growth of plants without the need for additional TU supplementation.

Human health risk mitigation from arsenic in rice by crop rotation with a hyperaccumulator plant

Exposure to arsenic (As) from a diet of contaminated rice is a widespread problem and a serious concern in several parts of the world. There is a need to develop sustainable, effective, and reliable strategies to reduce As accumulation in rice. Our goal was to develop and test a simple crop rotation method of alternating rice with the As hyperaccumulator plant, Chinese brake fern (Pteris vitatta L.), to reduce As concentrations in rice grains. A greenhouse column study was performed for 2 years using As-contaminated rice paddy soil from West Bengal. Rice was grown under flooded conditions and irrigated with As-contaminated water to simulate field conditions. Chinese brake fern was grown between two rice cycles in experimental columns, while control columns were left unplanted. Our results show that at the end of two cycles, there was a statistically significant decrease in soil As concentrations in the treatment columns compared to the control columns. After one rotation with the fern, there was a significant decline in As concentrations in rice grains in treatment plants and a concomitant decline in both noncarcinogenic and carcinogenic health risks. Our results indicate that there could be substantial benefit in implementing this simple crop rotation model to help lower human health risks from As exposure via rice ingestion.

Iron oxide doped rice biochar reduces soil-plant arsenic stress, improves nutrient values: An amendment towards sustainable development goals

Arsenic (As) contamination in paddy soils and its further translocation to the rice is a serious global issue. Arsenic loading to the rice depends on soil physico-chemical parameters and agronomic practices. To minimize this natural threat, as a natural substance, rice straw was used to produce rice biochar (RBC) and doped with iron oxide (IO) nanoparticles, another eco-friendly composite. In this study, RBC was used at three different concentrations- 0.5%, 1%, and 1.5% alone as well as conjugated with fixed 20 ppm IO nanoparticles. These treatments were compared with the control soil and control plants that had only As in the setup, without any amendments. The application of these treatments was efficient in reducing soil As bioavailability by 43.9%, 60.5%, and 57.3% respectively. Experimental data proved a significant percentage of As was adsorbed onto the RBC + IO conjugate. Further, the 1% RBC + IO conjugate was found to be the best treatment in terms of making soil macro-nutrients bioavailable. Rice seedlings grown under this treatment was more stress tolerant and produced less antioxidant enzymes and stress markers compared to the control plants grown under As-stress only. Rice plants from these different growth setups were observed for internal anatomical integrity and found that the RBC alone and RBC + IO conjugate, both improved the internal vascular structure compared to the control plants. To minimize soil As stress in crops, IO-doped RBC was proven to be the best sustainable amendment for improving soil-crop quality and achieving the proposed motto of Sustainable Development Goals by the United Nations.

Arsenic accumulation in rice: Alternative irrigation regimes produce rice safe from arsenic contamination

The natural occurrence of arsenic (As) in groundwater & soils and its bioaccumulation in rice grains is a major health concern worldwide. To combat the problem, best combination of irrigation management and suitable rice variety altering As content in grains must be ensured. With this aim, a field trial was conducted with two rice varieties and water management including alternate wetting and drying (AWD) and continuous flooding (CF) irrigation regimes with As contaminated groundwater (AsW) and temporarily stored groundwater (TSG) and river water for only CF (as control). Results revealed that As content in different portions of paddy plant was significantly different (P < 0.001) with irrigation practices and rice varieties. AWD irrigation with TSG accumulated lower As in rice grains compared with CF-AsW for both varieties. Data showed that AWD-TSG practice led to 61.37% and 60.34% grain As reduction for BRRI dhan28 and BRRI dhan29, respectively, compared with CF-AsW. For Principle Component Analysis (PCA), first principle component (PC1) explained 91.7% of the variability and irrigation water As, soil total and available As, straw As, root As and husk As were the dominating parameters. With significant (P < 0.05) variation in yields between the genotypes, AWD increased grain yield by 29.25% in BRRI dhan29 Compared with CF. However, translocation factor (TF) and bioconcentration factor (BCF) for both varieties were less than one for all the treatments. The addition of this study to our knowledge base is that, AWD-TSG with BRRI dhan29 can be an As-safe practice without compromising yields.

Thiourea mediated ROS-metabolites reprogramming restores root system architecture under arsenic stress in rice

Arsenic (As) is a ubiquitous carcinogenic metalloid that enters into human food chain, through rice consumption. To unravel the conundrum of oxidative vs. reductive stress, the differential root-system architecture (RSA) was studied under As (a ROS producer) and thiourea (TU; a ROS scavenger) alone treatments, which indicated 0.80- and 0.74-fold reduction in the number of lateral roots (NLR), respectively compared with those of control. In case of As+TU treatment, NLR was increased by 4.35-fold compared with those of As-stress, which coincided with partial restoration of redox-status and auxin transport towards the root-tip. The expression levels of 16 ROS related genes, including RBOHC, UPB-1 C, SHR1, PUCHI, were quantified which provided the molecular fingerprint, in accordance with endogenous ROS signature. LC-MS based untargeted and targeted metabolomics data revealed that As-induced oxidative stress was metabolically more challenging than TU alone-induced reductive stress. Cis/trans-ferruloyl putrescine and γ-glutamyl leucine were identified as novel As-responsive metabolites whose levels were decreased and increased, respectively under As+TU than As-treated roots. In addition, the overall amino acid accumulation was increased in As+TU than As-treated roots, indicating the improved nutritional availability. Thus, the study revealed dynamic interplay between "ROS-metabolites-RSA", to the broader context of TU-mediated amelioration of As-stress in rice.

An assessment of various potentially toxic elements and associated health risks in agricultural soil along the middle Gangetic basin, India

The present study analysed the levels of potentially toxic elements along with physico-chemical properties of agricultural soil samples (n = 59) collected from fields situated along the path of river Ganga in the middle Gangetic floodplain in two districts, Ballia and Ghazipur. Arsenic (As), chromium (Cr), copper (Cu), nickel (Ni), zinc (Zn), lead (Pb), iron (Fe) and manganese (Mn) levels were analysed by Wavelength Dispersive-X-Ray Fluorescence Spectroscopy (WD-XRF) and the associated health risks along with diverse indices were calculated. The mean concentrations of As, Cu, Cr, Pb, Zn and Ni were found to be 15, 42, 85, 18, 87 and 47 mg kg^-1, respectively in Ballia and 13, 31, 73, 22, 77 and 34 mg kg^-1, respectively in Ghazipur. Physico-chemical properties like pH, ORP and organic matter were found to be 7.91, 209 and 1.20, respectively in Ballia and 8.51, 155 and 1.25, respectively in Ghazipur. The calculated health quotient (HQ) for all the elements was observed to be within the threshold value of one, however with few exemptions. Therefore, the present study showcases the contamination of potentially toxic elements in agricultural fields and possible health hazards for people.

Recent advances in arsenic mitigation in rice through biotechnological approaches

Arsenic (As) is a major threat to the environment and human health due to its toxicity and carcinogenicity. Occurrence of alarming concentrations of As in water and soil leads to its bioaccumulation in crops which is a major health concern globally. Rice (Oryza sativa) is a staple food for a large population staying in As contaminated areas so, it is of utmost importance to reduce As levels in rice, especially grains. Amongst several strategies in practice, biotechnology may provide an effective option to reduce As accumulation in rice grains. Genetic engineering can be a viable approach to exploit potential genes playing roles in As metabolism pathway in plants. Besides, developing low As accumulating rice varieties through breeding is also an important area. Identifying genotypic variation in rice is a crucial step toward the development of a safe rice cultivar for growing in As-affected areas. Significant genotypic variation has been found in rice varieties for As accumulation in grains and that is attributable to differential expression of transporters, radial oxygen loss, and other regulators of As stress. This review provides recent updates on the research advances leading to transgenic and breeding approaches adopted to reduce As levels in rice, especially grains.

Exogenously-applied L-glutamic acid protects photosynthetic functions and enhances arsenic tolerance through increased nitrogen assimilation and antioxidant capacity in rice (Oryza sativa L.)

L-Glutamic acid (Glu) is used as an effective bio-stimulant to reduce arsenic (As) stress in plants. The role of Glu was studied in the protection of photosynthesis and growth of rice (Oryza sativa L. Japonica Type Taipie-309) plants grown with 50 μM As stress by studying the oxidative stress, photosynthetic and growth characteristics. Among the Glu concentrations (0, 2.5, 5 and 10 μM), 10 μM Glu maximally enhanced photosynthesis and growth parameters with the least cellular oxidative stress level. The supplementation of 10 μM Glu resulted in the reduced effects of As stress on gas exchange parameters, PSII activity and growth attributes through enhancement of antioxidant and proline metabolism. The enzymes of nitrogen (N) assimilation, such as nitrate reductase, nitrite reductase, glutamine synthetase and glutamate synthase were increased with Glu treatment under As stress. The Glu-induced metabolite synthesis showed the role of various metabolites in As stress responses. The role of Glu as a signalling molecule in reducing the adverse effects of As through accelerating the antioxidant enzymes, PSII activity, proline metabolism and nitrogen assimilation has been discussed.

Antioxidant enzymes and transporter genes mediate arsenic stress reduction in rice (Oryza sativa L.) upon thiourea supplementation

Thiourea (TU) is a chemo-priming agent and non-physiological reactive oxygen species (ROS) scavenger whose application has been found to reduce As accumulation in rice grains along with improved growth and yield. The present field study explored TU-mediated mechanistic changes in silicon (Si) assimilation in root/shoot, biochemical and molecular mechanisms of arsenic (As) stress amelioration in rice cultivars. Gosai and Satabdi (IET-4786) rice cultivars were selected for field experiment at three different places; control field and two other As contaminated experimental fields (EF1 and EF2) in West Bengal, India. The average As reduction was observed to be 9.5% and 19.8% whereas the yield increment was 8.8% and 17.7% for gosai and satabdi, respectively among all the three experimental fields. The positive interrelation was also observed between improved internal ultrastructure anatomy and enhanced Si assimilation (36%-423%) upon TU application. The level of photosynthetic pigments was increased by 29.8%-99.2%. Further, activities of antioxidant enzymes were harmonically altered in TU supplemented plants. The expression of various As related transporter genes in flag leaf and developing grains (inflorescence) was changed in both the rice cultivars (gosai and satabdi). It was also presumably responsible for observed As reduction in grains. Thus, TU application was found to be an efficient and sustainable agronomic practice for amelioration of As toxicity in rice plants in As contaminated field conditions.

Enhanced phytoremediation of Metal(loid)s via spiked ZVI nanoparticles: An urban clean-up strategy with ornamental plants

The increasing industrialization and urbanization are also triggering environmental pollution, mostly unnoticed, in the case of soil pollution due to uncontrolled contamination by toxic elemental dispersion. The present study focused on this aspect and studied the clean-up of urban soil in a low-cost and eco-friendly way to restrict arsenic (As), lead (Pb) and mercury (Hg) contamination. Four potential ornamental plants, Catharanthus roseus (vinca), Cosmos bipinnatus (cosmos), Gomphrena globose (globosa) and Impatiens balsamina (balsamina) were used along with zero valent iron (ZVI) nanoparticles (Fe NPs) for remediation of the soil spiked with As (70 mg kg-1), Pb (600 mg kg-1) and Hg (15 mg kg-1) in a 60 d pot experiment. All plants were divided into four groups viz. control, spiked, spiked+20 mg kg-1 ZVI NP and spiked+50 mg kg-1 ZVI NP. FTIR and SEM were used for ZVI NP characterization. Soil and plant analyses and elemental assessments were done using ICP-MS, XRF and SEM. Among the four plants, cosmos showed the maximum accumulation of toxic elements (41.24 ± 0.022 mg kg-1 As, 139.15 ± 11.2 mg kg-1 Pb and 15.57 ± 0.27 mg kg-1 Hg) at 60 d. The application of ZVI NP at 20 mg kg-1 dosage was found to further augment plants' potential for metal(loid)s accumulation without negatively hampering their growth. Cosmos were observed to reduce soil As from 81.35 ± 1.34 mg kg-1 to 28.16 ± 1.38 mg kg-1 (65.38%), Pb from 1132.47 ± 4.66 to 516.09 ± 3.15 mg kg-1 (54.42%) and Hg from 17.35 ± 0.88 to 6.65 ± 0.4 mg kg-1 (61.67%) at 60 d in spiked + 20 mg kg-1 ZVI NP treatment. Balsamina was the most sensitive plant and showed the least metal(loid)s accumulation. In conclusion, three of these plants are potent enough to use together for a better and enhanced removal of toxic elements from the contaminated soil with cosmos to be the best amongst these in urban areas.

Arsenic contamination, impact and mitigation strategies in rice agro-environment: An inclusive insight

Arsenic (As) contamination and its adverse consequences on rice agroecosystem are well known. Rice has the credit to feed more than 50% of the world population but concurrently, rice accumulates a substantial amount of As, thereby compromising food security. The gravity of the situation lays in the fact that the population in theAs uncontaminated areas may be accidentally exposed to toxic levels of As from rice consumption. In this review, we are trying to summarize the documents on the impact of As contamination and phytotoxicity in past two decades. The unique feature of this attempt is wide spectrum coverages of topics, and that makes it truly an interdisciplinary review. Aprat from the behaviour of As in rice field soil, we have documented the cellular and molecular response of rice plant upon exposure to As. The potential of various mitigation strategies with particular emphasis on using biochar, seed priming technology, irrigation management, transgenic variety development and other agronomic methods have been critically explored. The review attempts to give a comprehensive and multidiciplinary insight into the behaviour of As in Paddy -Water - Soil - Plate prospective from molecular to post-harvest phase. From the comprehensive literature review, we may conclude that considerable emphasis on rice grain, nutritional and anti-nutritional components, and grain quality traits under arsenic stress condition is yet to be given. Besides these, some emerging mitigation options like seed priming technology, adoption of nanotechnological strategies, applications of biochar should be fortified in large scale without interfering with the proper use of biodiversity.