Rengasamy Parthasarathi

The increasing demand for sustainable agricultural production, coupled with declining soil health, inefficient nutrient use and poor irrigation water quality, necessitates the development of innovative and eco-friendly technologies. Among the nanomaterials, two-dimensional graphene oxide (GO) has gained attention due to their extraordinary physical and chemical properties, including high specific surface area, a better number of oxygen-containing functional groups, high adsorption capacity and surface chemistry. Green synthesis approaches using biomass, agricultural residues and plant extracts are highlighted for their potential to reduce environmental impacts and promote sustainable nanomaterial production. This review further discusses advanced characterisation methods such as Fourier transform infrared spectroscopy, x-ray diffraction pattern, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller surface area analysis and x-ray photoelectron spectroscopy for understanding their structure and function. These analytical techniques provide critical insights into the structural attributes that determine the agricultural performance of GO nanomaterials. Soil–nanomaterial interactions, adsorption of nutrients, controlled release of nutrients and removal of sodium ions from saline irrigation water were thoroughly assessed. Based on existing evidence, application of GO may enhance soil aggregation, water holding capacity, nutrient utilisation efficiency and irrigation water quality and help sustain crop production. However, challenges related to large-scale production, long-term environmental fate, biosafety, economic viability and regulatory standardisation have hindered widespread adoption in agriculture. Future research should prioritise scalable and cost-effective production technologies, long-term field validation, standardised risk assessment protocols and integration with precision agriculture to facilitate commercial adoption.

In water-scarce peri-urban agriculture systems of South and Southeast Asia, the use of industrial effluents for irrigation is gaining momentum. Okra (Abelmoschus esculentus (L.) Moench), being a popular vegetable crop, is grown under effluent-irrigated conditions due to its adaptability and economic importance. The review presented here compiles research articles published from 2000 to 2025 studying the effects of irrigation with distillery, textile, tannery, paper and pulp and sugar mill effluents on okra, focusing on plant growth, physiological response, soil health and heavy metal accumulation. Accumulated evidence demonstrates a concentration-dependent response of okra and soil systems to industrial effluent irrigation. Effluent suitability for agriculture is strongly industry-dependent: distillery and sugar mill effluents, at low dilution, supply useful nitrogen (N), potassium (K) and organic matter with comparatively lower heavy-metal risk, whereas tannery and textile dyeing effluents carry substantially higher chromium, cadmium and lead loads and require treatment before safe reuse. Nitrogen, phosphorus (P), K and organic matter are often supplemented for improved seed germination, vegetative development, chlorophyll production, yield and nutrient availability, particularly at low effluent dilutions (5–25 %). Osmotic stress, oxidative damage, growth inhibition and a reduction in photosynthetic activity occur at concentrations exceeding 50 %. Regardless of effluent type, continued irrigation increases soil salt content, alters microbial and enzyme activity and drives accumulation of heavy metals cadmium, chromium, lead and nickel, which translocate to edible pods and can exceed recommended food safety limits, posing a measurable health concern. Knowledge gaps remain regarding varietal differences in metal uptake, stress tolerance mechanisms, molecular responses and their long-term field-scale implications under tropical conditions. Mitigation strategies showing the most promise include biochar amendment, phytoremediation crop rotation, constructed wetland pre-treatment and precision dilution.

Rice (Oryza sativa L.) is a staple food for over 3.5 billion people worldwide; however, its production is increasingly threatened by climate change-induced drought, soil salinity and heat stress. Silicon (Si) is a beneficial and quasi-essential element and has been researched extensively for mitigating the effects of abiotic stresses in rice. Recent advances have focused on developing highly bioavailable Si delivery systems, including nano-silica nanoparticles (SiNPs) and Si-based biostimulants. This review synthesises current knowledge on Si dynamics in soil–plant systems, the physicochemical properties of nano-silica and major application strategies reported for rice cultivation. Mechanistic areas covered include enhancement of abiotic stress tolerance (drought, salt and heat stress), activation of the antioxidant defence, maintenance of photosynthesis, nitrogen-use efficiency (NUE), hormonal signalling mechanisms and rice blast (Magnaporthe oryzae) and sheath blight (Rhizoctonia solani) resistance. Environmental safety issues, regulatory considerations and future perspectives in precision and sustainable agriculture are also discussed. The on-farm adoption barriers and key research needs are highlighted throughout. Unlike earlier reviews focused primarily on conventional Si fertilisation, this review emphasises recent advances in nano-silica technologies, Si-based biostimulants and their relevance to climate-resilient rice production.

Polystyrene (PS) is a widely used synthetic plastic known for its durability, low cost, and versatility; it is easily available in the market. Despite its numerous advantages, the increasing PS accumulation results in serious environmental contamination that greatly adds to the world’s plastic waste problem. Common variants of PS, such as high-impact polystyrene (HIPS), expanded polystyrene (EPS) and general-purpose polystyrene (GPPS), endure in ecosystems and, during degradation, emit detrimental chemicals, microplastics, and nanoplastics that adversely impact soil, water, and living organisms. Biodegradation using microorganisms has emerged as a sustainable alternative to conventional disposal methods like landfilling and incineration. Various microorganisms, including both fungi and bacteria, have the ability to degrade PS. These microorganisms secrete enzymes (e.g., laccase, esterase, lipases, and monooxygenases), which initiate a series of biochemical reactions that convert PS into non-toxic compounds, such as CO₂ and H₂O. Analytical techniques like depolymerase assay, biofilm formation assay, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Gas chromatography-mass spectroscopy (GC-MS) were employed to study these biodegradation processes and monitor the physical and chemical changes in polymer structure during microbial activity. This review highlights the potential role of microorganisms and their enzymes in managing PS waste to mitigate environmental pollution and facilitate the transition to a circular economy.

Microbial biofilms are organised populations of microbes covered with a self-made extracellular polymeric matrix and are at the core of climate-smart farming and sustainable agriculture. Biofilms enhance soil health by stabilising soil structures, enhancing microbial diversity and promoting nutrient cycling and thereby naturally supporting plant growth and resilience. One way biofilm-forming plant growth promoting rhizobacteria (PGPR) might be helping plants is by making them better able to take up nutrients through the solubilization of elements such as nitrogen, phosphorus and potassium; at the same time, they release phytohormones and compounds that alleviate stress to make plants resistant to abiotic stresses like salinity and drought. Root colonisation becomes more durable and pathogen biocontrol can be done more efficiently by biofilm matrices, which protect microorganisms from environmental stresses. Rhizospheric interactions exemplified by cross-kingdom biofilms with fungi are the most effective ways to exchange nutrients and enhance ecosystem resilience. The growth of stable biofilm communities and their microbial diversity can be supported by agricultural techniques such as the use of organic additives and conservation tillage. Recent developments emphasise the use of biofilm-based inoculants as biofertilizers, bio-stimulants and biocontrol agents in an effort to lower chemical inputs and greenhouse gas emissions in agroecosystems. More research and innovative applications like multi-strain consortia and biofilm-enhanced seed coating provide promising ways of harnessing microbial biofilms for increased agricultural productivity and soil quality, as well as environmental sustainability in the face of climate change.

Rice, the staple food crop of half of the world population, is challenged by biotic and abiotic stresses which affect its productivity. Sustainable rice production will ensure safeguard food security. It involves genetic background, climate and soil factors. Development of low-input response varieties by genetically associating microbiomes involved in functional activities of rice growth and development offers scope for sustainability. This review focuses on genetics influence on microbiome connections and use of these microbiome associations to create low-input responsive rice varieties. Root exudates from traditional varieties with specific traits and unique microbiomes associations can prove useful in developing low-input rice varieties. Analysis of functional traits such as nutrient mobilization, resistance to pests and adaptation for abiotic stresses in various germplasm lines can help identify suitable parent plants for breeding. Study of the genetic mechanisms of microbiome association through QTL mapping and transcriptomic analysis identifying the genomic regions regulating the microbiome-related traits. Traditional breeding methods, marker-assisted techniques and rapid generation advancement strategies can be used to develop lines for evaluation. It involves screening methods, identification of selection parameters, inheritance pattern and optimization of field plot conditions need to be considered while developing the superior varieties. The evaluation pattern will be studied in various trials for studying the genotype x environment interactions and better lines will be identified for varietal release. The low-input response rice variety will be able to deploy specific microbes for functional activities.

This study aims to investigate the biodegradation potential of a gut bacterial strain, Bacillus cereus AP-01, isolated from Tenebrio molitor larvae fed Styrofoam, focusing on its efficacy in degrading low-density polyethylene (LDPE). The biodegradation process was evaluated through a series of assays, including clear zone assays, biodegradation assays, and planktonic cell growth assessments in mineral salt medium (MSM) over a 28-day incubation period. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were employed to characterize the alterations in LDPE pellets, followed by molecular characterization. Over three months, sterile soil + LDPE pellets were treated with different concentrations of gut bacterial strain. The degradation capabilities were assessed by measuring pH, total microbial counts, carbon dioxide evolution, weight loss, and conducting phase contrast microscopy and mechanical strength tests. Results demonstrated that MSM containing LDPE as a carbon source with gut bacterial strain produced a clear zone and enhanced planktonic cell growth. FTIR analysis revealed the formation of new functional groups in the LDPE, while SEM images displayed surface erosion and cracking, providing visual evidence of biodegradation. Molecular characterization confirmed the strain as Bacillus cereus AP-01 (NCBI Accession Number: OR288218.1). A 10% inoculum concentration of Bacillus cereus AP-01 exhibited increased soil bacterial counts, carbon dioxide evolution, and pH levels, alongside a notable weight loss of 30.3% in LDPE pellets. Mechanical strength assessments indicated substantial reductions in tensile strength (7.81 ± 0.84 MPa), compression (4.92 ± 0.53 MPa), hardness (51.96 ± 5.62 shore D), flexibility (10.62 ± 1.15 MPa), and impact resistance (14.79 ± 0.94 J). These findings underscore the biodegradation potential of Bacillus cereus AP-01, presenting a promising strategy for addressing the global LDPE pollution crisis. Graphical abstract