A clay-based formulation of the herbicide imazaquin containing exclusively the biologically active enantiomer

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.

Herbicidal weed management practices: History and future prospects of nanotechnology in an eco-friendly crop production system

Weed management is an important aspect of crop production, as weeds cause significant losses in terms of yield and quality. Various approaches to weed management are commonly practiced by crop growers. Due to limitations in other control methods, farmers often choose herbicides as a cost-effective, rapid and highly efficient weed control strategy. Although herbicides are highly effective on most weeds, they are not a complete solution for weed management because of the genetic diversity and evolving flexibility of weed communities. The excessive and indiscriminate use of herbicides and their dominance in weed control have triggered the rapid generation of herbicide-resistant weed species. Moreover, environmental losses of active ingredients in the herbicides cause serious damage to the environment and pose a serious threat to living organisms. Scientific advances have enabled nanotechnology to emerge as an innovation with real potential in modern agriculture, adding a new dimension in the preparation of controlled release formulations (CRF) of herbicides. Here the required amount of active ingredients is released over longer periods of time to obtain the desired biological efficacy whilst reducing the harmful effects of these chemicals. Various organic and inorganic carrier materials have been utilised in CRF and researchers have a wide range of options for the synthesis of eco-friendly carrier materials, especially those with less or no toxicity to living organisms. This manuscript addresses the history, progress, and consequences of herbicide application, and discusses potential ways to reduce eco-toxicity due to herbicide application, along with directions for future research areas using the benefits of nanotechnology.

An enantioselective study of the behavior of the herbicide ethofumesate in agricultural soils: Impact of the addition of organoclays and biochar

Chiral pesticides that are still commercialized and incorporated into the environment as racemic mixtures of enantiomers require evaluation of the enantioselectivity of their biological activity and environmental fate processes for a better prediction of their field efficacy and environmental risks. In this work, we successfully separated the enantiomers of the chiral herbicide ethofumesate (ETFM), determined their absolute configuration, and characterized their herbicidal activity as well as their adsorption, degradation, enantiomerization, and leaching in Mediterranean agricultural soils. While the herbicidal activity of R-ethofumesate to the sensitive species Portulaca grandiflora was greater than that of S-ethofumesate, the adsorption, degradation, and leaching of the herbicide showed negligible enantioselectivity and enantiomer interconversion did not occur in soils. The adsorption of both enantiomers showed a positive correlation with the soil organic carbon content (r = 0.856, P = 0.015), and their degradation in soils occurred slowly (DT50 > 60 days) and at similar rates independent of their application as individual enantiomers or as a racemic mixture of enantiomers. The addition of three highly adsorptive materials to a scarcely adsorptive soil increased the adsorption of the enantiomers of ETFM and delayed their degradation without affecting the non-enantioselective character of the processes. As a result of their high adsorption capacity, the materials were highly effective in reducing the leaching of both enantiomers of ETFM through soil columns. The results of this work indicate that the application of single-enantiomer ETFM formulations, based on a higher herbicidal activity or a lower toxicity to non-target organisms of the formulated enantiomer, would reduce considerable exposure risks associated with incorporating into the environment the less favorable enantiomer, as this would show long persistence and high leaching potential in soils similar to its optical isomer.

Soil modification with organic amendments and organo-clays: Effects on sorption, degradation, and bioactivity of the allelochemical scopoletin

We assessed the effect of three organic amendments and two organo-clays on sorption, persistence, and phytotoxicity of scopoletin, an allelochemical compound with potential as bioherbicide, in a Mediterranean alkaline soil. The aim was to elucidate whether the phytotoxicity of scopoletin could be expressed better in amended than unamended soil. The three organic amendments were fresh solid olive-mill waste (OMW), composted solid olive-mill waste (OMWc), and biochar (BC) prepared from OMWc. The two organo-clays were a commercial organo-montmorillonite (Cloi10) and lab-synthesized oleate-modified hydrotalcite (HT-OLE). The amendments enhanced sorption of scopoletin by the soil consistently with their individual affinities for the allelochemical: Cloi10 ≫ OMW > BC > OMWc > HT-OLE. The soil persistence of scopoletin increased significantly because of the addition of Cloi10, OMW, and BC. This increase was attributed to a combination of sorption, which protected the allelochemical from rapid biodegradation, and microbial activity changes. Although the inhibitory effect produced by the amendments themselves obscured the phytotoxicity of scopoletin to Lactuca sativa L. in soil treated with OMW and Cloi10, applying scopoletin to BC-amended soil led to a marked reduction in root length and aerial biomass of the emerged seedlings even though BC alone did not negatively affect these parameters. This inhibitory effect of scopoletin in BC-amended soil was in contrast to the negligible effect exerted by the allelochemical when applied to unamended soil. The results show that soils treated with suitable amendments, such as BC, might provide a scenario in which the herbicidal properties of 7-hydroxycoumarins could be better expressed.