This study was carried out to evaluate the interaction between terrestrial food crop plants and microplastics (MPs) with a focus on understanding their uptake, effects on growth, physiological, biochemical, and yield characteristics of two different cultivars of Solanum tuberosum L. i.e., Variety-1, Astrix (AL-4) and Variety-2, Harmes (WA-4). Polyethylene (PE), polystyrene (PS), and polypropylene (PP) spheres of size 5 mu m were applied to the soil at concentrations of 0 %, 1 %, and 5 %. Morphological parameters, including seed germination rate, shoot and root lengths, leaf area, and fresh and dry biomass of plants, got reduced significantly with the increase in MP concentration. PS MPs caused the most negative impact, particularly at 5 %, leading to the greatest decline in growth and Na, Mg, Zn, Cu, Ni, and Mn nutrient content. The highest DPPH scavenging activity was observed in the 5 % PS MPs treatment with approximately a 45.34 % increase from the control, indicating its potential to enhance antioxidant activity in response to stress caused by PS MPs. Both reducing and non-reducing sugar contents and total proteins were also decreased significantly. Vitamin C content exhibited a significant increase in response to MPs, with the highest levels recorded under 5 % PS MPs treatments. This suggests an adaptive antioxidant response to mitigate oxidative damage induced by MPs. SEM analysis revealed tissue infiltration of MP particles in shoots, leaves, and tubers of both varieties. Among MPs, PS had the most detrimental effects, followed by PP and PE, with higher concentrations increasing the negative impact.

Expansive clay soil is known to cause damage to pavements due to its volume fluctuations with changes in moisture content, a phenomenon observed globally in many countries. Implementing suitable stabilisation treatments is crucial for improving the mechanical and hydraulic properties of the expansive clay subgrade. While cement and lime have traditionally been widely used as soil stabilisers, there is a growing emphasis on sustainable engineering due to increased awareness of global warming. Seeking alternative green and sustainable materials for soil stabilisation is demanded now, and one such alternative is using ethylene-vinyl acetate (EVA) copolymer emulsion. However, the use of EVA copolymer emulsion for stabilising expansive clay has been relatively underexplored in existing studies. This study evaluates the feasibility of utilising EVA copolymer emulsion for stabilising expansive clay subgrade through comprehensive laboratory tests to assess the mechanical (compaction, unconfined compressive strength, California bearing ratio, resilient modulus, and direct shear), hydraulic (soil-water retention curve and swellshrinkage), and micro-chemical (thermogravimetric analyses and scanning electron microscopic) performance of the soil. The experimental results indicate that the inclusion of 1 % EVA copolymer emulsion into the expansive clay provided the highest mechanical properties, resulting in an increase in the unconfined compressive strength, soaked California bearing ratio, resilient modulus, and cohesion by 8.8 %, 177.8 %, 35.8 % and 19.4 %, respectively. Swell-shrinkage behaviour was also improved with the addition of EVA copolymer, with 1 % EVA copolymer presenting the lowest swell-shrinkage index of 3.19 %/pF (14 % decrease in shrink-swell potential compared to the untreated clay).

Greening immediately after etiolated- seedling's emergence from the soil is critical for plants to initiate their autotrophic life cycle through photosynthesis. The greening process relies on a complex transcriptional network that fine- tunes the biosynthesis of chlorophyll and prevents premature development of chloroplasts. In this study, we identified the Arabidopsis HOOKLESS1 (HLS1) as a key regulator of light- induced cotyledon greening. Our results demonstrated that HLS1 is essential for the proper expression of greening- related genes controlling chlorophyll biosynthesis and chloroplast development. Loss of HLS1 severely disrupts the Pchlide- to- Chlide transition and impairs reactive oxygen species (ROS) scavenging in etiolated seedlings upon light exposure, leading to catastrophic ROS burst and even photobleaching. Biochemical assays revealed that HLS1 is a histone acetyltransferase mediating the deposition of H3K9ac and H3K27ac marks at multiple greening- related genes, thereby promoting their transcriptional activation. Genetic analysis further confirmed that HLS1's promotive effect on the greening process is fully dependent on its histone acetyltransferase activity. Moreover, the loss of HLS1 also interrupts the promotive effect of ethylene signaling on the greening process by reducing the binding of ETHYLENE- INSENSITIVE 3 to the promoter region of POR genes, thus inhibiting the activation effect of ethylene signaling on the expression of PORs. Collectively, our study reveals that HLS1 acetylates histones to activate greening- related genes, optimizing chlorophyll biosynthesis and chloroplast development during dark- to- light transition in seedlings.

As emerging pollutants, microplastics (MPs) pose serious threats to the terrestrial ecosystems, and the long-term presence of aged MPs in soil results in toxic effects on plant growth. However, the phytotoxicity mechanisms of aged MPs remain unclear. To understand the toxic effects of aged MPs and the response mechanism of lettuce plants, we selected polyethylene (PE) and polypropylene (PP) (commonly found in soil), and then studied the effects of the two phytotoxins on the soil-plant system before and after aging of the MPs. We found that aging enhanced the toxicity of the MPs to the plants. Compared with the original MPs-treatment group, aged PE and PP particles reduced plant biomasses by 26.19%-28.44% and 25.58%-26.13%, respectively, potentially due to the effects of aged MPs on the rhizosphere soil, which further inhibited nutrient absorption in lettuce. The metabolic response of lettuce to MPs was also different. Aged PE significantly attenuated malic acid and proline concentrations in lettuce, and the reduction in these two products inhibited photosynthesis, energy metabolism, and cellular homeostasis, thereby aggravating the damage caused by aged PE. Aged PP principally affected the metabolic pathways of phenylalanine, tyrosine and tryptophan, which was postulated to be the reason why aging enhanced the phytotoxicity of PP. This study provides new insights into the assessment of the toxic effects of MPs, as well as the environmental behavior and ecological risks of aged MPs.

In this study, novel block copolymers consisting of poly(ethylene succinate) (PES) and poly(amino acid)s were synthesized, and their thermal and mechanical properties and biodegradability characteristics were investigated. Various types of poly(amino acid) units were successfully introduced using N-phenyloxycarbonyl amino acids (NPCs). The reactions between the terminally aminated PES and the NPCs were conducted by heating in N,N-dimethylacetamide at 65 degrees C. Structural analyses of the obtained polymers confirmed that the reaction with the NPCs proceeded from both ends of the terminally aminated PES. The results of material property measurements demonstrated that the melting point of the block copolymer containing poly(alanine) units increased beyond 200 degrees C while that of the original PES was similar to 100 degrees C. Additionally, its strain at break increased similar to 80-fold compared to that of PES with a similar molecular weight. The results of biodegradability tests using a soil suspension as an inoculum indicated that some of the block copolymers underwent biodegradation, and a correlation was observed between the biodegradability and the type and feed amount of NPC. Therefore, it was proposed that the degree, rate, and onset time of biodegradation could be controlled by altering the type and amount of incorporated poly(amino acid) units. This research may contribute to the optimal and facile synthesis of polyester-b-poly(amino acid) copolymers and to the expansion of the range of available biodegradable materials.

Nanoparticle contamination has been associated with adverse impacts on crop productivity. Thus, effective approaches are necessary to ameliorate NP-induced phytotoxicity. The present study aimed to investigate the efficacy of brassinosteroids and ethylene in regulating CuO NPs toxicity in rice seedlings. Therefore, we comprehensively evaluated the crosstalk of 24-Epibrassinolide and ethylene in regulating CuO NP-induced phytotoxicity at the physiological, cellular ultrastructural, and biochemical levels. The results of the study illustrated that exposure to CuO NPs at 450 mg/L displayed a significant decline in growth attributes and induced toxic effects in rice seedlings. Furthermore, the exogenous application of ethylene biosynthesis precursor 1-aminocyclopropane-1-carboxylic acid (ACC) at 20 mu M with 450 mg/L of CuO NPs significantly enhanced the reactive oxygen species (ROS) accumulation that led to the stimulation of ultrastructural and stomatal damage and reduced antioxidant enzyme activities (CAT and APX) in rice tissues. On the contrary, it was noticed that 24-Epibrassinolide (BR) at 0.01 mu M improved plant biomass and growth, restored cellular ultrastructure, and enhanced antioxidant enzyme activities (CAT and APX) under exposure to 450 mg/L of CuO NPs. In addition, brassinosteroids reduced ROS accumulation and the toxic effects of 450 mg/L of CuO NPs on guard cells and the stomatal aperture of rice seedlings. Interestingly, when 0.01 mu M of brassinosteroids, 20 mu M of ACC, and 450 mg/L of CuO NPs were applied together, BRs and ethylene showed antagonistic crosstalk under CuO NP stress via partially reducing the ethylene-induced CuO NP toxicity on plant growth, cellular ultrastructure, stomatal aperture, and guard cell and antioxidant enzyme activities (CAT and APX) in rice seedlings. BR supplementation with ACC and CuO NPs notably diminished ACC-induced CuO NPs' toxic effects on all of the mentioned attributes in rice seedlings. This study uncovered the interesting crosstalk of two main phytohormones under CuO NPs stress, providing basic knowledge to improve crop yield and productivity in CuO NPs-contaminated areas.

Traditional soil stabilization methods, including cement and chemical grouting, are energy-intensive and environmentally harmful. Microbial-induced carbonate precipitation (MICP) technology offers a sustainable alternative by utilizing microorganisms to precipitate calcium carbonate, binding soil particles to improve mechanical properties. However, the application of MICP technology in soil stabilization still faces certain challenges. First, the mineralization efficiency of microorganisms needs to be improved to optimize the uniformity and stability of carbonate precipitation, thereby enhancing the effectiveness of soil stabilization. Second, MICP-treated soil generally exhibits high fracture brittleness, which may limit its practical engineering applications. Therefore, improving microbial mineralization efficiency and enhancing the ductility and overall integrity of stabilized soil remain key issues that need to be addressed for the broader application of MICP technology. This study addresses these challenges by optimizing microbial culture conditions and incorporating polyethylene fiber reinforcement. The experiments utilized sandy soil and polyethylene fibers, with Bacillus pasteurii as the microbial strain. The overall experimental process included microbial cultivation, specimen solidification, and performance testing. Optimization experiments for microbial culture conditions indicated that the optimal urea concentration was 0.5 mol/L and the optimal pH was 9, significantly enhancing microbial growth and urease activity, thereby improving calcium carbonate production efficiency. Specimens with different fiber contents (0% to 1%) were prepared using a stepwise intermittent grouting technique to form cylindrical samples. Performance test results indicated that at a fiber content of 0.6%, the unconfined compressive strength (UCS) increased by 80%, while at a fiber content of 0.4%, the permeability coefficient reached its minimum value (5.83 x 10-5 cm/s). Furthermore, microscopic analyses, including X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), revealed the synergistic effect between calcite precipitation and fiber reinforcement. The combined use of MICP and fiber reinforcement presents an eco-friendly and efficient strategy for soil stabilization, with significant potential for geotechnical engineering applications.

An emerging alternative to improve the mechanical properties of fine soils susceptible to cracking is the addition of fibers obtained from reused synthetic materials such as polyethylene terephthalate (PET). The technical literature on the fracture mechanics of PET fiber-reinforced soils is rather scarce, so there has been insufficient progress in determining fracture parameters and standardized procedures to find optimal reinforcement conditions. This research uses experimental techniques to induce tensile stresses in clayey silty soil samples from the Valley of Mexico reinforced with different fiber contents. By applying approaches based on linear elastic and elastoplastic theory, parameters useful for the study of fracture mechanics and flexural strength of PET- reinforced soil were estimated: tensile strength, critical energy release rate, critical stress intensity factor, and contour integral for crack propagation under plasticity. In addition, imaging techniques are used to measure the deformations generated in bending tests of reinforced soil beams and to study crack propagation from initiation to maximum stresses. The addition of PET fibers significantly improved soil response by reducing cracking, increasing tensile strength, and providing ductile behavior as cracking progressed. These effects indicate the great potential of recycled PET fibers as a subgrade improvement method for soft, cracking soil deposits, or even for earthworks and slope stabilization in clayey soils on road projects.

PurposeThe present work aims to prepare biocomposites blend based on linear low density polyethylene/ starch without using harmful chemicals to improve the adhesion between two phases. Also, the efficiency of essential oils as green plasticizers and natural antimicrobial agents were evaluated.Design/methodology/approachBarrier properties and biodegradation behavior of linear low density polyethylene/starch (LLDPE/starch) blends plasticized with different essential oils including moringa oleifera and castor oils wereassessed as a comparison with traditional plasticizer such as glycerol. Biodegradation behavior forLLDPE/starch blends was monitored by soil burial test. The composted samples were recovered then washed followed by drying, and weighting samples after 30, 60, and 90 days to assess the change in weight loss. Also, mechanical properties including retention values of tensile strength and elongation at break were measured before and after composting. Furthermore, scanning electron microscope (SEM) was used to evaluate the change in the morphology of the polymeric blends. In addition to, the antimicrobial activity of plasticized LLDPE/starch blends films was evaluated using a standard plate counting technique.FindingsThe results illustrate that the water vapor transition rate increases from 2.5 g m-2 24 h-1 for LLDPE/5starch to 4.21 g m-2 24 h-1 and 4.43 g m-2 24 h-1 for castor and moringa oleifera respectively. Also, the retained tensile strength values of all blends decrease gradually with increasing composting period. Unplasticized LLDPE/5starch showed highest tensile strength retention of 91.6% compared to the other blends that were 89.61, 88.49 and 86.91 for the plasticized LLDPE/5starch with glycerol, castor and M. oleifera oils respectively. As well as, the presence of essential oils in LLDPE/ starch blends increase the inhibition growth of escherichia coli, candida albicans and staphylococcus aureus.Originality/valueThe objective of this work is to develop cost-effective and environmentally-friendly methods for preparing biodegradable polymers suitable for packaging applications.

Hydrogel is a three-dimensional polymer that can absorb large amounts of reagents while maintaining structural integrity. This material has been applied in many fields especially in smart agriculture. To improve the economic viability, the reusability of hydrogels in agricultural engineering over multiple cycles of adsorption and desorption is an urgent requirement. This can be solved if the crosslinker is used properly. Therefore, in this work, a series of porous semi-interpenetrating polymer network (IPN) hydrogels based on linear polyacrylamide, acrylamide, maleic acid, and N,N'-methylenebisacrylamide (MBA) were synthesized. The hydrogels were evaluated for the impact of MBA content on the characteristics and applicability as a urea fertilizer carrier. The chemical composition, morphology, mechanical, and rheological properties, swelling behavior, urea absorption, and desorption of hydrogels with crosslinker content in the range of 0.5%-2.0% were investigated. The porous structure was confirmed by scanning electron microscopy images. Changing the MBA content significantly affected all characteristics of the hydrogels. In particular, increasing the MBA content decreased the equilibrium swelling ratios in all investigated environments. The maximum amount of urea loaded into the hydrogel was also reduced from 435.88 to 188.50 mg/g. This increase also changed the swelling mechanism from non-Fickian to Fickian, whereas the urea release mechanism changed from Fickian to non-Fickian. Finally, the hydrogels demonstrated stability in soil over multiple cycles of water absorption and release. This study provides valuable insights into designing a semi-IPN hydrogel with desired properties that meet the application requirements of modern farming techniques.