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It is crucial to clarify how the iron nanostructure activates plant growth, particularly in combination with arbuscular mycorrhizal fungi (AMF). We first identified 1.0 g·kg-1 of nanoscale zerovalent iron (nZVI) as appropriate dosage to maximize maize growth by 12.7-19.7% in non-AMF and 18.9-26.4% in AMF, respectively. Yet, excessive nZVI at 2.0 g·kg-1 exerted inhibitory effects while FeSO4 showed slight effects (p > 0.05). Under an appropriate dose, a nano core-shell structure was formed and the transfer and diffusion of electrons between PS II and PS I were facilitated, significantly promoting the reduction of ferricyanide and NADP (p < 0.05). SEM images showed that excessive nZVI particles can form stacked layers on the surface of roots and hyphae, inhibiting water and nutrient uptake. TEM observations showed that excessive nanoparticles can penetrate into root cortical cells, disrupt cellular homeostasis, and substantially elevate Fe content in roots (p < 0.05). This exacerbated membrane lipid peroxidation and osmotic regulation, accordingly restricting photosynthetic capacity and AMF colonization. Yet, appropriate nZVI can be adhered to a mycelium surface, forming a uniform nanofilm structure. The strength of the mycelium network was evidently enhanced, under an increased root colonization rate and an extramatrical hyphal length (p < 0.05). Enhanced mycorrhizal infection was tightly associated with higher gas exchange and Rubisco and Rubisco enzyme activities. This enabled more photosynthetic carbon to input into AMF symbiont. There existed a positive feedback loop connecting downward transfer of photosynthate and upward transport of water/nutrients. FeSO4 only slightly affected mycorrhizal development. Thus, it was the Fe nanostructure but not its inorganic salt state that primed AMF symbionts for better growth.
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Physio-biochemical regulations governing crop growth period are pivotal for drought adaptation. Yet, the extent to which functionality of arbuscular mycorrhizal fungi (AM fungi) varies across different stages of maize growth under drought conditions remains uncertain. Therefore, periodic functionality of two different AM fungi i.e., Rhizophagus irregularis SUN16 and Glomus monosporum WUM11 were assessed at jointing, silking, and pre-harvest stages of maize subjected to different soil moisture gradients i.e., well-watered (80% SMC (soil moisture contents)), moderate drought (60% SMC), and severe drought (40% SMC). The study found that AM fungi significantly (p < 0.05) affected various morpho-physiological and biochemical parameters at different growth stages of maize under drought. As the plants matured, AM fungi enhanced root colonization, glomalin contents, and microbial biomass, leading to increased nutrient uptake and antioxidant activity. This boosted AM fungal activity ultimately improved photosynthetic efficiency, evident in increased photosynthetic pigments and photosynthesis. Notably, R. irregularis and G. monosporum improved water use efficiency and mycorrhizal dependency at critical growth stages like silking and pre-harvest, indicating their potential for drought resilience to stabilize yield. The principal component analysis highlighted distinct plant responses to drought across growth stages and AM fungi, emphasizing the importance of early-stage sensitivity. These findings underscore the potential of incorporating AM fungi into agricultural management practices to enhance physiological and biochemical responses, ultimately improving drought tolerance and yield in dryland maize cultivation.
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Secas , Micorrizas , Zea mays , Zea mays/microbiologia , Zea mays/crescimento & desenvolvimento , Zea mays/metabolismo , Micorrizas/fisiologia , Fotossíntese , Raízes de Plantas/microbiologia , Raízes de Plantas/crescimento & desenvolvimento , Glomeromycota/fisiologia , Glomeromycota/crescimento & desenvolvimento , Água/metabolismo , Biomassa , FungosRESUMO
Non-hydraulic root source signaling (nHRS) is a unique positive response to soil drying in the regulation of plant growth and development. However, it is unclear how the nHRS mediates the tradeoff between source and sink at the late growth stages and its adaptive mechanisms in primitive wheat. To address this issue, a root-splitting design was made by inserting solid partition in the middle of the pot culture to induce the occurrence of nHRS using four wheat cultivars (MO1 and MO4, diploid; DM22 and DM31, tetraploid) as materials. Three water treatments were designed as 1) both halves watered (CK), 2) holistic root system watered then droughted (FS), 3) one-half of the root system watered and half droughted (PS). FS and PS were designed to compare the role of the full root system and split root system to induce nHRS. Leaves samples were collected during booting and anthesis to compare the role of nHRS at both growth stages. The data indicated that under PS treatment, ABA concentration was significantly higher than FS and CK, demonstrating the induction of nHRS in split root design and nHRS decreased cytokinin (ZR) levels, particularly in the PS treatment. Soluble sugar and proline accumulation were higher in the anthesis stage as compared to the booting stage. POD activity was higher at anthesis, while CAT was higher at the booting stage. Increased ABA (nHRS) correlated with source-sink relationships and metabolic rate (i.e., leaf) connecting other stress signals. Biomass density showed superior resource acquisition and utilization capabilities in both FS and PS treatment as compared to CK in all plants. Our findings indicate that nHRS-induced alterations in phytohormones and their effect on source-sink relations were allied with the growth stages in primitive wheat.
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Diploide , Raízes de Plantas , Transdução de Sinais , Tetraploidia , Triticum , Triticum/genética , Triticum/crescimento & desenvolvimento , Triticum/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Raízes de Plantas/genética , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Brotos de Planta/genética , Reguladores de Crescimento de Plantas/metabolismo , Ácido Abscísico/metabolismo , Citocininas/metabolismo , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Folhas de Planta/genéticaRESUMO
Arbuscular mycorrhizal fungi (AMF) establish symbiotic relationships with roots of most plants, contributing to plant water uptake and soil carbon (C) sequestration. However, the interactive contribution and of long-term field AMF inoculation and water conservation on maize yield and soil organic carbon (SOC) sequestration in drylands remain largely unknown. After 7-year long-term field inoculation with AMF Funneliformis mosseae, AMF suppression by fungicide benomyl, and no-AMF/no-benomyl control, and two water conservation practices of half-film and full-film mulching (â¼50 % and â¼100 crop planted area covered with plastic film), this study thus applied in situ 13CO2-C labeling and high-throughput sequencing to quantify newly photosynthetically assimilated C into different soil C pools including soil aggregates and respiration, and their effects on maize growth and productivity. Results showed that 7-year long-term AMF inoculation significantly increased the relative abundance of F. mosseae in rhizosphere soil and root AMF colonization, indicating that F. mosseae successfully dominated in AMF communities. Compared to no-AMF/no-benomyl control, AMF colonization significantly increased shoot biomass and maize yield by 17.9 % and 20.3 % while mitigated the less water conservation effects of half-film mulching on maize performance. The SOC content under field AMF inoculation SOC was increased from 7.9 to 8.4 g kg-1 and also the mean weight diameter of aggregates (1.21 to 1.35), e.g. aggregate stability. After 1 and/or 40 days 13C labeling, the enhanced 13C translocations into macro-aggregates with decreased 13C emissions from microbial decomposition under field AMF inoculation had contributed to SOC conservation in bulk soil. These results suggest that AMF inoculation in dryland crops is promising to increase crop yield while promoting more atmospheric CO2 fixation in soil aggregates. A long-term field AMF inoculation will enhance our understanding of applying beneficial mycorrhizal fungi to enhance soil C sequestration and also crop yield via plant-fixed atmospheric CO2 in semi-arid and arid farmlands.
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Carbono , Micorrizas , Solo , Zea mays , Zea mays/microbiologia , Micorrizas/fisiologia , Solo/química , Carbono/metabolismo , Microbiologia do Solo , Glomeromycota/fisiologia , Isótopos de Carbono , Sequestro de Carbono , Raízes de Plantas/microbiologiaRESUMO
Plastic fragments are widely found in the soil profile of terrestrial ecosystems, forming plastic footprint and posing increasing threat to soil functionality and carbon (C) footprint. It is unclear how plastic footprint affects C cycling, and in particularly permanent C sequestration. Integrated field observations (including 13C labelling) were made using polyethylene and polylactic acid plastic fragments (low-, medium- and high-concentrations as intensifying footprint) landfilling in soil, to track C flow along soil-plant-atmosphere continuum (SPAC). The result indicated that increased plastic fragments substantially reduced photosynthetic C assimilation (p < 0.05), regardless of fragment degradability. Besides reducing C sink strength, relative intensity of C emission increased significantly, displaying elevated C source. Moreover, root C fixation declined significantly from 21.95 to 19.2 mg m-2, and simultaneously root length density, root weight density, specific root length and root diameter and surface area were clearly reduced. Similar trends were observed in the two types of plastic fragments (p > 0.05). Particularly, soil aggregate stability was significantly lowered as affected by plastic fragments, which accelerated the decomposition rate of newly sequestered C (p < 0.05). More importantly, net C rhizodeposition declined averagely from 39.77 to 29.41 mg m-2, which directly led to significant decline of permanent C sequestration in soil. Therefore, increasing plastic footprint considerably worsened C footprint regardless of polythene and biodegradable fragments. The findings unveiled the serious effects of plastic residues on permanent C sequestration across SPAC, implying that current C assessment methods clearly overlook plastic footprint and their global impact effects.
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Pegada de Carbono , Plásticos , Solo , Solo/química , Carbono/análise , Atmosfera/química , Ciclo do Carbono , Ecossistema , Plantas , Sequestro de Carbono , Monitoramento Ambiental/métodosRESUMO
It is crucial to clarify the physiological responses of wheat (T. aestivum) plants to source-sink manipulation and assimilation transportation under drought stress during domestication of dryland wheat. In this research, a two-year field experiment was conducted using nine wheat cultivars in a semiarid site of northwest China. The source-sink manipulation treatments including defoliation of flag leaves and 50% removal of ears were applied at the anthesis stage under two levels of drought stress conditions i.e. progressive water supply (PWS) and rainfed drought treatment (RDT). Our results indicated that drought stress reduced the dry weight of leaves, sheaths and stems, as well as caused a significant yield reduction. High ploidy wheat exhibits a greater capacity to sustain higher grain yields when subjected to drought stress, primarily due to its stronger buffer capacity between source supply and sink demand. All wheat species with different ploidy levels had a certain degree of source limitation and sink restriction. During the domestication of wheat, the type of source and sink might be ploidy-dependent with progressive water deficit, but similar interactive relationships. The source-sink ratio of tetraploid species was the largest, while that of hexaploid species was the lowest.
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Triticum , Água , Triticum/genética , Domesticação , Grão Comestível , Folhas de Planta/fisiologiaRESUMO
Drought is a potent abiotic stressor that arrests crop growth, significantly affecting crop health and yields. The arbuscular mycorrhizal fungi (AMF), and plant growth-promoting rhizobacteria (PGPR) can offer to protect plants from stressful environments through improving water, and nutrient use efficiency by strengthening plant root structure and harnessing favorable rhizosphere environments. When Acaulospora laevis (AMF) and Bacillus subtilus (PGPR) are introduced in combination, enhanced root growth and beneficial microbial colonization can mitigate drought stress. To assess this potential, a pot experiment was done with maize (Zea mays L.) to explore the effects of A. laevis and B. subtilus under different water levels (well-watered = 80 %; moderate water stress = 55 %; and severe water stress = 35 %) on maize yield, soil microbial activities, nutrients contents, root, and leaf functioning. Plants exposed to severe drought stress hampered their root and leaf functioning, and reduced grain yield compared with control plants. Combined use of AMF and PGPR increased root colonization (104.6 %-113.2 %) and microbial biomass carbon (36.38 %-40.23 %) under moderate to severe drought conditions over control. Higher root colonization was strongly linked with elevated ACC (aminocyclopropane-1-carboxylic acid) production, subsequently enhancing water use efficiency (21.62 %-12.77 %), root hydraulic conductivity (1.9 %-1.4 %) and root nutrient uptake under moderate to severe drought conditions. Enhanced nutrient uptake further promoted leaf photosynthetic rate by 27.3 %-29.8 % under moderate and severe drought stress. Improving leaf and root physiological functioning enhanced maize grain yield under stressful environments. Furthermore, co-inoculation with AMF-PGPR reduced cellular damage by lowering oxidative enzyme levels and increasing antioxidative enzyme activities, improving plant performance and grain yield under stressful environments. Conclusively, the synergistic interaction of AMF with PGPR ensured plant stress tolerance by reducing cellular injury, facilitating root-leaf functioning, enhancing nutrient-water-use-efficiencies, and increasing yield under drought stress.
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Micorrizas , Micorrizas/fisiologia , Zea mays , Solo , Raízes de Plantas/microbiologia , Retroalimentação , DesidrataçãoRESUMO
Polyethylene film mulching is a key technology for soil water retention in dryland agriculture, but the aging of the films can generate a large number of microplastics with different shapes. There exists a widespread misunderstanding that the concentrations of microplastics might be the determinant affecting the diversity and assembly of soil bacterial communities, rather than their shapes. Here, we examined the variations of soil bacteria community composition and functioning under two-year field incubation by four shapes (ball, fiber, fragment and powder) of microplastics along the concentration gradients (0.01%, 0.1% and 1%). Data showed that specific surface area of microplastics was significantly positively correlated with the variations of bacterial community abundance and diversity (r=0.505, p<0.05). The fragment- and fiber-shape microplastics displayed more pronounced interfacial continuity with soil particles and induced greater soil bacterial α-diversity, relative to the powder- and ball-shape ones. Strikingly, microplastic concentrations were not significantly correlated with bacterial community indices (r=0.079, p>0.05). Based on the variations of the ßNTI, bacterial community assembly actually followed both stochastic and deterministic processes, and microplastic shapes significantly modified soil biogeochemical cycle and ecological functions. Therefore, the shapes of microplastics, rather than the concentration, significantly affected soil bacterial community assembly, in association with microplastic-soil-water interfaces.
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Physical thickness of low-density polyethylene (LDPE) films might determine the release rate of phthalic acid esters (PAEs) & structural integrity and affect production efficiency. However, this critical issue is still unclear and little reported. Aging effects were evaluated in LDPE films with the thickness of 0.006, 0.008, 0.010 and 0.015 mm in a maize field of irrigation region. The Scanning electron microscope (SEM) results showed that the proportion of damaged area (Dam) to total area of LDPE films was massively lowered with increasing thickness after aging. The highest and lowest Dam was 32.2% and 3.5% in 0.006 and 0.015 mm films respectively. Also, the variations in peak intensity of asymmetric & symmetrical stretching vibrations (ASVI & SSVI) were detected using Fourier transform infrared spectrum (FTIR), indicating that the declines in peak intensity tended to be slower with thickness. Interestingly, the declines in physical integrity were tightly associated with increasing exhalation rate of PAEs. Average releasing rate of PAEs was 38.2%, 31.4%, 31.5% and 19.7% in LDPE films from 0.006 to 0.015 mm respectively. Critically, thicker film mulching can lead to greater soil water storage at plough layer (SWS-PL) and better thermal status, accordingly harvesting higher economic benefit. Therefore, LDPE film thickening may be a solution to reduce environmental risk but improve production efficiency in arid region.
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Luz , Polietileno , Solo , VibraçãoRESUMO
This study aims to address the lack of relevant researches in the field of waste recycling using the Theory of Planned Behavior (TPB). A village-scale social survey was conducted to investigate the degree of farmers' participation in a waste plastic film program, i.e. Old for New in northwest China. The program required farmers to recycle plastic film residues in exchange for new films. Survey results showed that 67.5% of farmers accepted the program, yet only 14.5% of them actually participated. Logistic regression analysis was used to analyze questionnaire data and identify the factors that significantly affected farmers' recycling behavior. Principal component and weight analysis further showed that farmers' participation was mainly influenced by their attitudes (p < 0.01), with a relative weight (RW) of 46.3%. Yet, subjective norms (p < 0.1) and perceived behavior control (p < 0.1) had less effect on the degree of participation, and their RWs were 4.2% and 4.1% only, respectively. Moreover, the RW of plastic film usage characteristics and household characteristics reached up to 13.2% and 6.4%, respectively. Interestingly, environmental awareness (ß = 0.083) and compulsory environmental education (ß = 0.130) as surface factors strongly affected the farmers' adoption and response, with the RW of 25.7%. As such, the extended TPB model was established to analyze the participation behavior of farmers for stronger explanatory power. This study highlighted a promising strategy based on TPB for waste plastic film recycling and similar environmental management practices.
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Fazendeiros , Teoria do Comportamento Planejado , Humanos , Agricultura , China , PlásticosRESUMO
The polyethylene (PE) film mulching as a water conservation technology has been widely used in dryland agriculture, yet the long-term mulching has led to increasing accumulation of secondary pollutants in soils. The decomposition of PE film-sourced pollutants is directly associated with the enrichment of specific bacterial communities. We therefore hypothesized that plant biomass may act as an organic media to mediate the pollutant decomposition via reshaping bacterial communities. To validate this hypothesis, plant biomass (dried maize straw and living clover) was embedded at the underlying surface of PE film, to track the changes in the composition and function of bacterial communities in maize field across two years. The results indicated that both dry crop straw and alive clover massively promoted the α-diversity and abundance of dominant bacteria at plastisphere, relative to bulk soil. Bacterial communities tended to be clustered at plastisphere, forming the bacteria islands to enrich pollutant-degrading bacteria, such as Sphingobacterium, Arthrobacter and Paracoccus. As such, plastisphere bacteria islands substantially enhanced the degradation potential of chloroalkene and benzoate (p < 0.05). Simultaneously, bacterial network became stabilized and congregated at plastisphere, and markedly improved the abundance of plastisphere module hubs and connectors bacteria via stochastic process. Particularly, bacterial community composition and plastic film-sourced pollutants metabolism were evidently affected by soil pH, carbon and nitrogen sources that were mainly derived from the embedded biomass. To sum up, plant biomass embedding as a nature-based strategy (NbS) can positively mediate the decomposition of plastic-sourced pollutants through plastisphere bacteria island effects.
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Poluentes Ambientais , Solo , Solo/química , Biomassa , Polietileno , Água/análise , Agricultura/métodos , Plásticos , Bactérias , Microbiologia do SoloRESUMO
The rise of plasticulture as mulching material in farming systems has raised concerns about microplastics (MPs) in the agricultural landscape. MPs are emerging pollutants in croplands and water systems with significant ecological risks, particularly over the long term. In the soil systems, MPs polymer type, thinness, shape, and size induces numerous effects on soil aggregates, dissolved organic carbon (C), rapidly oxidized organic C, microbial biomass C, microbial biomass nitrogen (N), microbial immobilization, degradation of organic matter, N cycling, and production of greenhouse gas emissions (GHGs), thereby posing a significant risk of impairing soil physical and biochemical properties over time. Further, toxic chemicals released from polyethylene mulching (PMs) might indirectly harm plant growth by affecting soil wetting-drying cycles, releasing toxic substances that interact with soil matrix, and suppressing soil microbial activity. In the environment, accumulation of MPs poses a risk to human health by accelerating emissions of GHGs, e.g., methane and carbon dioxide, or directly releasing toxic substances such as phthalic acid esters (PAEs) into the soils. Also, larger sizes MPs can adhere to root surface and block stomata could significantly change the shape of root epidermal cells resulting in arrest plant growth and development by restricting water-nutrient uptake, and gene expression and altering the biodiversity of the soil pollutants. In this review, we systematically analyzed the potential risks of MPs to the soil-plant and human body, their occurrence, abundance, and migration in agroecosystems. Further, the impacts of MPs on soil microbial function, nutrient cycling, soil C, and GHGs are mechanistically reviewed, with emphasis on potential green solutions such as organic materials amendments along with future research directions for more eco-friendly and sustainable plastic management in agroecosystems.
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Poluentes Ambientais , Microplásticos , Humanos , Microplásticos/toxicidade , Plásticos , Solo/química , Agricultura , EcossistemaRESUMO
The primary utilization strategy for meadow grasslands on the Qinghai-Tibet Plateau (QTP) is livestock grazing. This practice is considered as one of the major drivers of plant-associated bacterial community construction and changes in soil properties. The species of Kobresia humilis is considered as the most dominant one in grasslands. However, how different grazing practices affect the phyllosphere and rhizosphere bacterial communities of K. humilis is unknown. To address this issue, the effects of the grazing enclosure (GE), single-species grazing (YG and SG, representing yak only and sheep only, respectively), and different ratios of grazing (ratio of yak to sheep is 1:2, 1:4, and 1:6, represented by MG1:2, MG1:4, and MG1:6, respectively) on the dominant plant of K. humilis, it's phyllosphere and rhizosphere bacteria, and soil properties were investigated using artificially controlled grazing and grazing enclosure. Our data showed that grazing enclosure enhanced vegetation coverage, and rhizosphere bacterial richness and diversity, while reduced plant number and bacterial network stability of K. humilis. The NO3--N, K+, and Cl- concentrations were lower under grazing compared to GE. SG reduced the concentration of NH4+-N, TN, K+, and Na+ compared to YG. Moderate grazing intensity had a lower relative abundance of the r-strategists (Bacteroidota and Gammaproteobacteria) with higher bacterial network stability. Yak and sheep grazing showed reversed impacts on the bacterial network stability between the phyllosphere and rhizosphere of K. humilis. Proteobacteria and Actinobacteriota were identified in the molecular ecological network analysis as keystone taxa in the phyllosphere and rhizosphere networks, respectively, under all treatments. This study explained why sheep grazing has more adverse effects on grazing-tolerant grass species, K. humilis, than yak grazing, and will contribute to a better understanding of the impacts of different grazing practices and grazing enclosure on alpine grassland ecosystems on the QTP.
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Carex (Planta) , Ecossistema , Animais , Ovinos , Pradaria , Rizosfera , Tibet , Bactérias , SoloRESUMO
Leaf photosynthetic nitrogen-use efficiency (PNUE) diversified significantly among C3 species. To date, the morpho-physiological mechanisms and interrelationships shaping PNUE on an evolutionary time scale remain unclear. In this study, we assembled a comprehensive matrix of leaf morpho-anatomical and physiological traits for 679 C3 species, ranging from bryophytes to angiosperms, to comprehend the complexity of interrelationships underpinning PNUE variations. We discovered that leaf mass per area (LMA), mesophyll cell wall thickness (Tcwm ), Rubisco N allocation fraction (PR ), and mesophyll conductance (gm ) together explained 83% of PNUE variations, with PR and gm accounting for 65% of those variations. However, the PR effects were species-dependent on gm , meaning the contribution of PR on PNUE was substantially significant in high-gm species compared to low-gm species. Standard major axis (SMA) and path analyses revealed a weak correlation between PNUE and LMA (r2 = 0.1), while the SMA correlation for PNUE-Tcwm was robust (r2 = 0.61). PR was inversely related to Tcwm , paralleling the relationship between gm and Tcwm , resulting in the internal CO2 drawdown being only weakly proportional to Tcwm . The coordination of PR and gm in relation to Tcwm constrains PNUE during the course of evolution.
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Nitrogênio , Folhas de Planta , Folhas de Planta/fisiologia , Plantas , Fotossíntese/fisiologia , Células do Mesofilo/fisiologia , Parede Celular , Dióxido de CarbonoRESUMO
We investigated the priming effect of nanoscale zero-valent iron (nZVI) on carbon sink and iron uptake, and the possible mediation by AMF (arbuscular mycorrhizal fungi, Funneliformis mosseae) in semiarid agricultural soils. Maize seed dressings comprised of three nZVI concentrations of 0, 1, 2 g·kg-1 and was tested with and without AMF inoculation under high and low soil moistures, respectively. The ICP-OES observations indicated that both low dose of nZVI (1 g·kg-1) and high dose of nZVI (2 g·kg-1) significantly increased the iron concentrations in roots (L: 54.5-109.8 %; H: 119.1-245.4 %) and shoots (L: 40.8-78.9 %; H: 81.1-99.4 %). Importantly, the absorption and translocation rate of iron were substantially improved by AMF inoculation under the low-dose nZVI. Yet, the excess nanoparticles as a stress were efficiently relieved by rhizosphere hyphae, and the iron concentration in leaves and stems can maintain as high as about 300 mg·kg-1 while the iron translocation efficiency was reduced. Moreover, next-generation sequencing confirmed that appropriate amount of nZVI clearly improved the rhizosphere colonization of Funneliformis mosseae (p < 0.001) and the development of soil fungal community. Soil observations further showed that the hyphae development and GRSP (glomalin-related soil protein) secretion were significantly promoted (p < 0.05), with the increased R0.25 (< 0.25 mm) by 35.97-41.16 %. As a return, AMF and host plant turned to input more organic matter into soils for microbial growth and Fe uptake, and such interactions became more pronounced under drought stress. In contrast, high dose of nZVI (2 g·kg-1) tended to agglomerate on the surface of hyphae and spores, causing severe deformation and inactivation of AMF symbionts. Therefore, the priming effects of nZVI on carbon sequestration and Fe uptake in agricultural soils were positively mediated by AMF via the feedback loop of the plant-soil-microbe system for enhanced adaptation to global climate change.
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Ferro , Micorrizas , Ferro/metabolismo , Solo , Sequestro de Carbono , Micorrizas/fisiologia , Raízes de PlantasRESUMO
Plastic film residuals are increasingly remaining in cultivated lands. However, it is a critical issue how residual plastic type and thickness affect soil properties and crop yield. To address this issue, in situ landfill was conducted using thick polyethylene (PEt1), thin polyethylene (PEt2), thick biodegradable (BIOt1), thin biodegradable (BIOt2) residues, and CK (control) with no residues landfill in a semiarid maize field. The findings demonstrated that the impact of various treatments on soil characteristics and maize yield varied considerably. Soil water content decreased by 24.82% in PEt1 and 25.43% in PEt2, compared to BIOt1 and BIOt2, respectively. BIOt2 treatment increased soil bulk density by 1.31 g cm-3 and lowered soil porosity by 51.11%, respectively; it also elevated the silt/clay proportion by 49.42% relative to CK. In contrast, microaggregate composition in PEt2 was higher (43.02%). Moreover, BIOt2 lowered soil nitrate (NO3-) and ammonium (NH4+) content. Compared with other treatments, BIOt2 resulted in significantly higher soil total nitrogen (STN) and lower SOC/STN. Finally, BIOt2 exhibited the lowest water use efficiency (WUE) (20.57 kg ha-1 mm-1) and yield (6896 kg ha-1) among all the treatments. Therefore, BIO film residues exhibited detrimental impacts on soil quality and maize productivity compared to PE film ones. Considering film thickness, thin residual films more evidently influenced soil quality and maize productivity than thick film ones.
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Solo , Zea mays , Solo/química , Agricultura/métodos , Polietileno , Plásticos , Água/análise , Nitrogênio/análise , ChinaRESUMO
It is crucial to elucidate the release rate of microplastics (MPs) and phthalic acid esters (PAEs) in agricultural soil and their effects on crop productivity regarding film types and thicknesses. To address this issue, two-year landfill test was performed using 0.016 mm-thick polyethylene (PEt1) & biodegradable (BIOt1), and 0.01 mm-thin polyethylene (PEt2) & biodegradable (BIOt2) residual films as materials with no landfill as CK. Scanning electron microscopy (SEM) and infrared analyses revealed that two-year landfill caused considerable changes in physical forms and spectral peaks in BIO film, which was more pronounced in thin BIO (36.90 % weight loss). Yet, less changes were presented in the above analyzes in polyethylene (PE) films, and thick films damaged relatively less. MPs number was 86,829.11 n/kg in BIOt1 and 134,912.27 n/kg in BIOt2, equivalent to 2.55 and 3.72 times higher than in PEt1 and PEt2, respectively. This was closely associated with PAEs release, as soil PAEs concentration was substantially lower in PEt1 (17.60 g/kg) and PEt2 (21.43 g/kg) than in BIOt1 and BIOt2 (37.12 g/kg and 49.20 g/kg), respectively. Furthermore, maize productivity parameters were negatively correlated with the amount of MPs and PAEs. BIOt2 and PEt1 had the lowest and highest grain yield, respectively. BIO exhibited greater environmental risk and adverse effects on soil and crop productivity than PE film due to physical degradation and release of PAEs. Thickness-wise comparison exhibited that thin film residues had more adverse effect relative to thick film ones.
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Ácidos Ftálicos , Poluentes do Solo , Solo/química , Microplásticos/toxicidade , Plásticos/química , Polietileno/análise , Poluentes do Solo/análise , Ácidos Ftálicos/análise , Ésteres/análise , ChinaRESUMO
We investigated a nature-based solution (NbS) via incorporating biocrust into alfalfa-maize intercropping system to test carbon sequestration in seriously eroded agricultural soils. Field investigation showed that the NbS (moss-dominated biocrust + intercropping) massively lowered surface soil erosion by 94.5% and soil carbon (C) and nitrogen (N) loss by 94.7 and 96.8% respectively, while promoting rainwater interception by 82.2% relative to bare land (CK). There generally existed positive interactions between biocrust and cropping in the integrated standing biodiversity system. Enhanced plant biomass input into soils substantially promoted soil fungal community diversity and abundance under NbS (p < 0.05). This enabled NbS to evidently improve soil macroaggregate proportion and mean weight diameter. Critically, topsoil carbon storage was increased by 2.5 and 10.7%, compared with CK and pure intercropping (p < 0.05). Conclusively, the standing diversity under such NbS fostered soil C sequestration via water interception and plant-soil-microbe interactions in degraded agricultural soils.
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Melatonin, a plant/animal origin hormone, regulates plant response to abiotic stresses by protecting them from oxidative damage. This study identified physiochemical and molecular mechanism of melatonin-induced cadmium (Cd) stress tolerance and detoxification in cotton seedlings. Cotton seedlings, with or without melatonin (15 µM) pretreatment, were subjected to Cd (100 µM) stress in a hydroponic medium for eight days. We found that higher cellular Cd accumulation in leaf tissues significantly inhibited the growth and physiology of cotton seedlings. In contrast, melatonin-treated seedlings maintained leaf photosynthetic capacity, producing relatively higher fresh (17.4%) and dry (19.3%) weights than non-melatonin-treated plants under Cd-contaminated environments. The improved growth and leaf functioning were strongly linked with the melatonin-induced repression of Cd transporter genes (LOC107894197, LOC107955631, LOC107899273) in roots. Thus, melatonin induced downregulation of the Cd transporter genes further inhibited Cd ion transport towards leaf tissues. This suggests that the differentially expressed transporter genes (DEG) are key drivers of the melatonin-mediated regulation of Cd transportation and sequestration in cotton. Melatonin also protected cotton seedlings from Cd-induced oxidative injury by reducing tissues malondialdehyde (MDA) and hydrogen peroxide (H2O2) levels and increasing the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) enzymes. Transcriptomic analysis revealed that melatonin activated mitogen-activated protein kinase (MAPK) signaling pathways to simulate stomatal adjustment and photosynthesis in Cd-stressed leaves. Further, melatonin protects intercellular organs, particularly ribosomes, from Cd-induced oxidative damage by promoting ribosomal biosynthesis and improving translational efficiency. The findings elucidated the molecular basis of melatonin-mediated Cd stress tolerance in plants and provided a key for the effective strategy of Cd accumulation in cotton.
Assuntos
Gossypium , Melatonina , Antioxidantes/metabolismo , Cádmio/metabolismo , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Melatonina/farmacologia , Estresse Oxidativo , Plântula , Superóxido Dismutase/metabolismoRESUMO
Rhizosphere effect of nanoscale zero-valent iron (nZVI) is crucial but little reported. Maize seeds were dressed with four nZVI concentrations (0, 1.0, 1.5, 2 g kg-1 ) and inoculated with arbuscular mycorrhizal fungus (AMF) (Funneliformis mosseae). The SEM images illuminated that excessive nZVI particles (2 g kg-1 ) were agglomerated on the surface of hyphae and spore, causing severe deformation and inactivation of AMF symbionts and thereafter inhibiting water uptake in maize seedlings. This restrained the scavenging effects of enzymatic (superoxide dismutase, peroxidase) and non-enzymatic compounds (proline & malondialdehyde) on ROS, and leaf photoreduction activity and gas exchange ability (p < 0.05). Interestingly, the inoculation with AMF effectively alleviated above negative effects. In contrast, appropriate dose of nZVI, that is, ≤1.5 g kg-1 , can be evenly distributed on the hyphae surface and form the ordered symbionts with AMF. This help massively to enhance hyphae growth and water and nutrient uptake. The enhanced mycorrhizal infection turned to promote rhizosphere symbiont activity and leaf Rubisco and Rubisco activase activity. Light compensation point was massively lowered, which increased photosynthetic carbon supply for AMF symbionts. Particularly, such priming effects were evidently enhanced by drought stress. Our findings provided a novel insight into functional role of nZVI in agriculture and AMF-led green production.