AimsPecan (Carya cathayensis Sarg.) is an important forest trees in China, the application of chemical pesticides for disease control has caused severe damage to the soil, including reduced fertility and disruption of microbial communities. Although Trichoderma treatment has been shown to promote plant growth and improve soil quality, its effects on the growth promotion of pecan and the impact on soil microbial communities and physicochemical properties remained unclear.MethodsIn this study, we investigated the impact of T. asperellum TCS007 spore suspension and its fermented crude extract on the growth and development of pecan seedlings. We also explored the effects of TCS007 treatment on the nutrients, enzyme activities, and microbial diversity in the rhizosphere soil of pecan seedlings during their three main growth stages.ResultsTreatment with TCS007 spore suspension or crude extract promoted the growth of pecan seedlings, with significantly higher levels of leaf hormones and defense enzyme activity compared to the control (CK). Moreover, the content of soil organic matter and ammonium nitrogen, as well as the activity of soil enzymes such as catalase and urease, were all significantly higher than CK after treatment, and the soil pH shifted from slightly acidic to slightly alkaline. The results indicated that TCS007 treatment significantly increased the richness of beneficial fungi and bacteria in the soil.ConclusionThe results demonstrated that TCS007 treatment significantly promoted the growth of pecan plants, increased enzyme activity and nutrient content in the soil, and improved the soil micro-ecological environment.

Woody plants have received considerable attention for the phytoremediation of heavy metal-contaminated soil. This study aimed to investigate the changes in antioxidant enzyme activity, macroelement uptake and microstructure of the woody plant Robinia pseudoacacia (black locust) for the phytoremediation of cadmium (Cd) and lead (Pb) co-contaminated soil based on dynamic sampling. The results show that black locust demonstrates strong tolerance in Cd and Pb co-contaminated soil. After 30-120 days of cultivation, the activities of superoxide dismutase, peroxidase and the macroelement (potassium [K] and calcium [Ca]) content in plant leaves significantly declined in response to Cd and Pb. However, after 160 d of cultivation, the antioxidant enzyme activities, chlorophyll, sulfhydryl and soluble protein contents, as well as Ca and magnesium content in plant leaves were returned to normal levels under the 40 mg kg(-1) Cd and 1000 mg kg(-1) Pb contaminated soil (CdPb3). Meanwhile, K content in plant leaves under the CdPb3 treatment was significantly (P < 0.05) increased by 68.9% compared with the control. Cadmium and Pb were primarily accumulated in black locust roots. Scanning electron microscope analysis indicated that the sieve tubes in the roots and stems of plant might block the transport of Cd and Pb. Transmission electron microscope analysis indicated that the number and volume of osmiophilic particles in plant leaves were increased and the cell walls were thickened in response to Cd and Pb stress. Path analysis further indicated that the growth of plant was related to macroelements uptake and physiological change (photosynthesis, antioxidant enzyme activity and chelation). Thus, black locust could effectively regulate the antioxidant defense system, macroelement absorption and microstructure to enhance plant tolerance to Cd and Pb stress. Moreover, black locust could maintain the normal urease, acid phosphatase and sucrase activities in the Cd and Pb co-contaminated soil. These findings suggest that black locust could be considered as a useful woody plant for the phytostabilization in Cd- and Pb-contaminated soil.

Fire has important effects on soil properties and functioning in terrestrial ecosystems that have been explored by many studies. Limited information exists on the alterations in soil parameters over time caused by fire disturbance in semi-arid climates. This study is designed to examine the influence of fire disturbance on the change of soil physical, chemical, and biological properties over time in a semi-arid region. In the summer of 2007, a severe natural fire occurred in the Pideh region of northern Iran, dominated by hawthorn (Crataegus melanocarpa M.B.) and berberis (Berberis integerrima Bunge), which destroyed almost 80 % of the shrubs and the majority of the co-dominant plants over a vast area. For this research, 12 soil samples (0-10 cm depth) were taken in summer (August) in different years (i.e., 2010, 2013, 2016, 2019, and 2022) from the burnt area. Furthermore, a total of 12 soil samples were collected during the summer (August) of 2022 from unburned regions to serve as a control. Soil biological parameters were studied by conducting soil samplings in the summer (August) and autumn (November) of every year. To evaluate soil N mineralization, soil samplings were done in summer (August and September) and autumn (November and December). Our results indicated that the occurrence of fire increased soil bulk density, with a concomitant decline in soil organic matter (SOM), porosity, aggregate stability, particulate organic carbon and nitrogen (POC and PON), as well as available nutrients such as ammonium (NH4+) and nitrate (NO3-) levels. Additionally, microbial parameters (respiration and biomass) and enzymes (urease, acid phosphatase, arylsulfatase and invertase), experienced a decrease in areas affected by the fire over time of 2010 to 2022. Unburnt (2022) and burnt (2022) sites had higher density and biomass of the three earthworm groups. Acari, Collembola, nematodes, protozoans, fungi and bacteria were significantly affected by fire disturbance in the different seasons, and years, and declined in the order unburnt sites > burnt sites 2022 > burnt sites 2019 > burnt sites 2016 > burnt sites 2013 > burnt sites 2010, respectively. Fire has complex effects on soil, involving interactions among physical, chemical, and biological properties that may persist for a prolonged period. After fifteen years of fire disturbance, soil characteristics were different in the burned (2022) and unburned areas. This research offers valuable insights into the impact of fire on soil characteristics over time, as well as a comparison with an unburned area. Therefore, it is essential to adopt soil management practices to minimize soil disruption in burned areas and facilitate the full recovery of soil ecosystems after fire damage.

The effectiveness of almond shell-derived biochar (ASB) in immobilizing soil heavy metals (HMs) and its impact on soil microbial activity and diversity have not been sufficiently studied. Hence, a pot study was carried out to investigate the effectiveness of ASB addition at 2, 4, and 6 % (w/w) w /w) on soil biochemical characteristics and the bioavailability of Cd, Cu, Pb, and Zn to tomato ( Solanum lycopersicum L.) plants, as compared to the control (contaminated soil without ASB addition). The addition of ASB promoted plant growth (up to two-fold) and restored the damage to the ultrastructure of chloroplast organelles. In addition, ASB mitigated the adverse effects of HMs toxicity by decreasing oxidative damage, regulating the antioxidant system, improving soil physicochemical properties, and enhancing enzymatic activities. At the phylum level, ASB addition enhanced the relative abundance of Actinobacteriota, , Acidobacteriota, , and Firmicutes while decreasing the relative abundance of Proteobacteria and Bacteroidota. . Furthermore, ASB application increased the relative abundance of several fungal taxa ( Ascomycota and Mortierellomycota) ) while reducing the relative abundance of Basidiomycota in the soil. The ASB-induced improvement in soil properties, microbial community, and diversity led to a significant decrease in the DTPA-extractable HMs down to 41.0 %, 51.0 %, 52.0 %, and 35.0 % for Cd, Cu, Pb, and Zn, respectively, as compared to the control. The highest doses of ASB (ASB6) significantly reduced the metals content by 26.0 % for Cd, 78.0 % for Cu, 38.0 % for Pb, and 20.0 % for Zn in the roots, and 72.0 % for Cd, 67.0 % for Cu, 46.0 % for Pb, and 35.0 % for Zn in the shoots, as compared to the control. The structural equation model predicts that soil pH and organic matter are driving factors in reducing the availability and uptake of HMs. ASB could be used as a sustainable trial for remediation of HMs polluted soils and reducing metal content in edible plants.

Uncertainties about the ecophysiological response of plants to elevated temperature limit our ability to predict the impact of climate change on plants, especially in tropical and subtropical forests. One important source of the uncertainties is that the vast majority of warming studies manipulated only aboveground or only belowground temperature when in the real word warming takes place both aboveground and belowground. We used a full factorial design of air warming and soil warming with four temperature treatments: (1) unwarmed, (2) soil warming, (3) air warming, (4) soil plus air warming to explore the effects of warming on ecophysical processes/ characteristics of leaves and fine roots of Chinese-fir saplings. We measured photosynthesis, concentrations of oxidant substances, activity of antioxidant enzymes, and osmoregulatory substances in leaves and fine roots. We found that the soil warming increased photosynthetic rate by 68.9%, but air warming and soil plus air warming treatments did not. The concentrations of oxidant compounds, superoxide anion (O2- ), hydrogen peroxide (H2O2) and malondialdehyde (MDA) were higher in leaves than in fine roots under all treatments, possibly due to their differences in the degree of oxidative damage. Soil warming increased leaf catalase (CAT) activity by 58.5%, soil warming and air warming increased leaf peroxidase (POD) activity by 31% and 42.3%, respectively, and soil plus air warming increased leaf ascorbic acid peroxidase (APX) activity by 31%. These increases in antioxidant enzyme concentrations indicated that warming activated leaf antioxidant systems. The CAT activity was lower in leaves than in fine roots, while the POD activity and concentrations of osmoregulatory substances were higher in leaves than in fine roots across all treatments. Our study clearly illustrated that different warming treatments (aboveground and belowground) had different effects on plant growth and physiological processes. The differences in oxidant compounds and activities of antioxidant enzymes between leaves and fine roots indicated that warming affect different organs differently. This study provides insights into how climate warming may affect important physiological and biochemical processes in subtropical forests.

Organic material plays an essential role in the ecological restoration of different types of surfaces with engineering damage in extremely fragile environments. An outdoor mesocosm experiment was conducted to explore the effects of modified organic material on chemical, physical properties and microbial communities of reconstructed soil in ecologically restored engineering slopes of the Qinghai-Tibetan plateau. The physical and chemical properties of the soil indicate that the addition of modified organic materials significantly improves soil nutrients. In this area, organic carbon increased by 1.87 g.kg(-1) in the frame beam slopes compared with the control area, and the potassium content doubled. In addition, modified organic material effectively induced soil metabolism responses, mainly promoting the activities of soil enzymes like amylase, cellulase, urease, sucrase, and alkaline phosphatase. Moreover, addition of modified organic material noticeably changed the abundance and structure of microbial communities in soils. The enhanced concentrations of the signal molecules N-acylated-L-homoserine lactone and auto inductor peptide indicated that addition of modified organic materials significantly influenced quorumsensing in soil microbial communities. There are differences in the soil improvement effects of different types of slopes, among which the frame grid beam has the best effect. These findings demonstrate the effect and underlying mechanisms of the addition of incorporating modified organic materials, primarily sodium carboxymethyl cellulose and anionic polyacrylamide, into the soil of engineering slopes. These results have extensive application prospects for ecological restoration in strict environments.

The use of engineered nanomaterials (NMs) as novel antimicrobial agents has garnered significant attention in agriculture. The antimicrobial properties of 5 mg/kg metal oxide (copper oxide and zinc oxide nanoparticles, CuO and ZnO NPs)- and carbon (reduced graphene oxide and multiwalled carbon nanotubes, rGO and MWCNT)-based NMs on two soil-borne fungal pathogens, Fusarium oxysporum f.sp. lactucae (F.o.lact) and Fusarium oxysporum f.sp. lycopersici (F.o.lyco), were evaluated over a 21-day incubation period. Both metal- and carbon-based NMs reduced the dehydrogenase activity (DHA) in Fusarium-infested soil by more than 40% relative to the infested controls; the efficacy of antifungal efficacy was CuO NPs > ZnO NPs > rGO > MWCNT. Similar decreases in the soil activities of urease (UE), sucrase (SC), acid phosphatase (ACP), and polyphenol oxidase (PPO) suggest that NMs could effectively inhibit Fusarium growth in soil over time. The total available metal fractions, including acid extractable fraction, Fe/Mn oxidation state, and the fraction bound to organic matter, were increased by 5.99-7.29% with metal-based NM compared to the infested controls. The Shannon index of microbial communities in the infested soils with metal-based NMs was increased by 12.2-23.5% relative to infested controls. Similarly, carbon-based NMs increased the Shannon index of the fungal community by 10.18-29.86%. Importantly, the relative abundance of Fusarium was decreased with both metal- and carbon-based NMs. These NMs also increased the relative abundance of beneficial microorganisms in infested soil, such as Pseudomonas, which was increased by 29.7-96.2% with metal-based NMs relative to the untreated controls. These findings demonstrate that NMs at appropriate doses could inhibit the Fusarium abundance and subsequent crop damage while simultaneously fostering the development of beneficial microorganisms in soil.

BACKGROUND AND OBJECTIVES: Streams that pass through densely populated areas and business and industrial centers are continuously threatened by various pollutants, including metals and microplastics, originating from dispersed sources. Biomonitoring is necessary to evaluate the health of stream ecosystems, considering that streams are essential ecologically and for human life. A biomonitoring approach through multimarkers can provide a comprehensive picture of the condition of stream ecosystems. It can identify biomarkers that are sensitive and specific to the presence of certain types of pollutants. This study evaluates the ecosystem health of Code Stream, Yogyakarta, Indonesia, through active biomonitoring by transplanting mussels Anodonta woodiana into cages at three stations, representing mild (station 1), moderate (station 3), and severe (station 2) polluted ecosystem conditions based on human activities around the stream. METHODS: The mussels were transplanted into the Code Stream. Then, on days 0, 3, 7, 14, 21, and 28, the organisms were taken, and their gills and mantle were dissected in the laboratory. The organs were analyzed for microplastic accumulation and characteristics, copper concentration, superoxide dismutase, catalase, acetylcholinesterase activities, metallothionein concentration, and deoxyribonucleic acid damage. Biomarkers sensitive to pollutants were evaluated by integrated biomarker response. The combined effects of the complexity of environmental factors on the biomarkers were analyzed by multiple-factor analysis. FINDINGS: The Code Stream waters at all stations were polluted with microplastics and copper. The increase in the two pollutants in the mussel organs was a function of time, with no differences among stations. The abundance of microplastics and copper concentrations in the water was closely related to their accumulation in both organs. Exposure to various contaminants in the stream strongly increased the superoxide dismutase and catalase activities in both organs at the beginning of exposure in all stations, with the highest being at station 3. The acetylcholinesterase activity was strongly inhibited in the gills at station 2. The metallothionein concentration slightly increased, and the highest increase occurred in the gills at station 2. The deoxyribonucleic acid damage was more intense at stations 2 and 3. Integrated biomarker response analysis showed that deoxyribonucleic acid damage, catalase activity, and metallothionein concentration were biomarkers responsive to stream pollution. Multiple -factor analysis revealed that superoxide dismutase, catalase, and acetylcholinesterase activities were biomarkers that indicated the environmental pollution of Code Stream waters. Multimarker analysis confirmed that the pollution level at stations 2 and 3 was higher than at station 1. CONCLUSION: Active biomonitoring can offer a more accurate and comprehensive view of the time -dependent link between exposure and biomarker response. This active biomonitoring strategy identified sensitive and specific biomarkers for the presence of metal and pesticide contaminants in stream ecosystems. The pollution of Code Stream waters harms oxidatively stressed mussels and may endanger human health via the food chain. This work contributes substantially to understanding pollution exposure and its effect on mussels. It develops pollution -sensitive biomarkers for routine stream health monitoring. Mitigation activities involving diverse stakeholders and public education on sustainable management efforts must continue to achieve sustainable development.

Spring, especially the freeze-thaw season, is considered the key period for the growth and carbon sequestration of desert mosses. It is not clear how the change in environment water and temperature affects the physiological characteristics of desert mosses in freeze-thaw season. In this study, the effects of water and freeze-thaw cycles on the physiological characteristics of Syntrichia caninervis were assessed by manipulating the increase or removal of 65% snow and changes in the freeze-thaw cycles. The results showed that the changes in snow depth, freeze-thaw cycles, and their interaction significantly affected the plant water content, osmoregulatory substances content, antioxidant substance, and antioxidant enzyme activities. The contents of free proline, soluble sugar, ascorbic acid (AsA), reduced glutathione (GSH), and malondialdehyde (MDA), and superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities increased significantly with the decrease in snow depth and freeze-thaw cycles. POD and free proline were the most sensitive to the snow depth and freeze-thaw cycles, while SOD and CAT were the least sensitive. Therefore, compared with the increase in freeze-thaw cycles, the reduction in freeze-thaw cycles weakened the physiological sensitivity of S. caninervis to snow depth changes.

The northern regions are experiencing considerable changes in winter climate leading to more frequent warm periods, rain-on-snow events and reduced snow pack diminishing the insulation properties of snow cover and increasing soil frost and freeze-thaw cycles. In this study, we investigated how the lack of snow cover, formation of ice encasement and snow compaction affect the size, structure and activities of soil bacterial and fungal communities. Contrary to our hypotheses, snow manipulation treatments over one winter had limited influence on microbial community structure, bacterial or fungal copy numbers or enzyme activities. However, microbial community structure and activities shifted seasonally among soils sampled before snow melt, in early and late growing season and seemed driven by substrate availability. Bacterial and fungal communities were dominated by stress-resistant taxa such as the orders Acidobacteriales, Chaetothyriales and Helotiales that are likely adapted to adverse winter conditions. This study indicated that microbial communities in acidic northern boreal forest soil may be insensitive to direct effects of changing snow cover. However, in long term, the detrimental effects of increased ice and frost to plant roots may alter plant derived carbon and nutrient pools to the soil likely leading to stronger microbial responses.