Human activities generate wastes, some of which contain large amounts of heavy metals/metalloids that could enter natural ecosystems and alter the activities and functioning of soil micro- and ...macroorganisms. Microorganisms can adapt/resist to metal stress, and some of them are able to promote the plants establishment and therefore the phytoremediation process. In this context, the use of arbuscular mycorrhizal fungi (AMF), and their role in phytoremediation, has emerged as a new and interesting choice. In addition to AMF's well-known contribution to plant nutrient acquisition and growth, these fungi develop diverse mechanisms that encourage plants to grow in soils with high toxic metals concentrations. The authors are concerned about the AMF metal tolerance mechanisms and its role in the promotion of in phytoremediation processes.
The amount of glomalin-related soil protein (GRSP), a glycoprotein produced by arbuscular mycorrhizal fungi (AMF), its contribution to the sequestering of Cu and Zn in the soil, and the microsite ...variation of other soil traits (pH, water-stable aggregates—WSA, soil organic carbon—SOC) was studied in a semi-arid Mediterranean ecosystem near a copper smelter and affected by deposit of metal-rich particles since 1964. Rhizospheric (R) and non-rhizospheric (NR) soil of four representative plants (
Argemone subfusiformis,
Baccharis linearis,
Oenothera affinis and
Polypogon viridis) was analyzed. The results showed a strong variability in GRSP (6.6–36.8 mg g
−
1
), Cu content (62–831 mg kg
−
1
for the total Cu and 5.8–326 mg kg
−
1
for the available Cu) and pH (4.2–5.5) in the different plant and rhizospheric zones analyzed. A strong relationship between the GRSP with the soil Cu and Zn contents was found (
r
=
0.89 and 0.76 for Cu and Zn respectively,
p
<
0.001). The GRSP-bound Cu ranged from 3.76 to 89.0 mg g
−
1
soil and represents 1.44–27.5% of the total Cu content in soil. Moreover, the WSA reached 89% in
P. viridis R. For this plant, the C contained in GRSP represented up to 89% of SOC, and this coincided with the most extreme conditions of soil degradation within the ecosystem (the highest content of heavy metals and low pH values). This study provides evidence on the role of the GRSP in Cu and Zn sequestration and suggests a highly efficient mechanism of AMF to mitigate stress leading to stabilization of soils highly polluted by mining activities.
The monitoring of soil metal(loid) contamination is of global significance due to deleterious effects that metal(loid)s have on living organisms. Soil biological properties such as enzyme activities ...(EAs) are good indicators of metal(loid) contamination due to their high sensitivity, fast response, and low-cost. Here, the effect of metal(loid) contamination on physicochemical properties and microbial functionality in soils sampled from within 10 km of a Cu smelter is investigated. Soil composite samples were randomly taken within 2, 4, 6, 8 and10 km zones from a mining industry Cu smelter. The EAs of dehydrogenase (DHA), arylsulfatase (ARY), β-glucosidase, urease, and arginine ammonification (AA) were studied as indicators of metal(loid) contamination, which included the ecological dose (ED50) with respect to Cu and As contents. The community level physiological profile (CLPP), functional diversity, and catabolic evenness were evaluated based on the C-substrate utilisation. All EAs decreased in zones with high degrees of metal(loid) contamination, which also had low TOC and clay contents, reflecting long term processes of soil degradation. Positive and strong relationships between EAs and TOC were found. DHA and ARY activities decreased by approximately 85–90% in highly metal(loid) contaminated soils. DHA and AA showed significant ED50 values associated with available Cu (112.8 and 121.6 mg CuDTPA kg−1, respectively) and total As contents (30.8 and 31.8 mg As kg−1, respectively). The CLPP showed different metabolic profiles along the metal(loid) contamination gradients. Long-term stress conditions in soils close to industrial areas resulted in the decreasing of general biological activity, catabolic capacity, and functional diversity.
Display omitted
•Soil metal(loid) contamination assessment requires sensitive indicators.•Long-term metal(loid) contamination declined total organic carbon and clay contents.•Endoenzyme activities strongly decreased with higher metal(loid) contamination.•C-substrate utilisation decreased with higher metal(loid) contamination.•Soil metal(loid) contamination strongly affected general biological activity.
The phosphorus (P) addition can be helpful in the mitigation of the adverse effects of water deficit stress. However, the efficiency of wheat in utilizing both components has not been assessed in ...field conditions. This research aims to assess the effects of P and water addition on phosphorus use efficiency (PUE) and water productivity (WP) in field conditions for select wheat cultivars co-adapted to climate-induced agronomic challenges. Three wheat cultivars were selected based on their PUE and water WP from a previous experiment. The trials were conducted in field conditions over two consecutive years, from 2020 to 2021 (Season 1) and 2021–2022 (Season 2). The plants were grown on an andisol with a soil P concentration of 10 mg P kg−1 and 30 mg P kg−1. Two irrigation treatments were imposed: Well-watered (+W) and dryland (-W). The plants were sampled at three stages: tillering (Z25), anthesis (Z65), and ripening (Z95). At the end of the phenological cycle, grain yield components, grain yield, grain quality, PUE, and WP were evaluated. Phosphorus addition promotes plant growth, especially in the early vegetative stages, by enhancing tiller development and nutrient and water uptake. These effects were critical during the anthesis and ripening stages, enhancing yield components and higher grain production. Differential responses were observed across cultivars, underscoring the genotype-specificity in PUE and WP. Seasonal water deficit stress modulated these effects, highlighting a more complex genotype-environment-nutrient interaction. The water addition promoted PUE and WP, suggesting a synergy between the two components. Among the cultivars, Chevignon outperformed in grain yield, PUE, and WP. However, while phosphorus, water, and environmental factors influenced grain quality, the genetic background of the cultivar was the primary determinant of these components. This study advocates for implementing individual nutrient management strategies tailored to the specific cultivar and adaptable to environmental conditions under climate change.
Display omitted
•Phosphorus boosts wheat growth by 30% under dryland conditions.•Phosphorus enhances gluten and protein content in wheat under dryland conditions.•Phosphorus use efficiency (PUE) varies across phenological stages and wheat cultivars.•The genetic background of cultivars predominantly determines wheat grain protein and gluten composition.
Salinization of soils and freshwater resources by natural processes and/or human activities has become an increasing issue that affects environmental services and socioeconomic relations. In ...addition, salinization jeopardizes agroecosystems, inducing salt stress in most cultivated plants (nutrient deficiency, pH and oxidative stress, biomass reduction), and directly affects the quality and quantity of food production. Depending on the type of salt/stress (alkaline or pH-neutral), specific approaches and solutions should be applied to ameliorate the situation on-site. Various agro-hydrotechnical (soil and water conservation, reduced tillage, mulching, rainwater harvesting, irrigation and drainage, control of seawater intrusion), biological (agroforestry, multi-cropping, cultivation of salt-resistant species, bacterial inoculation, promotion of mycorrhiza, grafting with salt-resistant rootstocks), chemical (application of organic and mineral amendments, phytohormones), bio-ecological (breeding, desalination, application of nano-based products, seed biopriming), and/or institutional solutions (salinity monitoring, integrated national and regional strategies) are very effective against salinity/salt stress and numerous other constraints. Advances in computer science (artificial intelligence, machine learning) provide rapid predictions of salinization processes from the field to the global scale, under numerous scenarios, including climate change. Thus, these results represent a comprehensive outcome and tool for a multidisciplinary approach to protect and control salinization, minimizing damages caused by salt stress.
Purpose
Copper (Cu) contamination has been increasing in land ecosystems due to economic development activities. Excessive amount of Cu in soils is toxic to both plants and microorganisms. Biochar ...(BC) is known to immobilize soil Cu. The objectives of this research were to investigate the effects of chicken-manure-derived BC (CMB) on Cu immobilization, and growth of native metallophyte
Oenothera picensis
in a Cu-contaminated soil.
Materials and methods
A Cu-contaminated sandy soil (338 mg Cu kg
−1
) was spiked and equilibrated with additional Cu (0, 100, and 500 mg Cu kg
−1
). The spiked soil was then amended with CMB (0, 5, and 10 %
w/w
) and incubated for 2 weeks. The metallophyte was grown on these treatments under greenhouse conditions for 3 months. Pore water solutions were collected from the plant pots every 30 days. After the harvest, soil and pore water pH, soil Cu fractions, pore water Cu concentration, soil microbial activity, plant biomass weight, and Cu concentration in plant parts were determined.
Results and discussion
The CMB increased the pH of soils and soil pore water, and probably also soil major nutrients. It reduced the exchangeable fraction of Cu but increased its organic matter and residual fractions. At the same time, it decreased the Cu concentration in the soil pore water. The CMB increased basal respiration and dehydrogenase activity. The CMB application produced up to three and seven times more root and shoot biomass, respectively. In addition, shoots accumulated lesser Cu than control but roots did more. Plants survived in soil that was spiked with 500 mg Cu kg
−1
, only when CMB dose was 10 %.
Conclusions
The CMB affected the Cu uptake in plant by altering the mobility, bioavailability, and spatial distribution of Cu in soils. The increase in available nutrients and decrease in Cu toxicity facilitated plant growth. The increased microbial activity probably also promoted the plant growth and reduced the Cu bioavailability. Therefore, CMB can be used to remediate Cu-contaminated soils.
This study was carried out to evaluate the effects of foliar sprays containing boron (B) nano-fertilizer (NF) on the growth and physiology of lettuce (Lactuca sativa) and zucchini (Cucurbita pepo). ...Plants were grown under greenhouse conditions for 60 days on a modified Hoagland solution with the presence and absence of boron (+B or –B). A synthesized B–NF foliar spray and a commercial B foliar fertilizer (Bortrac™ 150, BT) was applied at a concentration of 30 mg B L−1 at 10-d intervals throughout the experiment. The B–NF treatment increased the growth of lettuce 2.7- and 1.9-fold for shoots and roots, respectively, with an average production of lettuce biomass by ~58%. Similarly, the NF increased the growth of zucchini by 18 and 66% compared with Control–B (the absence of B), and 13 and 36% compared with BT, both for shoots and roots, respectively. Nevertheless, NF + B mostly decreased lettuce growth with symptoms of B toxicity in leaves. In lettuce, addition of B did not affect concentrations of phenols; however, in zucchini, Control–B induced a higher production of phenolic compounds possibly related to B deficiency. The B addition in lettuce reduced the DPPH activity by 32 and 21% in NF and BT, respectively, compared to Control-B. These responses were similar in zucchini; however, the effect of B was product of its presence in mineral solution rather than due the foliar product applied. This suggests that a NF-based delivery system for B may be highly effective at boosting plant productivity on B-limited soils.
•A Boron (B)-based nanoparticle fertilizer (NF) was synthesized.•The synthesized B-based NF increased lettuce and zucchini root and shoot biomass.•The absence of B induced greater production of phenolic compounds.•The synthesized B-based NF was effective at overcoming B limitation.
Biochar (BC) is gaining attention as a soil amendment that can remediate metal polluted soils. The simultaneous effects of BC on copper (Cu) mobility, microbial activities in soil using metallophytes ...have scarcely been addressed. The objective of this study was to evaluate the effects of biochar BCs on Cu immobilization and over soil microbial communities in a Cu-contaminated soil evaluated over a two-year trial.
A Cu-contaminated soil (338mgkg−1) was incubated with chicken manure biochar (CMB) or oat hull biochar (OHB) at rates of 1 and 5% w/w. Metallophyte Oenothera picensis was grown over one season (six months). The above process was repeated for 3 more consecutive seasons using the same soils.
The BCs increased the soil pH and decreased the Cu exchangeable fraction Cu by 5 and 10 times (for OHB and CMB, respectively) by increasing the Cu bound in organic matter and residual fractions, and its effects were consistent across all seasons evaluated. BCs provided favorable habitat for microorganisms that was evident in increased microbial activity. The DHA activity was increased in all BC treatments, reaching a maximum of 7 and 6 times higher than control soils in CMB and OHB. Similar results were observed in microbial respiration, which increased 53% in OHB and 61% in CMB with respect to control. The BCs produced changes in microbial communities in all seasons evaluated. The fungal and bacterial richness were increased by CMB and OHB treatments; however, no clear effects were observed in the microbial diversity estimators.
The physiochemical and microbiological effects produced by BC result in an increase of plant biomass production, which was on average 3 times higher than control treatments. However, despite being a metallophyte, O. picensis did not uptake Cu efficiently. Root and shoot Cu concentrations decreased or changed insignificantly in most BC treatments.
Display omitted
•Biochar reduced bioavailable Cu fraction up to 10 times.•Biochar increased microbial activities in soil.•Biochar produced changes in fungal and bacterial communities.•Biochar play a positive role promoting better plant growth.
•Oat hull biochar has a significantly higher N, P, K content than Pine bark biochar.•Biochar significantly improved shoot and root biomass of T. aestivum.•Biochar promotes changes in soil fungal and ...bacterial communities.•The biochar stimulates positively the indigenous AM fungi propagules.•The treatments assayed enhance some soil quality properties in a volcanic soil.
Biochar (BC) production from agroforestry wastes and mycorrhizal fungi are potentially important agricultural practices for improving crops yields and increasing phosphorus (P) in volcanic soils. This study aimed to test the effect of BC application on wheat biomass and grain yield production, indigenous arbuscular mycorrhizal (AM) fungi propagules and soil microbial community and related to soil quality properties of an Andisol in Southern Chile. Biochars (BCs) were produced from oat hulls (OBC) and pine bark (PBC). Doses of 0, 5, 10, and 20 Mg ha−1 of BCs were applied on soil using wheat as the test crop. Wheat biomass (root and shoot portion) and grain yield, AM root colonization, spore, mycelium density, and glomalin content (glomalin related soil protein, EE-GRSP) were measured and related with soil quality properties such as bulk density, water-stable aggregates (WSA), and water holding capacity (WHC).
The OBC had a significantly higher macronutrients content (N, P, K) than PBC. The highest dose of both BCs significantly improved shoot and root biomass and wheat grain yield. Application of 20 Mg ha−1 of OBC and PBC increased AM spore density and root colonization relative to control treatment. In the same way, the BC application significantly affects the AM mycelium density. The results showed that the application of higher BC dose changed the soil microbial community. The use of BCs in this volcanic soil is an effective strategy to increase wheat biomass, increase grain yield production, stimulate the indigenous AM fungi activity, enhance soil quality properties, and increase the sustainability levels of agricultural systems.
Metallic oxides and clay minerals have gained increasing interest as additives of composting due to their influence in greenhouse gas emissions reduction and their effectivity in the stabilization of ...carbon both in compost and soils, leading to a cleaner compost production and potentially C sequestrant amendments. In this study, wheat straw (WS) was co-composted with iron oxide and allophanic soil and their influence on WS composting and composition of the end-products was evaluated. WS compost and their humic like-substances (HS) fraction were characterized by chemical and spectroscopic analyzes. After 126 days of process, the elemental composition showed slight differences of the N content for compost and HS, where the C/N atomic ratio tended to decrease relative to the initial material (WS; ~130). This trend was more pronounced in the HS from co-composted treatments (<30). The addition of inorganic materials increased the total acidity and phenolic-OH group contents (~15 and 14 mEq g−1 respectively, iron oxide treatment) relative to the treatment without inorganic additives. Nevertheless, the FTIR and solid-state 13CNMR spectroscopy barely support the wet chemical analysis and revealed a similar final composition between all the studied compost treatments. These results suggest that the incorporation of these materials as compost additives had no major effect on the spectroscopic features of the end-products, however, critical changes of the properties such as the extractability, functionality and composition of HS were revealed by traditional methods. In conclusion, the supply of metal oxides and clays could impact the aerobic composting of WS favorizing the stabilization of certain C pools and adsorptive properties of the end-products, that is of importance in production of amendments suitable for being used in degraded and contaminated soils. Nevertheless, under the experimental conditions of our research C stabilization apparently depends of other mechanisms that still need to be elucidate.
Display omitted
•The addition of inorganic materials decreased the C/N ratio in compost and HS.•Iron oxide and allophanic soil increase the extractability of N and lignin in HS.•Iron oxide decreased the final E4/E6 ratio associated to the stabilization of compost.•The inorganic materials enhance total acidity and phenolic group contents.•FTIR and solid-state 13CNMR showed similar composition of final composts.
