Effect of Soil pH on the Growth, Reproductive Investment and Pollen Allergenicity of Ambrosia artemisiifolia L

Impact of cement waste on soil fertility and crop productivity: a serious concern for food security

The rapid expansion of urbanization and construction activities has led to a significant increase in cement production worldwide, resulting in a surge in cement waste generation. This study aims to provide a comprehensive analysis of the repercussions of cement waste on soil fertility and crop productivity, emphasizing its critical implications for global food security. Through a multidisciplinary approach, encompassing field surveys, laboratory experiments, and statistical modeling, we assess the physicochemical alterations induced by cement waste in agricultural soils. Our findings reveal substantial declines in crucial soil parameters, including pH levels, organic matter content, and nutrient availability, which directly translate into diminished crop yields. Furthermore, the study identifies key mechanisms underlying these detrimental effects, including altered microbial communities and disrupted nutrient cycling processes. In addition, the findings underscore the severity of the issue, revealing substantial declines in soil fertility and crop yields in areas affected by cement waste contamination. Additionally, we discuss potential mitigation strategies and policy interventions aimed at mitigating the adverse effects of cement waste on agricultural systems. By quantifying the extent of soil degradation and crop yield reduction attributed to cement waste, this research underscores the urgency for sustainable waste management practices and highlights the need for policy interventions to safeguard agricultural productivity and ensure global food security in the face of escalating urbanization and construction activities.

Pollen and sub-pollen particles: External interactions shaping the allergic potential of pollen

Pollen allergies, such as allergic rhinitis, are triggered by exposure to airborne pollen. They are a considerable global health burden, with their numbers expected to rise in the coming decades due to the advent of climate change and air pollution. The relationships that exist between pollens, meteorological, and environmental conditions are complex due to a lack of clarity on the nature and conditions associated with these interactions; therefore, it is challenging to describe their direct impacts on allergenic potential clearly. This article attempts to review evidence pertaining to the possible influence of meteorological factors and air pollutants on the allergic potential of pollen by studying the interactions that pollen undergoes, from its inception to atmospheric traversal to human exposure. This study classifies the evidence based on the nature of these interactions as physical, chemical, source, and biological, thereby simplifying the complexities in describing these interactions. Physical conditions facilitating pollen rupturing for tree, grass, and weed pollen, along with their mechanisms, are studied. The effects of pollen exposure to air pollutants and their impact on pollen allergenic potential are presented along with the possible outcomes following these interactions, such as pollen fragmentation (SPP generation), deposition of particulate matter on pollen exine, and modification of protein levels in-situ of pollen. This study also delves into evidence on plant-based (source and biological) interactions, which could indirectly influence the allergic potential of pollen. The current state of knowledge, open questions, and a brief overview of future research directions are outlined and discussed. We suggest that future studies should utilise a multi-disciplinary approach to better understand this complex system of pollen interactions that occur in nature.

Environmental impacts on intraspecific variation in Ambrosia artemisiifolia genome size in Slovakia, Central Europe

The quantity of DNA in angiosperms exhibits variation attributed to many external influences, such as environmental factors, geographical features, or stress factors, which exert constant selection pressure on organisms. Since invasive species possess adaptive capabilities to acclimate to novel environmental conditions, ragweed (Ambrosia artemisiifolia L.) was chosen as a subject for investigating their influence on genome size variation. Slovakia has diverse climatic conditions, suitable for testing the hypothesis that air temperature and precipitation, the main limiting factors of ragweed occurrence, would also have an impact on its genome size. Our results using flow cytometry confirmed this hypothesis and also found a significant association with geographical features such as latitude, altitude, and longitude. We can conclude that plants growing in colder environments farther from oceanic influences exhibit smaller DNA amounts, while optimal growth conditions result in a greater variability in genome size, reflecting the diminished effect of selection pressure.

Understanding the dynamic interactions of root-knot nematodes and their host: role of plant growth promoting bacteria and abiotic factors

Root-knot nematodes (Meloidogyne spp., RKN) are among the most destructive endoparasitic nematodes worldwide, often leading to a reduction of crop growth and yield. Insights into the dynamics of host-RKN interactions, especially in varied biotic and abiotic environments, could be pivotal in devising novel RKN mitigation measures. Plant growth-promoting bacteria (PGPB) involves different plant growth-enhancing activities such as biofertilization, pathogen suppression, and induction of systemic resistance. We summarized the up-to-date knowledge on the role of PGPB and abiotic factors such as soil pH, texture, structure, moisture, etc. in modulating RKN-host interactions. RKN are directly or indirectly affected by different PGPB, abiotic factors interplay in the interactions, and host responses to RKN infection. We highlighted the tripartite (host-RKN-PGPB) phenomenon with respect to (i) PGPB direct and indirect effect on RKN-host interactions; (ii) host influence in the selection and enrichment of PGPB in the rhizosphere; (iii) how soil microbes enhance RKN parasitism; (iv) influence of host in RKN-PGPB interactions, and (v) the role of abiotic factors in modulating the tripartite interactions. Furthermore, we discussed how different agricultural practices alter the interactions. Finally, we emphasized the importance of incorporating the knowledge of tripartite interactions in the integrated RKN management strategies.

Effects of soil pH on the growth, soil nutrient composition, and rhizosphere microbiome of Ageratina adenophora

Ageratina adenophora is an invasive weed species found in many countries. Methods to control the spread of this weed have been largely unsuccessful. Soil pH is the most important soil factor affecting the availability of nutrients for plant and impacting its growth. Understanding the mechanisms of the influence of soil pH on the growth of A. adenophora may help to develop effective control measures. In this study, we artificially changed the soil pH in pot experiments for A. adenophora. We studied the effects of acidic (pH 5.5), weakly acidic (pH 6.5), neutral (pH 7.2), and alkaline (pH 9.0) soils on the growth, availability of soil nutrients, activity of antioxidant enzymes, levels of redox markers in the leaves, and the structure and diversity of the rhizosphere microbiome. Soil with a pH 7.2 had a higher (47.8%) below-ground height versus soils of pH 5.5 at day 10; plant had a higher (11.3%) above-ground height in pH 7.2 soils than pH 9.0 soils at day 90; no differences in the fresh and dry weights of its above- and belowground parts, plant heights, and root lengths were observed in plants growing in acid, alkaline, or neutral pH soil were observed at day 180. Correspondingly, the antioxidant enzymes SOD (superoxide dismutase), POD (peroxidase), CAT (catalase) and redox markers GSH (glutathione) and MDA (malondialdehyde) were measured in the leaves. Significant differences existed in the activities of CAT and the levels of GSH between those growing in acidic and alkaline soils and those in neutral pH soil at day 90; however, only lower (36.8%) CAT activities in those grown at pH 5.5 than those grown at pH 7.2 were found at day 180. Similarly, significant differences in available P (16.89 vs 3.04 mg Kg-1) and total K (3.67 vs 0.96 mg Kg-1), total P (0.37 vs 0.25 g Kg-1) and total N (0.45 vs 1.09 g Kg-1) concentrations were found between the rhizosphere soils of A. adenophora grown at pH 9.0 and 7.2 at day 90; no such differences were seen at day 180. High throughput analyses of the 16S rRNA and ITS fragments showed that the rhizosphere microbiome diversity and composition under different soil pH conditions changed over 180 days. The rhizosphere microbiomes differed in diversity, phylum, and generic composition and population interactions under acid and alkaline conditions versus those grown in neutral soils. Soil pH had a greater impact on the diversity and composition of the prokaryotic rhizosphere communities than those of the fungal communities. A. adenophora responded successfully to pH stress by changing the diversity and composition of the rhizosphere microbiome to maintain a balanced nutrient supply to support its normal growth. The unusual pH tolerance of A. adenophora may be one crucial reason for its successful invasion. Our results suggest that attempts use soil pH to control its invasion by changing the soil pH (for example, using lime) will fail.

Bacillus-derived consortium enhances Ginkgo biloba's health and resistance to Alternaria tenuissima

BACKGROUND

Bacillus, as a plant-growth-promoting rhizobacteria, can enhance the resistance of plants to phytopathogens. In our study, Bacillus strains showing excellent biocontrol were screened and used to control ginkgo leaf blight (Alternaria tenuissima).

RESULTS

Four biocontrol Bacillus strains-Bsa537, Bam337, Bso544, and Bsu503-were selected from 286 isolates based on their capacity to inhibit pathogens and promote plant growth. The four Bacillus strains significantly improved the resistance of ginkgo to leaf blight. This was especially the case when the four strains were used as a mixture, which contributed to a decrease in lesion area of >40%. Hence, a mixture of Bacillus strains was used to control ginkgo leaf blight in the field. Treatment efficiency varied from 30% to 100% (average 81.5%) and was higher than that of the control (-2% to -18%, average - 8.5%); the antioxidant capacity of the treated ginkgo was also stronger. In addition, ginkgo biomass increased as a result of treatment with the Bacillus mixture, including leaf weight, area, thickness, number of lateral roots and root weight. Furthermore, the Bacillus mixture improved the ginkgo rhizosphere soil by boosting the number of beneficial microorganisms, lowering the number of pathogens and hastening soil catabolism.

CONCLUSION

The Bacillus mixture improved the health status of ginkgo by protecting it from pathogen attack, promoting its growth and improving the microorganism community in the rhizosphere. This work closes a technological gap in the biological control of ginkgo leaf blight, investigates application methods for compound Bacillus biofertilizers and establishes a framework for the popularity and commercialization of these products. © 2024 Society of Chemical Industry.

Influence of soil amendments on phytostabilization, localization and distribution of zinc and cadmium by marigold varieties

Marigolds (Tagetes erecta L.) were evaluated for phytoremediation potential of cadmium (Cd) and zinc (Zn) as a function of amendment application to soil. Vermicompost (V), biodigestate (Bi), and combined V + Bi (VBi) were used as soil amendments in Zn and Cd co-contaminated soils. Application of soil amendments can alter physicochemical properties of soils, particularly pH, EC, CEC and nutrient concentrations. The VBi treatment resulted in highest percentage growth rate in biomass (52 %) for the Twenty yellow variety of marigold. Also, in the VBi treatment, leaves of Dragon yellow variety exhibited maximal accumulation of Zn and Cd. Flower extracts of Twenty yellow in the V treatment had substantial carotenoid content (71.7 mg L-1) and lowest IC50 value (43.7 mg L-1), thus indicating it had highest DPPH free radical scavenging activity. Dragon yellow exhibited highest values of ferric reducing antioxidant power (FRAP; 2066 mg L-1), total flavonoids content (TFC; 64.1 mg L-1), and total phenolics content (TPC; 50.9 mg L-1). Using X-ray fluorescence (XRF) spectroscopy, the atomic percentages of Zn and Cd in all marigold varieties and treatments showed similar patterns over flower surfaces, seeds, and flower petals in descending order. Prime yellow in the V treatment resulted in higher Zn accumulation in roots (bioconcentration factor of root value) > 1 and translocation factor value < 1, indicating an enhanced ability of the plant for phytostabilization. Application of V altered antioxidant activities and production of bioactive compounds as well as enhanced the excluder potential of Cd and Zn, particularly in the Prime yellow variety. Application of Bi contributed to increased flower numbers, suggesting that floriculturists cultivating marigolds for ornamental purposes may be able to generate revenue in terms of productivity and quality of flowers when marigolds are grown on contaminated land.

The plant growth promoting rhizobacterium Achromobacter sp. 5B1, rescues Arabidopsis seedlings from alkaline stress by enhancing root organogenesis and hormonal responses

Soil alkalinity is a critical environmental factor for plant growth and distribution in ecosystems. An alkaline condition (pH > 7) is imposed by the rising concentration of hydroxides and cations, and prevails in semiarid and arid environments, which represent more than 25% of the total arable land of the world. Despite the great pressure exerted by alkalinity for root viability and plant survival, scarce information is available to understand how root microbes contribute to alkaline pH adaptation. Here, we assessed the effects of alkalinity on shoot and root biomass production, chlorophyll content, root growth and branching, lateral root primordia formation, and the expression of CYCB1, TOR kinase, and auxin and cytokinin-inducible trangenes in shoots and roots of Arabidopsis seedlings grown in Petri plates with agar-nutrient medium at pH values of 7.0, 7.5, 8.0, 8.5, and 9.0. The results showed an inverse correlation between the rise of pH and most growth, hormonal and genetic traits analyzed. Noteworthy, root inoculation with Achromobacter sp. 5B1, a beneficial rhizospheric bacterium, with plant growth promoting and salt tolerance features, increased biomass production, restored root growth and branching and enhanced auxin responses in WT seedlings and auxin-related mutants aux1-7 and eir1, indicating that stress adaptation operates independently of canonical auxin transporter proteins. Sequencing of the Achromobacter sp. 5B1 genome unveiled 5244 protein-coding genes, including genes possibly involved in auxin biosynthesis, quorum-sensing regulation and stress adaptation, which may account for its plant growth promotion attributes. These data highlight the critical role of rhizobacteria to increase plant resilience under high soil pH conditions potentially through genes for adaptation to an extreme environment and bacteria-plant communication.

The factors affecting the development of medicinal plants from a value chain perspective

MAIN CONCLUSION

From a value chain perspective, this paper examines the important factors from the selection of planting areas to storage, which restrict the development of medicinal plants. The purpose of this paper is to provide theoretical basis for the sustainable development of medicinal plants. Medicinal plants have significant economic and medicinal value. Due to the gradual depletion of wild medicinal plant resources, cultivators of medicinal plants must resort to artificial cultivation to cope. However, there are still many problems in the production process of medicinal plants, resulting in decreases in both yield and quality, thus hindering sustainable development. To date, research on the value chain of medicinal plants is still limited. Therefore, this paper analyzes the factors affecting the development of medicinal plants from the perspective of the value chain, including the selection of growing areas to the storage process of medicinal plants, and summarizes the challenges faced in the production process of medicinal plants. The purpose of this paper is to provide theoretical basis for the sustainable development of medicinal plants.

Monitoring plant responses in field-grown peanuts exposed to exogenously applied chitosan under full and limited irrigation levels

In recent decades, numerous studies have examined the effects of climate change on the responses of plants. These studies have primarily examined the effects of solitary stress on plants, neglecting the simultaneous effects of mixed stress, which are anticipated to transpire frequently as a result of the extreme climatic fluctuations. Therefore, this study investigated the impact of applied chitosan on boosting the resistance responses of peanuts to alkali and mixed drought-alkali stresses. Peanuts were grown in mid-alkaline soil and irrigated with full irrigation water requirements (100%IR), represented alkali condition (100% IR × alkali soil) and stress conditions (70% IR × alkali soil-represented mixed drought-alkali conditions). Additionally, the plants were either untreated or treated with foliar chitosan. The study evaluated various plant physio-chemical characteristics, including element contents (leaves and roots), seed yield, and irrigation water use efficiency (IWUE). Plants that experienced solitary alkali stress were found to be more vulnerable. However, chitosan applications were effective for reducing (soil pH and sodium absorption), alongside promoting examined physio-chemical measurements, yield traits, and IWUE. Importantly, when chitosan was applied under alkali conditions, the accumulations of (phosphorus, calcium, iron, manganese, zinc, and copper) in leaves and roots were maximized. Under mixed drought-alkali stresses, the results revealed a reduction in yield, reaching about 5.1 and 5.8% lower than under (100% IR × alkali), in the first and second seasons, respectively. Interestingly, treated plants under mixed drought-alkali stresses with chitosan recorded highest values of relative water content, proline, yield, IWUE, and nutrient uptake of (nitrogen, potassium, and magnesium) as well as the lowest sodium content in leaves and roots. Enhances the accumulation of (N, K, and Mg) instead of (phosphorus, calcium, iron, manganese, zinc, and copper) was the primary plant response to chitosan applications, which averted severe damage caused by mixed drought-alkali conditions, over time. These findings provide a framework of the nutrient homeostasis changes induced by chitosan under mixed stresses. Based on the findings, it is recommended under mixed drought-alkali conditions to treat plants with chitosan. This approach offers a promising perspective for achieving optimal yield with reduced water usage.

Early-stage growth and elemental composition patterns of Brassica napus L. in response to Cd-Zn contamination

Soil contamination caused by the presence of Cd and the excess amount of Zn is a widespread concern in agricultural areas, posing significant risks to the growth and development of crops. In this paper, the early-stage development and metal (Cd and Zn) accumulation potential of rapeseed (Brassica napus L.) grown under different metal application schemes were assessed by determining radicle and hypocotyl length and the micro- and macro elemental composition of plantlets after 24, 72, and 120 h. The results indicated that the single and co-application of Cd and Zn significantly reduced the radicle and hypocotyl lengths. Accumulation intensity for Cd and Zn was affected by Cd and the combination of Cd and Zn in the solution, respectively. In addition, both metals significantly influenced the tissue Mn and had a minor effect on Cu and Fe concentrations. Both Cd and Zn significantly affected macro element concentrations by decreasing tissue Ca and influencing K and Mg concentrations in a dose- and exposure time-dependent manner. These findings specify the short-term and support the long-term use of rapeseed in remediation processes. However, interactions of metals are crucial in determining the concentration patterns in tissues, which deserves more attention in future investigations.

Responses of non-structural carbohydrates and biomass in plant to heavy metal treatment

The contamination of heavy metals profoundly impacts plant metabolic processes and various physiological indicators, such as non-structural carbohydrates (NSC). However, a comprehensive understanding of how NSC in plants respond to heavy metal treatment and how different experimental setting and plant types affect the response of plant NSC is still lacking. Here, we compiled data of 2084 observations of NSC from 85 published studies and conducted a meta-analysis to investigate the responses of soluble sugars, starch, the ratio of soluble sugar to starch, and total non-structural carbohydrates (TNSC) to heavy metal treatment. Our results showed that, under heavy metal treatment, foliar soluble sugars, foliar TNSC, and the ratio of soluble sugars to starch in both foliage and root increased significantly by 21.6 %, 11.6 %, 55.9 %, and 65.1 %, respectively; and foliar starch, root starch, and root TNSC decreased significantly by 10 %, 23.3 %, and 11 %, respectively; while root soluble sugars remained unchanged. The treatment of heavy metals significantly diminished the biomass of foliage, above-ground, and root by 12.3 %, 29.5 %, and 34.3 %, respectively. The responses of foliar NSC to heavy metal treatment were strongly dependent on leaf habit, the duration and concentration of heavy metal treatment, and soil pH value. The magnitude of the response of NSC to heavy metals increased with the duration and concentration of heavy metal treatment. Furthermore, the types of heavy metals modulated the magnitude of the response of foliar NSC to heavy metal treatment. Overall, our findings provide valuable insights into the responses of plant NSC to heavy metal stress and contribute to a comprehensive understanding of this crucial aspect of plant physiology.

Nutrient treatment of greywater in green wall systems: A critical review of removal mechanisms, performance efficiencies and system design parameters

Greywater has lower pathogen and nutrient levels than other mixed wastewaters, making it easier to treat and to reuse in nature-based wastewater treatment systems. Green walls (GWs) are one type of nature-based solutions (NBS) that are evolving in design to support on-site and low-cost greywater treatment. Greywater treatment in GWs involves interacting and complex physical, chemical, and biological processes. Design and operational considerations of such green technologies must facilitate these pivotal processes to achieve effective greywater treatment. This critical review comprehensively analyses the scientific literature on nutrient removal from greywater in GWs. It discusses nutrient removal efficiency in different GW types. Total nitrogen removal ranges from 7 to 91% in indirect green facades (IGF), 48-93% for modular living walls (MLW), and 8-26% for continuous living walls (CLW). Total phosphorus removal ranges from 7 to 67% for IGF and 2-53% for MLW. The review also discusses the specific nutrient removal mechanisms orchestrated by vegetation, substrates, and biofilms to understand their role in nitrogen and phosphorus removal within GWs. The effects of key GW design parameters on nutrient removal, including substrate characteristics, vegetation species, biodegradation, temperature, and operating parameters such as irrigation cycle and hydraulic loading rate, are assessed. Results show that greater substrate depth enhances nutrient removal efficiency in GWs by facilitating efficient filtration, straining, adsorption, and various biological processes at varying depths. Particle size and pore size are critical substrate characteristics in GWs. They can significantly impact the effectiveness of physicochemical and biological removal processes by providing sufficient pollutant contact time, active surface area, and by influencing saturation and redox conditions. Hydraulic loading rate (HLR) also impacts the contact time and redox conditions. An HLR between 50 and 60 mm/d during the vegetation growing season provides optimal nutrient removal. Furthermore, nutrient removal was higher when watering cycles were customized to specific vegetation types and their drought tolerances.

A review on the fate and effects of contaminants in biosolids applied on land: Hazards and government regulatory policies

The increase in world population growth and its resultant increase in industrial production to meet its need, have continued to raise the volume of wastewater received by treatment plant facilities. This has expectedly, led to an upsurge in the volume of sewage sludge and biosolids generated from wastewater treatment systems. Biosolids are best managed by application on land because of their agronomic benefits. However, this usage has been discovered to negatively affect humans and impact the environment due to the accumulation of minute concentrations of contaminants still present in the biosolid after treatment, hence the need for government regulations. This review article examined the fate and effects of pollutants, especially persistent organic pollutants (PoPs) of concern and emerging contaminants found in biosolids used for land applications, and also discussed government regulations on biosolid reuse from the perspectives of the two major regulations governing biosolid land application-the EU's Sludge Directive and USEPA's Part 503 Rule, in an attempt to draw attention to their outdated contents since enactment, as they do not currently meet the challenges of biosolid land application and thus, require a comprehensive update. Any update efforts should focus on USEPA's Part 503 Rule, which is less stringent on the allowable concentration of biosolid pollutants. Furthermore, an update should include specific regulations on new and emerging contaminants and persistent organic pollutants (PoPs) such as microplastics, pharmaceutical and personal care products (P&PCPs), surfactants, endocrine-disrupting chemicals, flame retardants, pathogens, and organic pollutants; further reduction of heavy metal standard limits, and consideration of soil phosphate-metal interactions to regulate biosolid agronomic loading rate. Future biosolid research should focus on the concentration of TCS, TCC, and emerging pharmaceuticals, as well as Microplastic transport in biosolid-amended soils, soil-plant transfer mechanism, and metabolism of PFAs in the soils; all of which will inform government policies on biosolid application on land.

Response of Diverse Peanut Cultivars to Nano and Conventional Calcium Forms under Alkaline Sandy Soil

Calcium is one of the most limiting factors for the growth and reproduction of peanut, which ultimately affects pod and seed yields. A two-year field experiment was carried out to assess the impact of five calcium applications, including nano-calcium and conventional forms, on growth, leaf nutrient content, yield traits, and quality parameters of three diverse peanut cultivars (Ismailia-1, Giza-5, and Giza-6). The applied calcium applications were calcium sulfate, which is recommended for commercial peanut cultivation and commonly referred to as gypsum (coded as Ca-1), calcium nitrate (Ca-2), nano-calcium nitrate (Ca-3), 50% calcium nitrate + 50% nano-calcium (Ca-4), and 50% calcium sulfate + 50% nano-calcium (Ca-5). Calcium sulfate (gypsum, Ca-1) was soil-supplied during the seedbed preparation as recommended, while the other calcium applications (Ca-2, Ca-3, Ca-4, and Ca-5) were exogenously sprayed three times at 30, 45, and 60 days after sowing. The soil of the experimental site was alkaline, with a high pH of 8.6. The results revealed significant differences among cultivars, calcium applications, and their interactions. The soil-supplied gypsum Ca-1 displayed lower agronomic performance on all recorded growth, leaf nutrient content, yield traits, and quality parameters. On the other hand, the foliar-supplied calcium, particularly Ca-4 and Ca-5, displayed superior effects compared to the other simple calcium forms. Ca-4 and Ca-5 produced significantly higher seed yield (3.58 and 3.38 t/ha) than the simple recommended form (Ca-1, 2.34 t/ha). This could be due to the difficulty of calcium uptake from soil-supplied calcium under high soil pH compared to the exogenously sprayed nano-calcium form. Moreover, the superior performance of Ca-4 and Ca-5 could be caused by the mixture of fertilizers from the synergistic effect of calcium and nitrate or sulfate. Furthermore, the effect of nitrate was applied in nano form in the Ca4 and Ca-5 treatments, which contributed to improving nutrient uptake efficiency and plant growth compared to the other treatments. The peanut cultivar Giza-6 showed superiority for most measured traits over the other two cultivars. The interaction effect between the assessed cultivars and calcium applications was significant for various traits. The cultivar Giza-6 showed a significant advantage for most measured traits with the mixture of 50% calcium nitrate + 50% nano-calcium (Ca-4). Conclusively, the results pointed out the advantage of the exogenously sprayed nano-calcium form combined with calcium nitrate or calcium sulfate for promoting growth, leaf nutrient content, yield, and quality traits of peanut, particularly with high-yielding cultivars under sandy soil with high pH.

Geological Substrate Effects on Teucrium montanum L. (Lamiaceae) Morphological Traits: Geometric Morphometrics Approach

The shape-environment relationship in plants refers to the ways in which the physical characteristics and structures of plants are influenced by their environment. Plants have evolved a remarkable ability to adapt to their specific habitats, and their shape and form play a crucial role in determining their survival and reproductive success. This study aimed to examine differences in size and shape between morphological traits in mountain germander (Teucrium montanum L.) from different geological substrates (calcareous and serpentinite). For this study, 400 individuals of T. montanum from 20 populations (ten populations from the serpentinite and ten from the calcareous substrate) were selected. Using the geometric morphometrics approach, it was shown that the degree of phenotypic variation in the size and shape of the corolla, leaf, and stem of T. montanum depends on the type of substrate. The main differences between the populations are the narrower part of the lower lip of the corolla, the narrower leaf, and the wider central part of the vascular system stem from serpentinite populations. The results of this study will contribute to a better understanding of the morphological variability of T. montanum in relation to edaphic conditions. In addition, the results confirm that certain morphological differences play an important role in the adaptive response in relation to substrate composition, especially for substrates with increased metal content, such as serpentinite. The shape-environment relationship in plants could define diversity and complexity in plant life, and underscores the importance of shape as a key factor in their survival and success in different habitats.

Metabolically versatile psychrotolerant Antarctic bacterium Pseudomonas sp. ANT_H12B is an efficient producer of siderophores and accompanying metabolites (SAM) useful for agricultural purposes

BACKGROUND

Bacterial siderophores are chelating compounds with the potential of application in agriculture, due to their plant growth-promoting (PGP) properties, however, high production and purification costs are limiting factors for their wider application. Cost-efficiency of the production could be increased by omitting purification processes, especially since siderophores accompanying metabolites (SAM) often also possess PGP traits. In this study, the metabolism versatility of Pseudomonas sp. ANT_H12B was used for the optimization of siderophores production and the potential of these metabolites and SAM was characterized in the context of PGP properties.

RESULTS

The metabolic diversity of ANT_H12B was examined through genomic analysis and phenotype microarrays. The strain was found to be able to use numerous C, N, P, and S sources, which allowed for the design of novel media suitable for efficient production of siderophores in the form of pyoverdine (223.50-512.60 μM). Moreover, depending on the culture medium, the pH of the siderophores and SAM solutions varied from acidic (pH < 5) to alkaline (pH > 8). In a germination test, siderophores and SAM were shown to have a positive effect on plants, with a significant increase in germination percentage observed in beetroot, pea, and tobacco. The PGP potential of SAM was further elucidated through GC/MS analysis, which revealed other compounds with PGP potential, such as indolic acetic acids, organic acids, fatty acids, sugars and alcohols. These compounds not only improved seed germination but could also potentially be beneficial for plant fitness and soil quality.

CONCLUSIONS

Pseudomonas sp. ANT_H12B was presented as an efficient producer of siderophores and SAM which exhibit PGP potential. It was also shown that omitting downstream processes could not only limit the costs of siderophores production but also improve their agricultural potential.

UV-C photon integrated surface dielectric barrier discharge hybrid reactor: A novel and energy-efficient route for rapid mineralisation of aqueous azo dyes

The study describes developing an energy-efficient and scalable alternative to conventional non-thermal plasma systems by integrating surface dielectric barrier discharge (SDBD) and UV-C radiation sources. The unprecedented enhancement in the mineralisation rate of an azo dye (brilliant red 5B) by the hybrid reactor (photo-SDBD) is demonstrated thoroughly as a function of dye concentrations, pH, and background salts. The photo-SDBD is 1.25 - 4.9 times more energy efficient than SDBD under similar experimental conditions. The photo-SDBD could overcome the problems such as the recombination of hydroxyl radicals and scavenging of radicals by salts (NaCl, Na₂SO₄, Na₂CO₃) observed in conventional non-thermal plasma systems. The TOC and HR-MS analysis establish the complete mineralisation potential and chemical mineralisation pathway. Besides, the phytotoxicity of the treated water is tested and demonstrated its utility as a liquid fertiliser for enhanced germination of mung bean seeds. The optical emission spectroscopy measurements were performed to estimate the plasma's electron temperature (1.6 ± 0.2 eV) and density (10²¹/m³). The emission line ratio (I_763.5/I_738.3) approach is used to compare the influence of UV-C on plasma parameters in the SDBD reactor. The study opens a new pathway for developing energy-efficient and scalable plasma-assisted mineralisation of complex and emerging organic pollutants.

Degraded land rehabilitation through agroforestry in India: Achievements, current understanding, and future prospectives

Land degradation is one of the most important factors responsible for the alarming situation of food security, human health, and socioeconomic development in the country. Currently, 120.7 M ha of land in the country is affected by land degradation, out of which 85.7 M ha of land is affected by soil erosion caused by water and wind. Moreover, physical, chemical, and biological degradation are the major forms of land degradation in the country. Deforestation or tree cover loss (2.07 M ha) from 2001 to 2021, intensive rainfall (&gt;7.5 mm ha−1), uncontrolled grazing (5.65 M ha), indiscriminate use of fertilizers (32 MT year−1), and shifting cultivation (7.6 M ha) are other major factors that further aggravate the process of land degradation. In order to alleviate the problem of land degradation, numerous agroforestry technologies have been developed after years of research in different agroclimatic zones of the country. The major agroforestry systems observed in the country are agri-horticulture, silvipasture, and agri-silviculture. This review indicates the potential of agroforestry in enhancing carbon sequestration (1.80 Mg C ha−1 year−1 in the Western Himalayan region to 3.50 Mg C ha−1 year−1 in the island regions) and reduced soil loss and runoff by 94% and 78%, respectively, in Northeast India. This can be concluded that the adoption of the agroforestry system is imperative for the rehabilitation of degraded lands and also found to have enough potential to address the issues of food, environmental, and livelihood security. This review’s findings will benefit researchers, land managers, and decision-makers in understanding the role of agroforestry in combating land degradation to enhance ecosystem service in India and planning suitable policies for eradicating the problem effectively.

Earthworm Aporrectodea molleri (oligochaeta)'s coelomic fluid-associated bacteria modify soil biochemical properties and improve maize (Zea mays L.) plant growth under abiotic stress conditions

This study evaluated the impact of Aporrectodea molleri's coelomic fluid-associated bacteria (CFB) on Zea mays L. growth and soil biochemical characteristics under abiotic stress conditions, including alkaline soil (pH = 8) and nitrogen (N), phosphate (P), and potassium (K) deficit. Compared to maize cultivated in uninoculated soil, the effect of CFB on boosting plant growth under abiotic stress was notably exceptional. Different CFB treatments increased significantly root and shoot length by 50% and 21%, respectively. Furthermore, the presence of isolates in soil resulted in a significant increase in plant fresh and dry weights (of up to 113% and 91% for roots, and up to 173% and 44% for shoots), leaf surface (78%), and steam diameter (107%). Overall, soil inoculation with CFB significantly (P < 0.05) enhanced chlorophyll and water content in the plant compared to the untreated soil. Despite the soil's alkaline condition, CFB drastically boosted soil quality by increasing nutrient availability (up to 30 ppm for N, 2 ppm for P, and 60 ppm for K) and enzyme activity (up to 1.14 μg p-NP h^-1 g^-1 for acide phosphatase, 9 μg p-NP h^-1 g^-1 for alkaline phosphatase and 40 μg NH₄-N 2 h^-1 g^-1 for urease), throughout the early stages of the growth period. Interestingly, alkaline phosphatase concentrations were substantially greater in treatments with different isolates than acid phosphatase. Furthermore, the principal component analysis showed that the inoculation with bacteria strains CFB1 Buttiauxella gaviniae and CFB3 Aeromonas hydrophila had a significantly better stimulatory stimulatory and direct influence on maize growth than the other isolates had a substantial effect on soil's biochemical features. Thus, we assumed that the beneficial contribution of earthworms in the rhizosphere might be attributed in large part to associated microorganisms.

Germination Response of Datura stramonium L. to Different pH and Salinity Levels under Different Temperature Conditions

Weeds can be one of the most severe threats to crop production, especially when they are widespread and highly adaptable. Part of the adaptive strategy of plants is the ability to germinate in different conditions. Germination is the first developmental phase of plant life and is fundamental for its establishment. In this work, the germination of two populations of Datura stramonium L. at two different sites in Croatia (one cropped, the other non-agricultural) was tested under a wide range of salinity stress, 4, 8, 12, and 16 dS/m, and pH stress, values 1-9, at two temperature ranges of 15-25 °C and 18-30 °C. The results show that this species can tolerate high salinity, with a high number of seeds germinating, even under the highest level of saline stress and especially at higher temperatures: 21.7% of seeds germinated at 15-25 °C and 51.2% at 18-30 °C. D. stramonium also appears to be quite acid tolerant, with a significant reduction in germination only at pH 2, and no germination only at pH 1. Germination was always higher at higher temperatures, independently of abiotic stress. Although there were some differences between the two populations in the final germination percentages, they were similar in their responses to the abiotic stresses.

Elevated CO2 and Increased N Intensify Competition between Two Invasive Annual Plants in China

As multiple invaders often co-occur, understanding the interactions between different invasive species is important. Previous studies have reported on invasional meltdown and neutral and interference relationships between invasive species. However, interspecific interactions may vary with environmental change owing to the different responses of interacting invaders. To better understand the interaction of notorious invasive alien plants under CO₂ enrichment and N deposition, the growth characteristics of common ragweed (Ambrosia artemisiifolia) and redroot pigweed (Amaranthus retroflexus) were studied when they were planted in monoculture (4Rag and 4Pig) or mixture (1Rag:3Pig, 2Rag:2Pig, 3Rag:1Pig) under four environmental treatments: elevated CO₂, increased N, elevated CO₂ + increased N and a control. Increased N positively affected almost all the traits (basal stem diameter, height, shoot biomass, root biomass and total biomass) of common ragweed, except for branch number and root-shoot ratio. But increased N only promoted redroot pigweed's height and basal stem diameter. interspecific competition promoted basal stem diameter and number of branches but decreased root biomass of common ragweed, and the basal stem diameter was significantly higher in 1Rag:3Pig and 2Rag:2Pig compared to the other two treatments. interspecific competition inhibited almost all the characteristics of redroot pigweed. The interaction between elevated CO₂ and increased N also increased the biomass characteristics (shoot biomass, root biomass and total biomass) of common ragweed. However, elevated CO₂ inhibited the root biomass of redroot pigweed. The results indicated that common ragweed was a superior competitor under conditions of elevated CO₂ and increased N. Moreover, environmental change might strengthen the super-invasive plant common ragweed's competitive ability.

Allelopathic potential and allelochemical composition in different soil layers of Rhododendron delavayi forest, southwest China

Forests habituated by Rhododendron delavayi often lack understory vegetation, which could possibly be a consequence of allelopathy. It is a phenomenon by virtue of which certain plant species produce allelochemicals that affect the growth and behavior of surrounding plants. To elucidate the allelopathic potential and allelochemicals present in the different layers of a R. delavayi forest, extracts obtained from three layers of the forest were used for seed germination bioassays and gas chromatography-mass spectrometry (GC–MS) analysis. Aqueous extracts of the litter and humus layers significantly inhibited the seed germination of R. delavayi, Festuca arundinacea, and Lolium perenne, with the litter layer causing the strongest inhibitory effect. A total of 26 allelochemicals were identified in the litter, humus, and soil layers by GC–MS analysis. The primary allelochemicals in the soil and humus layer were organic acids, while the main allelochemicals in the litter layer were phenolic acids. The redundancy analysis revealed the significance of total nitrogen (TN) and relative water content (RWC) in explaining the distribution of the allelochemicals. The results indicated that the litter layer exerted the maximum allelopathic effect due to presence of maximum amount of allelochemical especially the phenolic acids.

Iron and zinc micronutrients and soil inoculation of Trichoderma harzianum enhance wheat grain quality and yield

Malnutrition is mainly caused by iron and zinc micronutrient deficiencies affecting about half of the world's population across the globe. Biofortification of staple crops is the right approach to overcome malnutrition and enhance nutrient contents in the daily food of humans. This study aimed to evaluate the role of foliar application of iron and zinc in Trichoderma harzianum treated soil on various growth characteristics, quality, and yield of wheat varieties. Plants were examined in the absence/presence of T. harzianum, and iron and zinc micronutrients in both optimal and high-stress conditions. Although the symbiotic association of T. harzianum and common wheat is utilized as an effective approach for wheat improvement because of the dynamic growth promoting the ability of the fungus, this association was found tremendously effective in the presence of foliar feeding of micronutrients for the enhancement of various growth parameters and quality of wheat. The utilization of this approach positively increased various growth parameters including spike length, grain mass, biomass, harvest index, and photosynthetic pigments. The beneficial role of T. harzianum in combination with zinc and iron in stimulating plant growth and its positive impact on the intensities of high molecular weight glutenin subunits (HMW-GS) alleles make it an interesting approach for application in eco-friendly agricultural systems. Further, this study suggests a possible alternative way that does not merely enhances the wheat yield but also its quality through proper biofortification of iron and zinc to fulfill the daily needs of micronutrients in staple food.

The Impact of Soil pH on Heavy Metals Uptake and Photosynthesis Efficiency in Melissa officinalis, Taraxacum officinalis, Ocimum basilicum

Herbs used in medicine should be grown under controlled and standardized conditions. Agricultural practices often induce changes to soil pH, which may affect migration of heavy metals in the environment, their accumulation in plant tissues and the concentration of medicinal ingredients. The aim of this work was to assess the influence of various soil pH on the biological parameters and uptake of manganese, copper and zinc by basil, dandelion and lemon balm. The soil analysis covered pH, organic matter content, bioavailable and total forms of investigated metals in soil. In plants cultivated in soil at pH covering the range 4.7–8.5 the concentrations of Mn, Cu and Zn were analyzed. Their mobility and availability were assessed by bioaccumulation factors, translocation factors and transfer coefficients. The seed germination and subsequent herbs growth were strongly dependent on soil pH for all investigated plant species. Photosynthetic efficiency at different pHs was positively correlated with uptake of Cu and Mn while Zn behaved in a more random way.

Distribution, Characterization and the Commercialization of Elite Rhizobia Strains in Africa

Grain legumes play a significant role in smallholder farming systems in Africa because of their contribution to nutrition and income security and their role in fixing nitrogen. Biological Nitrogen Fixation (BNF) serves a critical role in improving soil fertility for legumes. Although much research has been conducted on rhizobia in nitrogen fixation and their contribution to soil fertility, much less is known about the distribution and diversity of the bacteria strains in different areas of the world and which of the strains achieve optimal benefits for the host plants under specific soil and environmental conditions. This paper reviews the distribution, characterization, and commercialization of elite rhizobia strains in Africa.

Influence of chromium and sodium on development, physiology, and anatomy of Conilon coffee seedlings

Some components found in the composition of the tannery sludge are nutrients for the plants; it can be considered an alternative source of fertilization as they have favorable agronomic characteristics. However, it is reported in some studies that the presence of chromium and sodium in this residue causes physiological and anatomical disturbances that inhibit the development of the plants. The objective of this study was to evaluate the influence of chromium and sodium on the physiology, anatomy, and development of Conilon coffee seedlings grown on substrates produced with tannery sludge and equivalent doses of chromium and sodium. The experiment was carried out in nursery using randomized block design, containing 5 treatments and 7 repetitions. The treatments consisted of the application of a 40% tannery sludge dose and equivalent doses of chromium and sodium mixed with a conventional substrate. Notably, the presence of sodium in the substrate caused greater damage to the plants, negatively influencing the physiology, anatomy, and, consequently, development of the plants, while the presence of chromium suggests that it does not influence much the evaluated characteristics. The treatment with tannery sludge, on the other hand, despite containing the same chromium and sodium contents, revealed a more pronounced negative influence on the physiology, anatomy, and development patterns of the seedlings. This shows that sodium and chromium alone are not the only factors responsible for the lowest growth indicators studied.

Effect of Harvesting in Different Ripening Stages on the Content of the Mineral Elements of Rosehip (Rosa spp.) Fruit Flesh

Studies on the mineral content of different rosehip species/cultivars during the ripening period are very limited. Therefore, the objective of this research was to evaluate the content and composition of the mineral elements of two species and two rosehip cultivars growing on an organic farm. The rosehip fruits were harvested at different ripening stages, five time per season. Mineral composition (K, Ca, Mg, P, Fe, Na, Ti, Cu, B, Mn, Al, Zn, Cr, Co, Ni, As, Mo, Cd and Pb) was analyzed by means inductively coupled plasma mass spectrometry (ICP–MS). The results showed that the ripening stage and species/cultivars had an effect on the contents of the mineral elements. Significantly, the highest content of mineral elements was determined at ripening stage I (Ca, Mg, Ti, Mn, Al and Cr) and IV (K, P, Fe, Cu and B). Species of the Rosa canina accumulated the highest content of mineral elements. Correlation analysis showed that the hue angle had a positive and very strong relationship with six mineral elements: K (r = 0.909), Ca (r = 0.962), Mg (r = 0.965), P (r = 0.945), Fe (r = 0.929) and Ti (r = 0.944).

The Effect of Pelletized Lime Kiln Dust Combined with Biomass Combustion Ash on Soil Properties and Plant Yield in a Three-Year Field Study

Extensive application of mineral fertilizers resulted in high soil acidity, which is one of the major problems for crop production and soil degradation. Industrial solid waste, such as lime kiln dust and wood ash, can be used as alternative liming materials to benefit sustainable agricultural development. In this work, pelletized lime kiln dust with and without wood ash was utilized as liming material and the results of the three-year field study were compared with conventional mineral-based liming materials. It was determined that pelletized lime kiln dust satisfies the requirements posed by the recent European Union regulations to qualify as liming materials. The application of 2000 kg/ha Ca equivalent pelletized lime kiln dust increased soil pHKCl by ~0.55 pH units. Moreover, pelletized lime kiln dust significantly increased spring wheat grain yields ranging from 33.6% to 40.4%, depending on the pellet size. The usage of these liming materials not only increased crop yield but also decreased heavy metal concentration in soil. Due to high alkalinity, carbonate content, easy handling, and the transportation of pelletized lime kiln dust with and without wood ash, the materials have the potential to be used in agriculture as liming materials to reduce soil acidification and increase crop productivity or be used as soil amendments.

The Negative Effects of High Rates of Biochar on Violas Can Be Counteracted with Fertilizer

Increasing costs and environmental issues regarding excessive use of peat moss is impacting the horticultural industry. Biochar is a valuable substrate additive that has the potential to reduce the use of peatmoss in greenhouse production. However, its varying effects on ornamentals requires that individual species and cultivars of crops must be evaluated to determine the threshold for benefits. Viola cornuta is a high value ornamental crop; however, information on how different rates of biochar rates affect productivity and physiology of Viola cultivars in container production is not known. To determine if biochar rates could increase the productivity of Viola, we mixed a peat-based substrate with 10, 25, and 50% (w:w) hardwood biochar in two studies on four cultivars. Without fertilizers, 10 and 25% biochar improved plant biomass, growth, root length, and flowering, but 50% biochar was found to have negative effects on plant growth and flowering. Cultivars varied in their response to biochar rates. When fertilizer was applied in the second experiment, biochar rates did not impact growth parameters or flowering. These results suggest that up to 25% biochar can be used in Viola production without detrimental impacts. However, 50% biochar can be used with the addition of fertilizer without negatively affecting plant growth. Biochar can have a short-term impact on the growth characteristics of Viola plants in container production, but fertilization and growing period of Viola may influence these effects. These results indicate that biochar could be the suitable replacement for peat moss, with up to 50% biochar rate in Viola production reducing the environmental and economic burden for peat moss.

Toxicity-removal efficiency of Brassica juncea, Chrysopogon zizanioides and Pistia stratiotes to decontaminate biomedical ash under non-chelating and chelating conditions: A pilot- scale phytoextraction study

The healthcare community acknowledged that bio-medical wastes (BMWs) have reached a colossal level across the globe. The recent pandemic (COVID-19) has brought a deluge of contaminated waste which calls for an urgent need of treatment technology for its safe disposal. BMW generally undergoes a conservative treatment approach of incineration which in turn generates potentially toxic ash known as BMW ash. BMW ash, if directly dumped in landfill, leaches and further pollutes both land and groundwater. The present study deployed Brassica juncea [Indian Mustard (IM)], Chrysopogon zizanioides [Vetiver Grass (VG)], and Pistia stratiotes [Water Lettuce (WL)] to remediate toxicity of potentially toxic elements (PTEs) i.e., Cd, Al, Pb, Cu, Mn, Co and Zn in BMW ash both in the presence and absence of chelate with an increased dosage of toxicity. The phyto-assessment results showed that IM extracted 202.2 ± 0.1-365.5 ± 0.02, 7.8 ± 0.03-12.5 ± 0.3, 132.1 ± 0.1-327.3 ± 0.1 and >100 mg kg^-1 of Al, Cd, Pb and Zn, respectively without the assistance of a chelating agent. The VG accumulated heavy metals in greater concentration up to 10.5 ± 0.1 and 290.1 ± 0.05 mg kg^-1 of Cd and Zn, respectively, and similar trends were observed in the WL set-up. However, the application of an ethylene diamine tetraacetic acid (EDTA) had also increased the efficiency on an average by 20-30% for IM, 35-45% for VG, and 25-35% for WL. The experimental set-up shows that the BCF for IM, VG and WL was found to be greater than 1 for most of the PTEs. The higher value of BCF resulted in a better ability to phytoextract the heavy metals from the soil. The results suggested that IM, VG and WL have the potential to phytoextract PTEs both in the absence and presence of chelating agents.

Co-occurrence of co-contaminants: Cyanotoxins and microplastics, in soil system and their health impacts on plant - A comprehensive review

Cyanotoxins (CTX) and micro/nanoplastics (M/NP) are ubiquitously distributed in every environmental compartment. But the distribution, abundance and associated ecological risks of CTX are still poorly understood in soil system. On the other hand, M/NP could serve as vectors for persistent organic/inorganic pollutants in the natural environment through the sorption of pollutants onto them. Thus, co-occurrence of CTX and M/NP in soils suggests the sorption of CTX onto M/NP. So, major aim of this review is to understand the relevance of CTX and M/NP in soils as co-contaminants, possible interactions between them and ecological risks of CTX in terms of phytotoxicity. In this study, we comprehensively discuss different sources and fate of CTX and the sorption of CTX onto M/NP in soil system, considering the partition coefficient of different phases of soil and mass balance. Phytotoxicity of CTX, CTX mixture and co-contaminants has also been discussed with insights on the mechanism of action. This study indicates the need for the evaluation of sorption between co-contaminants, especially CTX and M/NP, and their phytotoxicity assessment using environmentally relevant concentrations.

Management of phosphorus nutrient amid climate change for sustainable agriculture

Nutrients are essential for plant growth and development and influence overall agricultural production. Phosphorus (P) is a major nutrient required for many physiological and biochemical functions of a plant. Phosphate rock is the major source of phosphate fertilizer but is becoming increasingly limited in both developing and developed countries. The resources of phosphate rock need to be conserved, and import dependency on phosphate fertilizer needs to be minimized; this will help increase the availability of phosphate fertilizer over the next 300 yr. Climate change creates new challenges in the management of nutrients including P, affecting the overall production of crops. The availability, acquisition, and translocation of P are influenced by the fluctuation of temperatures, pH, drought, and elevated CO₂ . Both lower and higher soil temperatures reduce uptake and translocation of P. High soil pH affects P concentration and decreases the rate of plant P uptake. Low soil pH decreases the activity of soil microorganisms, the rate of transpiration, and P uptake and utilization. Elevated CO₂ decreases P uptake from soil by the plants. Future research is needed on chemical, molecular, microbiological, and physiological aspects to improve the understanding on how temperature, pH, drought, and elevated CO₂ affect the availability, acquisition, and transport of P by plants. Better P management strategies are required to secure the P supply to ensure long-term protection of soil fertility and to avoid environmental impacts such as eutrophication and water pollution, ensuring sustainable food production.

High Phenotypic Plasticity in a Prominent Plant Invader along Altitudinal and Temperature Gradients

Studies on plant growth and trait variation along environmental gradients can provide important information for identifying drivers of plant invasions and for deriving management strategies. We used seeds of the annual plant invader Ambrosia artemisiifolia L. (common ragweed) collected from an agricultural site in Northern Italy (226 m. a.s.l; Mean Annual Air Temperature: 12.9 °C; precipitations: 930 mm) to determine variation in growth trajectories and plant traits when grown along a 1000-m altitudinal gradient in Northern Italy, and under different temperature conditions in the growth chamber (from 14/18 °C to 26/30 °C, night/day), using a non-liner modeling approach. Under field conditions, traits related to plant height (maximum height, stem height, number of internodes) followed a three-parameter logistic curve. In contrast, leaf traits (lateral spread, number of leaves, leaf length and width) followed non-monotonic double-Richards curves that captured the decline patterns evident in the data. Plants grew faster, reaching a higher maximum plant height, and produced more biomass when grown at intermediate elevations. Under laboratory conditions, plants exhibited the same general growth trajectory of field conditions. However, leaf width did not show the recession after the maximum value shown by plants grown in the field, although the growth trajectories of some individuals, particularly those grown at 18 °C, showed a decline at late times. In addition, the plants grown at lower temperatures exhibited the highest value of biomass and preserved reproductive performances (e.g., amount of male inflorescence, pollen weight). From our findings, common ragweed exhibits a high phenotypic plasticity of vegetative and reproductive traits in response to different altitudes and temperature conditions. Under climate warming, this plasticity may facilitate the shift of the species towards higher elevation, but also the in situ resistance and (pre)adaptation of populations currently abundant at low elevations in the invasive European range. Such results may be also relevant for projecting the species management such as the impact by possible biocontrol agents.

The role of soils on pollination and seed dispersal

Ongoing environmental changes are affecting physical, chemical and biological soil components. Evidence of impacts of soil changes on pollinators' and seed dispersers' behaviour, fitness and density is scarce, but growing. Here, we reviewed information on such impacts and on a number of mechanisms that may explain its propagation, taking into account the full range of resources required by the large and diverse number of species of these two important functional groups. We show that while there is substantial evidence on the effects of soil nitrogen enrichment and changes in soil water content on the quality and quantity of floral and fruit resources, little is known on the effects of changes of other soil properties (e.g. soil pH, soil structure, other nutrients). Also, the few studies showing correlations between soil changes and pollinator and seed disperser foraging behaviour or fitness do not clearly identify the mechanisms that explain such correlation. Finally, most studies (including those with nitrogen and water) are local and limited to a small number of species, and it remains unclear how variable such effects are across time and geographical regions, and the strength of interactive effects between soil properties. Increasing research on this topic, taking into consideration how impacts propagate through species interaction networks, will provide essential information to predict impacts of ongoing environmental changes and help guide conservation plans that aim to minimize impacts on ecosystem functioning. This article is part of the theme issue 'The role of soils in delivering Nature's Contributions to People'.

Effects of soil amendments on leaf anatomical characteristics of marigolds cultivated in cadmium-spiked soils

The marigolds (Tagetes spp.) in this study were classified as excluders for cadmium (Cd); however, their leaves also accumulated substantial Cd content. Among the experimental treatments (i.e., control, cattle manure, pig manure, and leonardite which served as soil amendments), pig manure resulted in significantly increased growth performance for all marigold cultivars as seen by relative growth rates (119-132.3%) and showed positive effects on leaf anatomy modifications, e.g., thickness of spongy and palisade mesophyll, size of vein area and diameter of xylem cells. This may be due to substantially higher essential nutrient content, e.g., total nitrogen (N) and extractable phosphorus (P), in pig manure that aided all marigold cultivars, particularly the French cultivar which exhibited the highest relative growth rate (132.3%). In the Cd-only treatment, cell disorganization was observed in vascular bundles as well as in palisade and spongy mesophyll, which may have been responsible for the lowest plant growth performance recorded in this study, particularly among the American and Honey cultivars (RGR = 73% and 77.3%, respectively).

Nutrient availability and pH level affect germination traits and seedling development of Conyza canadensis

Reducing pesticide application in agricultural land is a major challenge for the twenty-first century. Responses of weed seed's germination and seedling's early development to chemical soil conditions around the seed may be a promising way to aid weed control in a no-till system. Thus, the objective of this work was to test, under controlled conditions, whether different chemical conditions affect the germination and development of horseweed [Conyza canadensis (L.) Cronquist]. We used, as treatment, solutions containing different nutrients (P, K, Ca, and Mg), separately and in combination, and at two pH levels (4.8 and 6.5). Phosphorus alone inhibited horseweed seed germination at ~ 7 times while had ~ 4 times reduction in final germination percentage and germination speed index for both pH tested. Other nutrients tested had a no-effect in germination speed index compared to the control treatment. Potassium alone or associated with other ions (P, Ca, and Mg) at pH 4.8 had a synergistic effect on seedling development (root and shoot length). In the same way, K associated with Mg was synergistic to the root length at pH 6.5. Seeds in the control treatment (distilled water) presented a high germination speed index at pH 6.5, while at low pH this parameter was higher when in association with KMg, PMg and Ca. The findings demonstrate that seed germination traits and seedling development of horseweed depend on nutrient kind exposure and pH conditions in the seed environment. This work suggests that adequate topsoil management (i.e., pH and nutrient availability) may aid to reduce weed germination, because, it consists of an important factor of weed occurrence in agricultural areas.

Application of Biochar Functionalized with Layered Double Hydroxides: Improved Plant Growth Performance after Use as Phosphate Adsorbent

The objective of this study was to verify the feasibility of using biochar, functionalized with layered double hydroxides, as a fertilizer after its use in phosphate treatment (P-BC-LDHs). It was conducted with several levels of P-BC-LDHs using seed germination and early growth assays of lettuce (Lactuca sativa L.). The application of P-BC-LDHs resulted in successful seedling emergence, with an excellent germination capacity of over 96% for all treatments. However, compared to the controls, P-BC-LDHs did not provide favorable seedling traits. In contrast, in the latter experiments, lettuce cultivated under mixtures with P-BC-LDHs, particularly at an application rate of 2.5% (w/w), displayed superior growth quality to those under non-treated conditions. The length of lettuce shoots and roots from this optimal dosage were increased by at least 24% compared to untreated samples. A 17% reduction in biomass yield was observed for the samples from non-supplemented substrates. The nutrient release profiles showed that P-BC-LDHs were capable of slowly supplying phosphorus, thereby increasing the long-term nutrient availability for plants. The findings reported here provide important insights into these materials and confirm that P-BC-LDHs can be used for agricultural purposes after phosphate remediation applications. The results of this study provide constructive information to facilitate the implementation of biochar-based LDH composites for sustainable phosphate removal and recovery.

Dependence of the Concentration of Bioactive Compounds in Origanum vulgare on Chemical Properties of the Soil

The aim of this study was to determine the dependence of the total phenolic, flavonoid, and extractive content in extracts of Origanum vulgare L. on the soil pH, humus, total nitrogen (N_total), and plant-available/mobile phosphorus (P₂O₅), as well as potassium (K₂O), total calcium (Ca), magnesium (Mg), and sodium (Na) concentrations. Experimental fields were formed in four locations in Lithuania. Soil and perennial O. vulgare samples were taken at three sites of each experimental field. A total of 12 samples of soil and 12 samples of the tested plant were collected and analyzed. The concentrations of bioactive compounds in plants are significantly (p < 0.05–0.01) affected by some chemical properties of the soil: the total phenolic content was reliably correlated with the soil pH, N_total, Ca, Mg, and P₂O₅; the flavonoid content was correlated with the soil P₂O₅, K₂O, Mg, and Na; and the extractive content was correlated with the soil humus, N_total, and Na. The obtained results are useful for the development of the commercial cultivation of O. vulgare.

The influence of feedstocks and additives in 23 added-value composts as a growing media component on Pythium irregulare suppressivity

Alternative materials with added-value functions, such as phytopathogen suppression and biostimulant and/or biofertilising activity, have been proposed as peat substitutes in growing media. The aim of this work was to evaluate the effect of 23 agro-industrial composts as components of growing media for baby-leaf lettuce transplant production and their activity against the plant pathogen Pythium irregulare. The composts were produced by mixing different starting feedstocks-tomato waste, leek waste, olive mill cake and vineyard pruning waste-with different additives (coffee, thyme, lavender and rockrose waste), which were incorporated at the beginning of the maturation phase. The results obtained indicated that the composts were mature enough to be used as growing media. The fresh weight of the lettuce plants grown with the different composts was significantly higher than in plants obtained with peat. Composts with the coffee additive produced higher lettuce fresh weight, while those with thyme yielded a lower fresh weight. Moreover, composts as components of growing media showed significantly higher P. irregulare suppressiveness than peat. The composts with additives produced lower lettuce fresh weight than composts without additives, but showed higher suppressiveness. Composts with additives showed opposite results depending on whether they were exposed to pathogens or not. Composts with additives showed opposite results according to pathogen pressure or not. Out of all the composts studied, the compost with tomato waste and leek waste as the initial feedstock, and lavender as an additive, showed the highest suppressive capacity. After lettuce harvesting, the growing media with composts showed significantly lower concentrations of P. irregulare than peat. Principal Component Analysis (PCA) revealed that the growing media with compost can be grouped together according to the additive type.

Enhancement of Photosynthetic Iron-Use Efficiency Is an Important Trait of Hordeum vulgare for Adaptation of Photosystems to Iron Deficiency

Leaf iron (Fe) contents in Fe-deficiency-tolerant plants are not necessarily higher than that in Fe-deficiency-susceptible ones, suggesting an unknown mechanism involved in saving and allowing the efficient use of minimal Fe. To quantitatively evaluate the difference in Fe economy for photosynthesis, we compared the ratio of CO₂ assimilation rate to Fe content in newly developed leaves as a novel index of photosynthetic iron-use efficiency (PIUE) among 23 different barley (Hordeum vulgare L.) varieties. Notably, varieties originating from areas with alkaline soil increased PIUE in response to Fe-deficiency, suggesting that PIUE enhancement is a crucial and genetically inherent trait for acclimation to Fe-deficient environments. Multivariate analyses revealed that the ability to increase PIUE was correlated with photochemical quenching (qP), which is a coefficient of light energy used in photosynthesis. Nevertheless, the maximal quantum yield of photosystem II (PSII) photochemistry, non-photochemical quenching, and quantum yield of carbon assimilation showed a relatively low correlation with PIUE. This result suggests that the ability of Fe-deficiency-tolerant varieties of barley to increase PIUE is related to optimizing the electron flow downstream of PSII, including cytochrome b₆f and photosystem I.

Sustainability in Perovskite Solar Cells

At a current value of 25.5%, perovskites have reached some of the highest power conversion efficiencies of all single-junction solar cell devices. Researchers, however, are questioning their readiness for the commercial market, citing reasons of the toxicity of the lead-based active layer and instability. Closer examination of the life cycle of perovskite solar cells reveals that there are more areas than just these which should be addressed in order to bring an environmentally friendly and sustainable technology to global use. In this review, we discuss these issues. Life cycle analyses show that high temperature processes, heavy use of organic solvents, and extensive use of certain materials can have high up and downstream consequences in terms of emissions, human and ecotoxicity. We further bring attention to the toxicity of the perovskites themselves, where the most direct analyses suggest that the lead cannot be considered totally safe, despite its small quantity and that replacements such as tin may be more toxic in certain scenarios. As a way to reduce the negative environmental impact, we highlight ways in which researchers have used encapsulation and recycling to extend the life of the entire unit and its components and to prevent lead leakage. We hope this review directs researchers toward new strategies to introduce a clean solar technology to the world.

Evaluating the Aqueous Phase From Hydrothermal Carbonization of Cow Manure Digestate as Possible Fertilizer Solution for Plant Growth

Improving the agronomic use of recycled nutrients derived from organic waste is one of the priorities within the measures adopted by the European community to reduce environmental issues but remains an unexplored area of research. This study focused on investigating the possibility of using innovative fertilizer solutions in hydroponic systems for the growth of agricultural plants. To this purpose, a liquid fraction [aqueous hydrothermal carbonization (HTC) liquid (AHL)] derived from HTC of cow manure digestate was chemically characterized (pH, electrical conductivity, mineral elements, and organic compounds such as phytotoxins), diluted with distilled water (1:30, 1:60, and 1:90, v/v) to reduce its potential phytotoxicity, and used to grow hydroponic maize (Zea mays L.) plants instead of the classical full-strength nutrient solution. The results indicated that the dilution ratio 1:30 of the AHL solution maintained a high level of toxicity for the plants (phytotoxic substances, especially Na and alkalinity), inducing the arrest of their growth. Differently, the two other dilution ratios (i.e., 1:60 and 1:90) seemed to considerably limit the levels of toxicity, since they allowed the plants to develop. However, these dilution ratios were poor in nutrient elements, inducing alteration in photosynthesis and an onset of deficiency symptoms such as pronounced leaf chlorosis. In view of an eco-friendly approach, future studies are, therefore, needed to identify the correct species-specific dilution ratio to supply both low levels of phytotoxins and adequate content of essential nutrients for appropriate plant growth and development. Furthermore, in order to lower specific Na phytotoxicity, treatments are of utmost importance before using AHL as a fertilizer solution.

Secondary metabolites and anti-microbial/anti-oxidant profiles in Ocimum spp.: Role of soil physico-chemical characteristics as eliciting factors

Ocimum has long been used as a medicinal plant, although little information is available about its bioactive ingredients, and the influence of soil properties on modulation of secondary metabolites in Ocimum has yet to be ascertained. In this study, we present a thorough survey of all potential metabolic compounds in O. sanctum and O. basilicum. In both species, certain compounds (e.g., quercetin, kaempferol, catechin, and S-adenosyl homocysteine) were detected coincidently. In the case of O. basilicum, other vital phenolic acids (e.g., ursolic, vanilic, coumaric, and syringic acids) were identified. The aqueous extracts (AEs) of Ocimum recorded decrease of 6-94% in the proliferation of pathogenic bacteria (e.g., Listeria monocytogenes, Staphylococcus sp., Salmonella sp., and Bacillus sp.). The AEs also showed effective antioxidant activity by reducing free radicals by a factor of 1.04-1.13. Root-zone soil samples of both Ocimum spp. were collected from strategic locations with varying levels of key soil attributes (e.g., soil organic carbon (SOC), microbial biomass carbon (MBC), urease, and phosphatase). At high levels of SOC, MBC, and soil enzymes, the bioactivity of Ocimum spp. was observed to be promoted, especially with respect to secondary metabolite expression, anti-pathogenic activity, and anti-oxidant properties. As such, the findings of strong correlations between secondary metabolite concentrations and bioactivity attributes in Ocimum suggest the potent role of soil quality in eliciting the production of secondary metabolite in association with bioactivity in Ocimum spp.

Allelopathy and its coevolutionary implications between native and non-native neighbors of invasive Cynara cardunculus L

Invasive plants apply new selection pressures on neighbor plant species by different means including allelopathy. Recent evidence shows allelopathy functions as remarkably influential mediator for invaders to be successful in their invaded range. However, few studies have determined whether native and non-native species co-occurring with invaders have evolved tolerance to allelopathy. In this study, we conducted germination and growth experiments to evaluate whether co-occurring native Juncus pallidus and non-native Lolium rigidum species may evolve tolerance to the allelochemicals induced by Cyanara cardunculus in Australian agricultural fields. The test species were germinated and grown in pots filled with collected invaded and uninvaded rhizosphere soil of C. cardunculus with and without activated carbon (AC). Additionally, a separate experiment was done to differentiate the direct effects of AC on the test species. The soil properties showed invaded rhizosphere soils had higher total phenolic and lower pH compared with uninvaded soils. We found significant reduction of germination percentage and seedling growth in terms of above- and belowground biomass, and maximum plant height and root length of native in the invaded rhizosphere soil of C. cardunculus, but little effect on non-native grass species. Even soil manipulated with AC showed no significant differences in the measured parameters of non-native except aboveground biomass. Taken together, the results indicate allelochemicals induced by C. cardunculus exert more suppressive effects on native than non-native linking the coevolved tolerance of those.

Comparing Machine Learning Models and Hybrid Geostatistical Methods Using Environmental and Soil Covariates for Soil pH Prediction

In the current paper we assess different machine learning (ML) models and hybrid geostatistical methods in the prediction of soil pH using digital elevation model derivates (environmental covariates) and co-located soil parameters (soil covariates). The study was located in the area of Grevena, Greece, where 266 disturbed soil samples were collected from randomly selected locations and analyzed in the laboratory of the Soil and Water Resources Institute. The different models that were assessed were random forests (RF), random forests kriging (RFK), gradient boosting (GB), gradient boosting kriging (GBK), neural networks (NN), and neural networks kriging (NNK) and finally, multiple linear regression (MLR), ordinary kriging (OK), and regression kriging (RK) that although they are not ML models, they were used for comparison reasons. Both the GB and RF models presented the best results in the study, with NN a close second. The introduction of OK to the ML models’ residuals did not have a major impact. Classical geostatistical or hybrid geostatistical methods without ML (OK, MLR, and RK) exhibited worse prediction accuracy compared to the models that included ML. Furthermore, different implementations (methods and packages) of the same ML models were also assessed. Regarding RF and GB, the different implementations that were applied (ranger-ranger, randomForest-rf, xgboost-xgbTree, xgboost-xgbDART) led to similar results, whereas in NN, the differences between the implementations used (nnet-nnet and nnet-avNNet) were more distinct. Finally, ML models tuned through a random search optimization method were compared with the same ML models with their default values. The results showed that the predictions were improved by the optimization process only where the ML algorithms demanded a large number of hyperparameters that needed tuning and there was a significant difference between the default values and the optimized ones, like in the case of GB and NN, but not in RF. In general, the current study concluded that although RF and GB presented approximately the same prediction accuracy, RF had more consistent results, regardless of different packages, different hyperparameter selection methods, or even the inclusion of OK in the ML models’ residuals.