Elevated Nutrient Levels Research Articles

Enhancing the phytoextraction capacity of chromium-contaminated soil by co-addition of garbage enzymes and microelectrolytic iron-carbon fillers

Most improved strategies for phytoextraction do not achieve a synergistic enhancement of chromium (Cr) accumulation capacity and biomass. This study investigated the impacts of co-addition of garbage enzyme (GE) and microelectrolytic iron-carbon filler (MF) on soil physicochemical properties, as well as form and uptake of Cr during aging and phytoextraction process. The response of rhizosphere microbial community to co-addition and its role in enhancing the remediation performance of ryegrass was further analyzed. Co-addition of GE and MF during the 12-day aging process resulted in an increase of nutrients, a shift from an oxidising to a reducing soil environment, a decrease of Cr(VI) content, and an enhancement of soil microbial community diversity and richness, creating a suitable environment for subsequent phytoextraction. During the 40-day phytoextraction process, co-addition played a crucial role in facilitating the establishment of a complex, efficient and interdependent ecological network among soil microorganisms and contributed to the evolution of microbial community composition and functional pathways. An increase in the relative abundance of Trichococcus, Azospirillum and g_norank_f_JG30-KF-CM45 elevated soil nutrient levels, while a decrease in the relative abundance of TM7a and Brucella reduced pathogen harbouring. Meanwhile, co-addition increased the relative abundance of Bacillus, Arthrobacter and Exiguobacterium, attenuated Cr phytotoxicity and improved soil biochemical activity. These markedly diminished oxidative damage and improved ryegrass growth by reducing malondialdehyde accumulation. In addition, regular additions of GE and the increase in relative abundance of norank_fnorank_o_Microtrichales led to rhizosphere acidification, which inhibited short-term Cr immobilization and contributed to a notable increase in phytoextraction efficiency. This study presents a strategy to enhance phytoremediation efficiency and soil quality during phytoextraction of Cr-contaminated soils.

Quantification and characterization of municipal solid waste at aler dumpsite, Lira City, Uganda: Assessing pollution levels and health risks

Managing municipal solid waste (MSW) in urban areas of developing countries is a significant challenge due to rapid urbanization and inadequate infrastructure. This study aims to quantify the MSW at Aler dumpsite in Lira City, Uganda, and assess the associated environmental and health risks. Our findings revealed a daily dumping rate of 7.38 tons, predominantly organic waste. Leachate from the site exceeded WHO limits for nutrients and heavy metals, with exceptionally high amounts of cadmium (Cd) found in soil (4.8 mg/kg) and vegetables. The water quality in nearby streams was poor, rendering it unfit for consumption due to elevated ion and nutrient levels. Health risk assessments indicated significant non-carcinogenic risks from heavy metal ingestion, with a hazard index (HI) of 4.6 for adults and 9.6 for children. While dermal exposure risks were generally low, children were at risk from stream 1 (HQderm = 1.165). Vegetable analysis revealed levels of lead (Pb), cadmium (Cd), zinc (Zn), and nickel (Ni) above safe doses, posing significant non-carcinogenic risks. To address these issues, we recommend increasing public awareness to avoid consuming water and vegetables from areas around the dump site. Additionally, we suggest that the responsible authorities improve MSW management by constructing sanitary landfills to minimize water, soil, and plant pollution from landfill leachate.

An Update on the Conservation Status Assessment of two Endangered Freshwater Mussel Species in Bavaria, Germany

ABSTRACTThe two highly endangered European mussel species Margaritifera margaritifera and Unio crassus are target species of conservation. Based on a recently completed systematic state‐wide monitoring of each 22 M. margaritifera and 22 U. crassus streams in Bavaria, Germany, we present an update on population trends, conservation status, habitat quality and threats for both species. Populations status and habitat quality varied strongly between M. margaritifera and U. crassus streams, but there was also great variability within each of those groups. The population decline of M. margaritifera has continued, albeit higher proportions of juveniles originating from artificial breeding programmes have been established in some streams. Habitat quality often did not match known requirements as evident from poor stream bed quality, lack of hosts and elevated nutrient levels. In contrast, U. crassus populations showed a better status, with an increase in population size over all sampled streams. Successful recruitment was indicated by high proportions of juveniles. However, no mussels older than 16 years were found, probably due to predation and structural stream maintenance measures. Climate change effects, such as extreme droughts, affected both species. This study demonstrates different needs in conservation management for both species. Although mitigation of drought effects is commonly needed for both species, tackling host fish management and direct threats such as predation should be prioritized in U. crassus, whereas restoration of prime habitat quality and intact catchments is key to enable natural recruitment and sustainable populations of M. margaritifera.

Nutrient-loaded seagrass litter experiences accelerated recalcitrant organic matter decay

High coastal nutrient loading can cause changes in seagrass chemistry traits that may lead to variability in seagrass litter decomposition processes. Such changes in decomposition have the potential to alter the carbon (C) sequestration capacity within seagrass meadows (‘blue carbon’). However, the external and internal factors that drive the variability in decomposition rates of the different organic matter (OM) types of seagrass are poorly understood, especially recalcitrant OM (i.e. cellulose-associated OM and lignin-associated OM), thereby limiting our ability to evaluate the C sequestration potential. It was conducted a laboratory incubation to compare differences in the decomposition of Halophila beccarii litter collected from seagrass meadows with contrasting nutrient loading histories. The exponential decay constants of seagrass litter mass, cellulose-associated OM and lignin-associated OM were 0.009–0.032, 0.014–0.054 and 0.009–0.033 d−1, respectively. The seagrass litter collected from meadows with high nutrient loading exhibited greater losses of mass (25.0–41.2 %), cellulose-associated OM (2.8–18.5 %) and lignin-associated OM (9.6–31.2 %) than litter from relatively low nutrient loading meadows. The initial and temporal changes of the litter nitrogen (N) and phosphorus (P) concentrations, stoichiometric ratios of lignin/N, C/N, and C/P, and cellulose-associated OM content, were strongly correlated with the losses of litter mass and different types of OM. Further, temporal changes of litter C and OM types, particularly the OM and labile OM concentrations, were identified as the main driving factors for the loss of litter mass and loss of different OM types. These results indicated that nutrient-loaded seagrass litter, characterized by elevated nutrient levels and diminished amounts of recalcitrant OM, exhibits an accelerated decay rate for the recalcitrant OM. These differences in litter quality would lead to a reduced contribution of seagrass litter to long-term C stocks in eutrophic meadows, thereby weakening the stability of C sequestration. Considering the expected changes in seagrass litter chemistry traits and decay rates due to long-term nutrient loading, this study provides useful information for improving C sequestration capabilities through effective pollution management.

Relative Expression of a Salinity Stress‐Responsive Na+/H+ Exchanger (NHX) in Root and Leaf Tissues of the African Leafy Vegetable, Amaranthus dubius

ABSTRACTAmaranthus dubius, an African leafy vegetable (ALV), is an easy‐to‐grow, annual shrub and a highly nutritious food source, containing elevated levels of essential nutrients in the leaves. Many ALVs, including A. dubius, can tolerate salinity stress, enabling their cultivation on marginal land. However, the widespread propagation of A. dubius as a stable food source has thus far not been realised due partially to the high frequency at which hybridisation occurs, resulting in high genotypic and phenotypic variability. Therefore, to increase the agricultural output capacity of this species on salt‐affected marginal lands, it is important to screen, select and then clonally propagate the identified salinity‐tolerant genotypes to ensure true‐to‐type fidelity in the regenerated population. It is also important, thereafter, to elucidate their underlying gene expression of the stress response. The present study exposed 4‐week‐old A. dubius seedlings to 100, 200 and 400 mM NaCl to determine their degree of salt tolerance. Genotypes were then screened, selected and clonally propagated through cuttings, based on high growth rates and biomass, and salt tolerance. Generally, growth and physiological parameters decreased as substrate salinity increased. However, individual salt‐stressed genotypes demonstrated similar vigour to nonstressed plants and were able to maintain total protein and chlorophyll concentrations despite increasing salinity. The relative expression of an NHX1‐like transcript was quantified in 15 genotypes using degenerately primed real‐time qPCR. The relative expression of the putative NHX1 gene was 6.7 times greater in root tissues of seedlings treated with 400 mM NaCl (10.7 ± 1.8) compared to the roots of untreated seedlings (1.6 ± 1.3), and 2.8‐fold more than leaf tissues harvested from seedlings treated with 400 mM NaCl. Furthermore, the relative electrical conductivity (EC) of root tissues was 10 times greater than the EC of leaf tissues from the same 400 mM NaCl treatment. Numerous genotypes yielded similar chlorophyll content between 200 and 400 mM NaCl treatments, with genotypes salinity‐1 (S1) (3.5 ± 0.2 μg/cm2) and S34 (4.0 ± 0.4 μg/cm2) having the highest concentrations of chlorophyll in the 400 mM group, which was positively correlated with total protein content. Following micropropagation through direct organogenesis, selected clones maintained true‐to‐type traits such as similar chlorophyll, protein and NHX1‐like expression as their parent plants when exposed to 400 mM NaCl. This study revealed that some genotypes demonstrated salt stress tolerance capabilities rivalling established halophytes by regulating the constitutive or inducible expression of an NHX1‐like protein in roots and leaves. The correlation between protein content and NHX1‐like expression was nonlinear and nonproportional, demonstrating the complexity of this response and necessitating further exploration of specific protein families or functional groups conferring salinity tolerance in this species.

Phytoplankton Diversity, Spatial Patterns, and Photosynthetic Characteristics Under Environmental Gradients and Anthropogenic Influence in the Pearl River Estuary.

The Pearl River Estuary (PRE) is one of the world's most urbanized subtropical coastal systems. It presents a typical environmental gradient suitable for studying estuarine phytoplankton communities' dynamics and photosynthetic physiology. In September 2018, the maximum photochemical quantum yield (Fv/Fm) of phytoplankton in different salinity habitats of PRE (oceanic, estuarine, and freshwater zones) was studied, revealing a complex correlation with the environment. Fv/Fm of phytoplankton ranged from 0.16 to 0.45, with taxa in the upper Lingdingyang found to be more stressed. Community composition and structure were analyzed using 18S rRNA, accompanied by a pigment analysis utilized as a supplementary method. Nonmetric multidimensional scaling analysis indicated differences in the phytoplankton spatial distribution along the estuarine gradients. Specificity-occupancy plots identified different specialist taxa for each salinity habitat. Dinophyta and Haptophyta were the predominant taxa in oceanic areas, while Chlorophyta and Cryptophyta dominated freshwater. Bacillariophyta prevailed across all salinity gradients. Canonical correlation analysis and Mantel tests revealed that temperature, salinity, and elevated nutrient levels (i.e., NO3--N, PO43--P, and SiO32--Si) associated with anthropogenic activities significantly influenced the heterogeneity of community structure. The spatial distribution of phytoplankton, along with in situ photosynthetic characteristics, serves as a foundational basis to access estuarine primary productivity, as well as community function and ecosystem health.

Effect of Different Planting Density in Cocoa (Theobroma cacao l.) on Leaf Macro and Micronutrient Levels Grown under Coconut Ecosystem

An experiment investigating the impact of different cocoa densities on leaf macro and micronutrient levels within a coconut ecosystem was conducted at the Coconut Farm of the Horticultural College and Research Institute, Tamil Nadu Agricultural University, Coimbatore. The study employed a Randomized Block Design (RBD) comprising eight treatments, each replicated three times. Notably, among the various spacing configurations, T1 (3m x 1.2m) exhibited the highest levels of leaf nitrogen (1.86%), phosphorus (0.084%), potassium (1.39%), and boron (91.33 ppm) content. This suggests that under Tamil Nadu conditions, high-density planting in the T1 treatment not only resulted in elevated nutrient levels but also correlated with a notable increase in revenue. These findings underscore the potential benefits of adopting high-density planting practices in cocoa cultivation within coconut ecosystems. Further research is warranted to explore the long-term implications of spacing configurations and nutrient interactions on crop productivity and profitability.

Land Use Impact on Water Quality and Phytoplankton Community Structure in Danjiangkou Reservoir

The composition and intensity of land use significantly influence the aquatic ecological environment, further affecting the physicochemical attributes of the water body, and indirectly modulating the phytoplankton community structure. This study centers around the Danjiangkou Reservoir, investigating the correlation between land use, water environment, and phytoplankton alongside varying intensities of anthropogenic activities, based on the review of land use, phytoplankton, and water quality data of 2021. Firstly, an analysis was conducted over five circular buffer zones generated around sampling points with radii set at 500 m, 1000 m, 1500 m, 2000 m, and 2500 m, wherein the intensity of human activity was categorized into low, medium, and high, in accordance with the human activity intensity level score (HAILS). This study proceeded to explore the correlation between land use and the water environment across different scales, compared phytoplankton density and community structure differences across varied levels of human activity, and analyzed the association between phytoplankton communities in the Danjiangkou Reservoir and environmental variables under various intensities. The findings showed: The land use within the 500 m circular buffer zone has the greatest impact on the water quality of the Danjiangkou Reservoir, especially with the increase in human activities leading to elevated nutrient levels in the water, thereby promoting the growth and reproduction of algae, and increasing the risk of algal blooms. This research scrutinizes the relationship between land use, water environment, and plankton under varying human activity intensities, serving as a foundation for environmental management sectors to make informed decisions and promote the sustainable development of the catchment water environment.

Long-term study of phytoplankton dynamics in a supply reservoir reveals signs of trophic state shift linked to changes in hydrodynamics associated with flow management and extreme events

This study analyses over a decade (2009–2022) of monitoring data to understand the impact of hydrological characteristics on water quality and phytoplankton dynamics in Prospect Reservoir, a critical water supply for Greater Sydney, Australia, known for its excellent water quality. Water quality and phytoplankton dynamics were related to hydrodynamics, linked to flow management and the water quality of inflows. Phytoplankton biovolume increased after a prolonged drawdown and subsequent refill event, mainly driven by dinoflagellates, and corresponded to increases in total phosphorus and water temperature. The hydrological period following the 2019/2020 summer bushfires (post-bushfire) that impacted connected reservoirs, was marked by increased flow activity and nutrient loading, leading to significant shifts in the phytoplankton community. Functional group classification and ordination analysis indicated a transition from taxa typically dominant in oligotrophic conditions to meso‑eutrophic. This transition correlated with elevated nutrient levels and chlorophyll-a (Chl-a), and reduced Secchi depth and dissolved oxygen, providing evidence of eutrophication. Q index indicated good water quality post-bushfire, contrasting with a eutrophic status assessment using Chl-a. Our findings highlight the importance of analysing long-term datasets encompassing varied hydroclimatological conditions for a deeper understanding of reservoir behaviour. A comprehensive approach to water quality assessment is recommended, combining functional group classification, Q index and Chl-a measurements for effective reservoir health assessment. This research provides novel insights into the effects of disturbances such as bushfires, on water quality and phytoplankton dynamics in an underrepresented geographic region, offering valuable knowledge for managing water resources amidst growing climate variability.

Potato Biofortification: A Systematic Literature Review on Biotechnological Innovations of Potato for Enhanced Nutrition

Potato biofortification is a comprehensive approach aimed at enhancing the nutritional content of potatoes, addressing widespread nutrient deficiencies and contributing to global food security. This systematic review examines the existing literature on various aspects of potato biofortification, encompassing genetic, agronomic, and biotechnological strategies. The review highlights the nutritional significance of potatoes, emphasizing their role as a staple food in many regions. Genetic approaches to biofortification involve the identification and use of natural variations in potato germplasm to develop varieties with elevated levels of essential nutrients. This includes targeting key micronutrients, such as iron, zinc, and vitamins, through traditional breeding methods. The review explores the genetic diversity within potato germplasm and the potential for breeding programs to develop nutrient-rich varieties. Agronomic practices play a crucial role in potato biofortification, with studies demonstrating the impact of tuber priming and the application of mineral fertilizers on nutrient concentrations in potatoes. The review delves into the intricacies of agronomic biofortification, emphasizing the importance of precise dosages and timing for optimal results. Biotechnological tools, including transgenic and non-transgenic approaches, are discussed in the context of potato biofortification. The review evaluates the efficiency and ethical considerations associated with the development of biofortified transgenic potatoes and emphasizes the significance of non-transgenic approaches in addressing consumer concerns and regulatory barriers. Overall, this systematic review provides a comprehensive overview of the current state of potato biofortification research. It synthesizes findings from diverse studies, offering insights into the potential of biofortified potatoes to address hidden hunger and contribute to improved nutritional outcomes. This review also identifies knowledge gaps and areas for future research, guiding the direction of efforts to harness the full potential of potato biofortification for global food and nutrition security.

The rhizosphere microbiome reduces the uptake of arsenic and tungsten by Blechnum orientale by increasing nutrient cycling in historical tungsten mining area soils

The growth of pioneer plants in metal mining area soil is closely related to their minimal uptake of toxic elements. Pioneer plants can inhibit the uptake of toxic elements by increasing nutrient uptake. However, few studies have focused on the mechanisms by which the rhizosphere microbiome affect nutrient cycling and their impact on the uptake of toxic elements by pioneer plants. In this study, we selected Blechnum orientale to investigate the potential roles of the rhizosphere microbiome in nutrient cycling and plant growth in a historical tungsten (W) mining area. Our results showed that while the arsenic (As) and W contents in the soil were relatively high, the enrichment levels of As and W in the B. orientale were relatively low. Furthermore, we found that the As and W contents in plants were significantly negatively correlated with soil nutrients (S, P and Mo), suggesting that elevated levels of these soil nutrients could inhibit As and W uptake by B. orientale. Importantly, we found that these nutrients were also identified as the most important factors shaping rhizosphere microbial attributes, including microbial diversity, ecological clusters, and keystone OTUs. Moreover, the genera, keystone taxa and microbial functional genes enriched in the rhizosphere soils from mining areas played a key role in nutrient (S, P and Mo) bioavailability, which could further increase the nutrient uptake by B. orientale. Taken together, our results suggest that rhizosphere microorganisms can improve pioneer plant growth by inhibiting toxic element accumulation via the increase in nutrient cycling in former W mining areas.

Investigating Temporal and Spatial Variations of Nutrient and Trace Metal Loading in Utah Lake (Utah, USA)

Utah Lake is one of the largest freshwater bodies in the West and a valuable resource for agricultural and recreational activities in the region. However, it has suffered elevated trace metal and nutrient levels since the pioneer settlement in 1847. The objectives of this project were as follows: (1) investigate the temporal and spatial variations of trace metal and nutrient concentrations in Utah Lake and its tributaries; (2) model trace metal and nutrient concentrations across the lake using GIS spatial analysis techniques. We collected floc layer sediment samples quarterly as well as monthly water samples for trace metal and nutrient analyses at designated sites. GIS spatial analysis techniques were used to model the trace metal and nutrient concentrations in the lake. Elevated trace metal concentrations in river and lake water samples have been detected, especially in the month of June. The GIS modeling revealed that the highest trace metal and nutrient concentrations were located at the deepest part of the lake and near the Spanish Fork River inlet, respectively. Moreover, the results indicate that Utah Lake is not well mixed horizontally but well mixed vertically. Our findings can help state agencies address issues in water quality and management related to human–environment interactions.

Wetland biodiversity of Ramaroshan Lake complex: a need for conservation

The Ramaroshan Lake Complex, situated in the mid-hills of Sudurpaschim Province, is renowned for its scenic beauty, yet there is a notable dearth of information regarding its biodiversity and ecological status. This study represents the first systematic examination of seasonal variations in water quality parameters and biodiversity encompassing aquatic macroinvertebrates, fishes, birds, herpetofauna, mammals, and macrophytes, as well as the surrounding vegetation within the complex, spanning the winters and summers of 2018 and 2019. Among the twenty water quality parameters investigated, thirteen displayed significant seasonal differences across the lakes (p <0.05), with Batula and Ramaroshan lakes exhibiting elevated nutrient levels. Lamadaya Lake stood out with a highly diverse macroinvertebrate community compared to other lakes, while overall, the study recorded 45 aquatic macroinvertebrate families, three fish species, 79 bird species, 12 herpetofauna species, 12 mammal species, and 26 macrophyte species within the complex. Additionally, the surrounding vegetation comprised 193 distinct plant species. Notably, the complex currently hosts 14 IUCN Red List species, including Near Threatened (5), Vulnerable (5), Critically Endangered (1), and Endangered (3) species, as well as five migratory wetland bird species, underscoring its significance for wildlife conservation. Given the diverse and cross-cutting nature of wetlands, the development of science-based policies and coordinated efforts among central, provincial, and local governments are essential for the preservation and sustainable management of these vital ecosystems.

Anthropogenic disturbances influence mineral and elemental constituents of freshwater lake sediments.

Lake sediments can provide valuable insights into anthropogenic disturbances such as intensive aquaculture and land use changes. These disturbances often manifest as elevated levels of nutrients and elements within the sediments. This paper uses several analytical techniques, i.e., FTIR (Fourier-transform infrared spectroscopy), XRD (X-ray diffraction), EDS (energy-dispersive X-ray spectroscopy), and SEM (scanning electron microscopy), to examine the elemental constituents of lake sediments, along with their relative mineral abundances and surface morphology. The selected freshwater lakes are from the Central Gangetic Plain. The analysis provides a "fingerprint" of geogenic and biogenic mineral constituents of the sediments. Physicochemical, mineralogical, and elemental analysis shows that intensive aquaculture activities in lake alter the sediment chemistry as evidenced by the increase in pH, organic carbon, organic matter, and total phosphorus which is not observed in the lake where aquaculture is prohibited. Freshwater lake sediment is characterized by a high content of biogenic silica and carbonate minerals. The variations in sediment nutrients and mineral fluxes of the selected lakes are mainly attributed to diverse anthropogenic pressures, differences in lake productivity, and the overall ecological condition of the lakes. In the selected three lakes, major variation was reported in the autochthonous sediments in comparison to the allochthonous sediments. The study concludes that catchment and biotic deposit variations in the lakes cannot be evened out by in-lake mixing mechanisms due to variations in the terrigenous and pelagic deposits of the lake. The results highlight the importance of studying annual fluctuations and spatial variations in geogenic and biogenic mineral particle fluxes in lakes. Such investigations provide valuable insights into the annual dynamics of minerals within lakes, contributing to a more comprehensive understanding of their behavior and distribution.

Impacts of Extratropical Cyclone Fiona on a sensitive coastal lagoon ecosystem

AbstractOceanic storms can strongly disturb the physical and biogeochemical conditions of transitional coastal waters. Impacts of extreme oceanic storms on coastal ecosystems have received limited attention worldwide, with no studies at higher latitudes (> 45°) where tropical cyclones have usually abated. This study investigates the combined impacts from marine and atmospheric forcing on a coastal lagoon in Prince Edward Island, Canada, during and after Extratropical Cyclone Fiona in September 2022. Physical (water levels and temperature) and biogeochemical (dissolved oxygen [DO], electrical conductivity, pH, nitrate–nitrogen concentrations, total suspended solids [TSS]) datasets from the lagoon and the watershed's tributaries, groundwater springs, and piezometers were used to assess ecosystem disturbance and recovery timelines following the storm. Fiona resulted in a 1.6 m storm surge into the lagoon that elevated water temperatures by up to 6°C, disturbed the density‐dependent stratification of salinity and temperature, and reduced the diel amplitude of DO, indicating a reduction in plant respiration due to ecosystem disturbance. The freshwater tributaries revealed sharp changes in flow (30‐fold increase), nitrate–nitrogen (NO3‐N) concentrations and loading (70‐fold increase), and TSS loading (40‐fold increase) to the lagoon during and immediately following the storm. The lagoon rapidly recovered (hours) from the hydraulic disturbance of the storm surge, but elevated nutrient levels persisted for months. The intensity and frequency of extratropical cyclones is projected to increase in the Northwest Atlantic, making field‐based studies of cyclone impacts on coastal waters critical for understanding future coastal ecosystem disturbance and recovery periods relative to the timing of future storms.

Herbivory and elevated levels of CO2 and nutrients separately, rather than synergistically, impacted biomass production and allocation in invasive and native plant species.

Large parts of the Earth are experiencing environmental change caused by alien plant invasions, rising atmospheric concentration of carbon dioxide (CO2 ), and nutrient enrichments. Elevated CO2 and nutrient concentrations can separately favour growth of invasive plants over that of natives but how herbivory may modulate the magnitude and direction of net responses by the two groups of plants to simultaneous CO2 and nutrient enrichments remains unknown. In line with the enemy release hypothesis, invasive plant species should reallocate metabolites from costly anti-herbivore defences into greater growth following escape from intense herbivory in the native range. Therefore, invasive plants should have greater growth than native plants under simultaneous CO2 and nutrient enrichments in the absence of herbivory. To test this prediction, we grew nine congeneric pairs of invasive and native plant species that naturally co-occurred in grasslands in China under two levels each of nutrient enrichment (low-nutrient vs. high-nutrient), herbivory (with herbivory vs. without herbivory) and under ambient (412.9 ± 0.6 ppm) and elevated (790.1 ± 6.2 ppm) levels of CO2 concentrations in open top chambers in a common garden. Elevated CO2 and nutrient enrichment separately increased total plant biomass, while herbivory reduced it regardless of the plant invasive status. High-nutrient treatment caused the plants to allocate a significantly lower proportion of total biomass to roots, while herbivory induced an opposite pattern. Herbivory suppressed total biomass production more strongly in native plants than invasive plants. The plants exhibited significant interspecific and intergeneric variation in their responses to the various treatment combinations. Overall, these results suggest that elevated CO2 and nutrients and herbivory may separately, rather than synergistically, impact productivity of the invasive and co-occurring native plant species in our study system. Moreover, interspecific variation in resource-use strategies was more important than invasive status in determining plant responses to the various treatment combinations.

Soil microbiota plays a key regulatory role in the outbreak of tobacco root rot.

Root rot caused by the fungal pathogen Fusarium sp. poses significant challenges to tobacco cultivation in China, leading to major economic setbacks. The interplay between this pathogen and the wider soil microbial community remains poorly understood. High-throughput sequencing technology was utilized to evaluate soil prokaryotic, fungal, and protistan communities. We compared microbial communities in infected soils to those in healthy soils from the same field. Additionally, the influence of pH on the microbial communities was assessed. Infected soils displayed elevated levels of soil nutrients but diminished observed richness across prokaryotic, fungal, and protistan groups. The pathogenic fungi Fusarium solani f sp. eumartii's abundance was notably increased in infected soils. Infection with F. solani significantly altered the soil's microbial community structure and interactions, manifested as a decrease in network scale and the number of keystone species. An evaluation of prokaryotes' role in F. solani's invasion revealed an increased number of connecting nodes in infected soils. Additionally, relationships between predatory protists and fungi were augmented, whereas predation on F. solani declined. The study underscores the significance of comprehending the interactions among soil microorganisms and brings to light the susceptibility of soil microbial communities to pathogen invasion. It offers insights into the multifaceted relationships and potential vulnerabilities within the soil ecosystem in the context of Fusarium sp. invasion.

Impact of varied NPK fertilizer application rates and seed quantities on barley yield and soil nutrient availability in chestnut soil of Azerbaijan

In the Gobustan district of Azerbaijan, the cultivation of barley is influenced by a complex interplay of soil properties, climate change effects, and agricultural practices. This study explores the impact of varying NPK fertilizer application rates and seed quantities, under natural climatic conditions, on barley yield and soil nutrient availability within Chestnut soils. The district's unique Chestnut soils, combined with evolving precipitation patterns due to climate change and the role of agricultural irrigation, create intricate challenges for successful barley farming. The experiment, conducted from 2016 to 2019, utilized a randomized complete block design with four replications to investigate the "Celilabad-19" barley variety. The results reveal a significant positive correlation between nitrogen application and grain yield. Notably, treatment 140-N60P45K45 (140 kg seed rate, 60 kg N/ha, 45 kg P/ha and 45 kg K/ha) demonstrated the highest average grain yield of 5.14 t/ha. The years 2017-2018 exhibited higher yields, possibly due to favorable climate conditions. Soil analyses indicated that higher NPK application rates led to elevated soil nutrient levels. However, nutrient content declined as plants progressed through growth stages, emphasizing the dynamic nutrient exchange between plants and soil. This study underscores the importance of adaptive agricultural strategies that consider climate variability and changing environmental conditions. The findings offer insights into sustainable cultivation practices essential for food security and crop production in the evolving climate of the Gobustan district.

The Effect of Far-Red Light and Nutrient Level on the Growth and Secondary Metabolites of the In Vitro Culture of Prunella vulgaris

Prunella vulgaris, a medicinal plant with antioxidant capacity, was investigated for its response to varying intensities of far-red light and nutrient levels. Plantlets were cultured for 30 d under low far-red light (LFR) or high far-red light (HFR) conditions and different nutrient levels (full, half, and quarter). HFR reduced leaf and branch number, dry weight, and accumulation of chlorophylls (Chl) and carotenoids (Car), while increasing plant height. Lower nutrient levels increased plant height and leaf number, but decreased branch number, Chl, and Car. HFR significantly increased total phenolic content (TPC), rutin, and rosmarinic acid levels, while total flavonoid content decreased. As nutrient levels decreased, TPC and rosmarinic acid declined. HFR induced significant DPPH scavenging activity, while reducing power increased with higher far-red light and nutrient levels. The ferrous ion chelating effect under LFR reduced with lower nutrient levels. There were strong correlations among TPC, rosmarinic acid, DPPH scavenging activity, and reducing power. In conclusion, HFR inhibited plantlet growth but enhanced secondary metabolite accumulation and antioxidant capacity. Different nutrient levels stimulated diverse growth responses, while elevated nutrient levels promoted secondary metabolite production. This study demonstrated the responses of growth, secondary metabolite accumulation, and antioxidant activity in the in vitro cultured P. vulgaris to supplemental far-red light and various nutrient levels.

Decadal evolution of an acidic pit lake: Insights into the biogeochemical impacts of microbial community succession

Acidic pit lakes represent hydrological features resulting from the accumulation of acid mine drainage in mining operations. Long-term monitoring is essential for these extreme and contaminated environments, yet tracking investigations integrating microbial geochemical dynamics in acidic pit lakes have been lacking thus far. This study integrated historical data with field sampling to track decadal biogeochemical changes in an acidic pit lake. With limited artificial disturbance, significant and sustained biogeochemical changes were observed over the past decade. Surface water pH slowly increased from 2.8 to a maximum of 3.6, with a corresponding increase in bottom water pH to around 3.9, despite the accumulation of externally imported sulfate and metals. Elevated nutrient levels stimulated the macroscopic growth of Chlorophyta, resulting in a shift from reddish-brown to green water with floating algal bodies. Furthermore, microalgae-fixed organic carbon promoted the transition from the initial chemolithotrophy-based population dominated by Acidiphilium and Ferrovum to a heterotrophic community. The increase in heterotrophic iron- and sulfate-reducers may cause an elevation in ferrous levels and a decline in copper concentrations. However, most metals were not removed from the water column, potentially due to insufficient biosulfidogenesis or sulfide reoxidation. These findings offer novel insights into microbial succession in extreme ecosystem evolution and contribute to the management and remediation of acidic pit lakes.