Biomass Accumulation Rate Research Articles

Partially Substituting Photosynthetic Photon Flux Density with Far-red Photons Differentially Alters Biomass Accumulation and Photochemical Efficiency of Greenhouse Lettuce

Adding far-red (FR) photons to a constant photosynthetic photon flux density (PPFD) alters photosynthesis, leaf morphology, and biomass accumulation of horticultural plants. However, the influences of partially substituting PPFD with FR photons under the same extended PPFD (ePPFD) on the growth of greenhouse lettuce (Lactuca sativa L.) is still unknown. In this study, loose-leaf lettuce (‘Dasusheng’) grown in a greenhouse in the fall was implemented using six supplementary light treatments including white plus red (WR) LEDs with substitutive FR photon flux density at 0, 10, 30, 50, 70, and 90 µmol·m−2·s−1 under the same ePPFD (WR139, WR129+FR10, WR109+FR30, WR89+FR50, WR69+FR70, and WR49+FR90, respectively). Lettuce grown with natural light only was designated as NL. The results indicated that supplementary light led to lower plant height, thicker leaves, higher biomass accumulation, higher vitamin C content, higher starch content, and higher total soluble sugar content in lettuce compared with those of lettuce grown under NL. Lettuce grown under WR139 resulted in a 40.0% decrease in plant height, 66.8% increase in leaf thickness, and 34.1% increase in shoot fresh weight compared with those of lettuce grown under NL. No significant differences were observed in leaf width, specific leaf area, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, soil plant analysis development value, apparent quantum yield, soluble protein content, and light use efficiency of lettuce among the WR139, WR129+FR10, and WR109+FR30 treatments. Furthermore, decreased trends were observed in the biomass accumulation and maximum net photosynthetic rate of lettuce with the increased substituted FR photon flux density. However, an opposite trend was found in the maximum photochemical quantum yield. In conclusion, partially substituting PPFD with FR photons at 10 to 30 μmol·m−2·s−1 had similar effects on the biomass accumulation and nutritional quality of greenhouse lettuce. The FR photons should be applied with the consideration of photon flux density because the results also demonstrated negative effects of excess substituted FR photons for PPFD.

Genome-Scale Metabolic Model Reconstruction and Investigation into the Fluxome of the Fast-Growing Cyanobacterium Synechococcus sp. PCC 11901.

The ability to convert atmospheric CO2 and light into biomass and value-added chemicals makes cyanobacteria a promising resource microbial host for biotechnological applications. A newly discovered fastest-growing cyanobacterial strain, Synechococcus sp. PCC 11901, has been reported to have the highest biomass accumulation rate, making it a preferred target host for producing renewable fuels, value-added biochemicals, and natural products. System-level knowledge of an organism is imperative to understand the metabolic potential of the strain, which can be attained by developing genome-scale metabolic models (GEMs). We present the first genome-scale metabolic model of Synechococcus sp. PCC 11901 (iRS840), which contains 840 genes, 1001 reactions, and 944 metabolites. The model has been optimized and validated under different trophic modes, i.e., autotrophic and mixotrophic, by conducting an in vivo growth experiment. The robustness of the metabolic network was evaluated by changing the biomass coefficient of the model, which showed a higher sensitivity toward pigments under the photoautotrophic condition, whereas under the heterotrophic condition, amino acids were found to be more influential. Furthermore, it was discovered that PCC 11901 synthesizes succinyl-CoA via succinic semialdehyde due to its imperfect TCA cycle. Subsequent flux balance analysis (FBA) revealed a quantum yield of 0.16 in silico, which is higher compared to that of PCC 6803. Under mixotrophic conditions (with glycerol and carbon dioxide), the flux through the Calvin cycle increased compared to autotrophic conditions. This model will be useful for gaining insights into the metabolic potential of PCC 11901 and developing effective metabolic engineering strategies for product development.

Optimizing biofuel production from algae using four-element framework: Insights for maximum economic returns

This paper introduces a Four Element Strategy (FES) focused on concentration of CO2 gas (Cc,g), energy input to the process, concentration of nutrients, and the type of algal strain to maximize biofuel production (BYP) from algae strains and evaluate associated economic benefits. Two algal strains encompassing slain algae Nannochloropsis sp. (Ns), and freshwater strain Chlorella vulgaris (Cv) were used in the current study. Response Surface Methodology (RSM) and Box Behnkin Design (BBD) are integrated with a biokinetic model to explore the relationships among growth parameters in the ranges; Cc,g ∼ 0.03–20 %), Nitrogen (N) to phosphorus (P) ratio (RN/P)∼1–11, and light intensity (LI)∼ 100–400 µE m⁻² s⁻¹ with corresponding CO2 bio-fixation rate (RCO2, g L⁻¹ d⁻¹), biomass accumulation (X, g L⁻¹), and algal growth rate (µ, d⁻¹). Optimization results indicate that the most productive conditions involve LI in the range of 100–270 µE m⁻² s⁻¹, Cc,g between 0.03 % and 15 %, and RN/P of 3.5–11, achieving maximum RCO2, X, and µ at 1 g L⁻¹ d⁻¹, 6 g L⁻¹, and 1.6 d⁻¹, respectively. Further optimization using the desirability function supports achieving RCO2 of 1.2 g L⁻¹ d⁻¹, X of 1.8 g L⁻¹, and µ of 1.7 d⁻¹, with RN/P, Cc,g, and LI at 11, 4.5 %, and 200 µE m⁻² s⁻¹, respectively. Notably, Ns demonstrated higher nutrient uptake rates and BYP compared to Cv, with total production costs of $0.629/L and respective required cost coverages of $0.138 and $0.375 for Ns and Cv. This study offers a comprehensive guideline for large-scale microalgae cultivation technology (MCT) processes, providing insights into optimizing conditions for biofuel production while considering economic viability.

Duckweed (Lemna minor D0158): a promising protein source for food security

Duckweeds, recognized as the fastest growing aquatic flowering plants, exhibit substantial biomass production. Recently, they have been emerged as a potential industrial crop for efficient and eco-friendly protein production and nutrient recovery compared to conventional crops. The objective of the study was to determine the biomass accumulation rate, protein content and amino acid analysis of duckweeds (Lemna minor D0158).We cultured L. minor D0158 from its preserved state in the gene bank into both aseptic (in-vitro) and open condition at controlled room. The medium was Hoagland Solution (HS) mixed with sucrose in in-vitro condition while 1/5 concentration of HS (without sucrose) was in the open condition. Subsequently, we determined the dry biomass growth by calculating the weight difference adopting the Bergmann Method, and then calculated the protein percentage following the Kjeldahl Method. Moreover, the amino acid profiling was obtained using the Hydrolysis and Liquid Chromatography Technique. Later on, we compared the results with those of the other duckweeds and soybean together with the FAO requirements. We found that L. minor D0158 possessed the dry biomass growth rate of 6.72 g/m2/d with 33.13% protein content within 7-day cultivation period. Moreover, it exhibited significantly higher levels of branched chain amino acids (BCCAs) than soybean and met the FAO requirements. However, methionine (Met) content was found to be slightly low. The study suggested that L. minor D0158 might offer a sustainable solution for protein food security in future.

Evaluation of Phytoremediation in the Ogoni Wasteland of Southern Nigeria

Phytoremediation offers an effective strategy for managing environmental degradation in the Ogoni wastelands of southern Nigeria, but its benefits and socio-economic implications have not been adequately studied. This study aims to investigate the effectiveness of phytoremediation techniques on soil contamination and community perception and participation in environmental restoration efforts. Soil samples were collected from several sites in Ogoni wasteland, and pollutant concentrations were analyzed by gas chromatography and mass spectrometry. Selected plant species were used for phytoremediation interventions, and microbial activity was assessed using CO2 production rates. Household surveys and interviews were conducted to measure perceptions of community membership and involvement in correctional programs. Analysis of soil samples revealed a significant decrease in contaminant concentrations after phytoremediation, with average initial concentrations decreasing to 23.456 mg/kg and plant biomass accumulation rates of 0.567 kg/sq m returning to 4.901 kg/m², an indication of differences in activity of various organisms in pollutant uptake. After phytoremediation, the changes showed an increasing trend, with CO2 emissions increasing from 0.567 mg CO2/g/hr to 1.345 mg CO2/g/hr. The household survey showed a positive attitude towards the effectiveness of phytoremediation, with an average score of 4.012 on a scale of 1 to 5. Research findings show that phytoremediation can be a sustainable solution for soil pollution in the Ogoni wastelands. These results contribute to the existing body of knowledge by providing empirical evidence and insights into the environmental, social, and economic dynamics of ecological restoration in conflict zones on the background.

A temperature-based model of biomass accumulation in humid forests of the world

Forests benefit humans in numerous ways. Many of these benefits are greater from forests with large trees and high biomass (i.e., above-ground biomass) than from young forests with small trees. Understanding how the biomass accumulation rate depends on climate is therefore important. According to a classic theory, the biomass accumulation rate first increases until canopy closure, as leaf area and gross primary productivity increase, and decreases thereafter because leaf area cannot increase further and maintaining larger biomass is energetically costlier as living tissue increases even though its proportion of all biomass decreases. We based our modeling on this classic theory and defined relative productivity, pr indicating productivity, and relative maintenance cost, cr, signaling the expense of sustaining a unit of biomass in humid climates of the world. The biomass accumulation rate of low biomass forests is determined by pr − cr and maximal biomass by pr/cr. We then compiled a global data set from the literature, with 3,177 records to fit a parameter for the efficiency of converting surplus carbon into accumulated biomass and another parameter determining biomass at canopy closure. Based on the parameterized models, a constant temperature of 22.3°C leads to the most rapid biomass accumulation in low biomass forests, whereas 16.4°C results in greatest maximal biomass. Our parameterized model can be applied to both climate change adaptation and mitigation by optimizing land use.

Giant sequoia (Sequoiadendron giganteum) in the UK: carbon storage potential and growth rates.

Giant sequoias (Sequoiadendron giganteum) are some of the UK's largest trees, despite only being introduced in the mid-nineteenth century. There are an estimated half a million giant sequoias and closely related coastal redwoods (Sequoia sempervirens) in the UK. Given the recent interest in planting more trees, partly due to their carbon sequestration potential and also their undoubted public appeal, an understanding of their growth capability is important. However, little is known about their growth and carbon uptake under UK conditions. Here, we focus on S. giganteum and use three-dimensional terrestrial laser scanning to perform detailed structural measurements of 97 individuals at three sites covering a range of different conditions, to estimate aboveground biomass (AGB) and annual biomass accumulation rates. We show that UK-grown S. giganteum can sequester carbon at a rate of 85 kg yr-1, varying with climate, management and age. We develop new UK-specific allometric models for S. giganteum that fit the observed AGB with r 2 > 0.93 and bias < 2% and can be used to estimate S. giganteum biomass more generally. This study provides the first estimate of the growth and carbon sequestration of UK open-grown S. giganteum and provides a baseline for estimating their longer-term carbon sequestration capacity.

Influence of Bradyrhizobium japonicum on the growth parameters and formation of the assimilation apparatus in E-gene isogenic lines of soybean

The study investigated the impact of the interaction between soybean and rhizobia on the assimilation apparatus functioning and biomass accumulation in different soybean lines with varying photoperiod sensitivity. Nearly isogenic lines (NILs) of soybean were used, with genes E1, E2, and E3 in different allelic states: Clark (e1E2E3), L80-5879 (E1e2e3), L63-3117 (e1e2E3), and L71-920 (e1e2e3). The experimental group for each line was treated with Bradyrhizobium japonicum 634b. Plants were grown under natural long-day conditions (16 hours). Growth indicators of the studied lines, such as relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), and specific leaf area (SLA), were analyzed, as well as the content of chlorophylls A and B in the V3 and V5 developmental stages. The results demonstrate that the influence of rhizobia on the functioning of the assimilation apparatus and biomass accumulation depends on the soybean line genotype. In the study, RGR, which characterizes the biomass accumulation rate, has similar trends to those observed with NAR, characterizing the assimilation apparatus's functioning. However, each line showed its own tendencies. For instance, in the short-day variety Clark, under bacterial influence, the value of RGR and NAR decreased. Additionally, LAR and SLA values indicated a reduction in the total photosynthetic surface area and leaf dry matter. Bacterial inoculation did not significantly affect the content of photosynthetic pigments in Clark leaves. Another short-day line, L80-5879, showed no significant impact of bacterial inoculation on biomass accumulation. However, soybean interaction with Bradyrhizobium japonicum 634b led to a decrease in leaf surface area and dry matter content. Probably, bacterial inoculation supported assimilation processes by increasing auxiliary chlorophyll b in photosystem I. A general trend of significant RGR reduction in neutral-day soybean lines, L63-3117 and L71-920, was identified under bacterial influence. The interaction with rhizobia differently affected LAR and SLA values, indicating distinct adaptive mechanisms to the interactions. In conditions of almost zero plant biomass accumulation, Bradyrhizobium japonicum 634b caused a decrease in the total photosynthetic surface area and chlorophyll a and b content in the L63-3117 line. In L71-920, bacterial inoculation had no effect on the total photosynthetic surface area, while leaf dry matter and photosynthetic pigment content decreased. The obtained results demonstrate that interaction with rhizobia can influence the functioning of the assimilation apparatus in soybeans with varying photoperiod sensitivity that is determined by genotype. It is important in improving soybean productivity and its application in agricultural practices.

Forest demography and biomass accumulation rates are associated with transient mean tree size vs. density scaling relations.

Linking individual and stand-level dynamics during forest development reveals a scaling relationship between mean tree size and tree density in forest stands, which integrates forest structure and function. However, the nature of this so-called scaling law and its variation across broad spatial scales remain unquantified, and its linkage with forest demographic processes and carbon dynamics remains elusive. In this study, we develop a theoretical framework and compile a broad-scale dataset of long-term sample forest stands (n = 1,433) from largely undisturbed forests to examine the association of temporal mean tree size vs. density scaling trajectories (slopes) with biomass accumulation rates and the sensitivity of scaling slopes to environmental and demographic drivers. The results empirically demonstrate a large variation of scaling slopes, ranging from -4 to -0.2, across forest stands in tropical, temperate, and boreal forest biomes. Steeper scaling slopes are associated with higher rates of biomass accumulation, resulting from a lower offset of forest growth by biomass loss from mortality. In North America, scaling slopes are positively correlated with forest stand age and rainfall seasonality, thus suggesting a higher rate of biomass accumulation in younger forests with lower rainfall seasonality. These results demonstrate the strong association of the transient mean tree size vs. density scaling trajectories with forest demography and biomass accumulation rates, thus highlighting the potential of leveraging forest structure properties to predict forest demography, carbon fluxes, and dynamics at broad spatial scales.

Morphological and physiological response of amphibious Rotala rotundifolia from emergent to submerged form.

Rotala rotundifolia is an amphibious aquatic plant that can live in submerged and emergent forms. It is superior in nitrogen and phosphorus removal. To elucidate its adaptation strategies from emergent to submerged conditions, phenotypic and physiological responses of R. rotundifolia were investigated during three months of submergence, at water levels of 0cm (CK), 50cm (W50), and 90cm (W90). Results showed that submergence stress reduced the relative growth rate of plant height, fresh weight, and biomass accumulation, leading to root degradation and a significant decline in the root-shoot ratio. The amounts of soluble protein (SP), soluble sugar (SS), and starch in the aerial leaves of W50 and W90 decreased during the early stages of submergence compared to CK, whereas the total chlorophyll and proline contents, and activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) increased. The contents of endogenous hormones, including abscisic acid (ABA), gibberellin (GA), and indole-3-acetic acid (IAA), decreased during the change in leaf shape; the decline in ABA was more obvious. The leaf primordium generated transition leaves and submerged leaves to resolve the "carbon starvation" of plants. The maximum values of non-structural carbohydrates (NSC) in the leaves of W50 and W90 occurred at day 30, reaching 14.0 mg g- 1and 10.5 mg g- 1, respectively. The contents of SP and starch, activities of SOD and CAT of the roots in submerged treatments increased, while SS and proline content decreased at day 7. These results demonstrated that developing heterophyllous leaves, increasing chlorophyll content, and regulating plant carbon allocation and consumption were important mechanisms of R. rotundifolia to adapt to underwater habitats.

Long-term biomass dynamics of temperate forests in Europe after cessation of management

Forests can contribute to climate change mitigation by sequestering carbon when management intensity is reduced. However, there is high uncertainty regarding biomass dynamics in temperate forests after the cessation of management. We used forest inventory data from an extensive network of 224 plots in 37 natural forest reserves (NFR) covering a wide environmental gradient with mean annual temperatures ranging from 1 to 10.4 °C and mean annual precipitation ranging from 901 to 2317 mm. Inventories had been conducted approximately every 10 years during the last 60 years. We used mixed effect models to (i) analyse biomass development, (ii) assess the role of time since the cessation of management (TSCM) and (iii) disentangle the environmental and forest structural drivers of biomass change. After the cessation of management and in the absence of high-severity natural disturbances, biomass accumulated gradually along a saturation curve. There were large differences in biomass among reserves and plots, with values ranging from 101 Mg ha−1 to 851.2 Mg ha−1, with a median of 362.1 Mg ha−1 (SD = 122.5 Mg ha−1). The biomass curve did not yet tend towards an equilibrium, most likely because the majority of the NFRs do not exceed 100 years of TSCM. Compared to higher elevations, forests at lower, warmer sites showed a larger total biomass and higher rates of biomass accumulation. We found a reduction by 148 Mg ha−1 of biomass per 1000 m of elevation gain. The strongest positive rate of change (>8 Mg ha−1 year−1) was found in forests with high basal area (>60 m2 ha−1) and medium to high levels of tree density (1500 to 2000 stems ha−1). Overall, most reserves have not reached a biomass equilibrium yet and continue to act as carbon sinks in tree biomass. This highlights the carbon sequestration capacity of forest reserves and their role as carbon pools.

Plant life history strategies vary in subtropical forests with different disturbance histories: an assessment of biodiversity, biomass, and functional traits.

Disturbance alters environmental conditions in forests. Plants growing in forests with different disturbance histories in diverse environments may adopt varying life history strategies, but few studies focus on this effect. This study comprehensively investigated plant biodiversity, biomass, and functional traits in subtropical forests with two different disturbance histories in east China to explore differences in life history strategies. Biodiversity was slightly higher in disturbed compared to conserved forests. Significantly higher biomass was measured in conserved relative to disturbed evergreen broadleaved forests (P < 0.05). In conserved forests, leaf tissue density (LTD) was significantly higher and leaf thickness (LT), leaf dry matter content (LDMC), twig tissue density (TTD), twig dry matter content (TDMC), bark tissue density (BTD) and dry matter content (BDMC), and stem tissue density (STD) and dry matter content (SDMC) were significantly lower than in disturbed forests (P < 0.05). In terms of associated plant biodiversity, biomass, and functional traits, conserved forests adopted a resource acquisition strategy, reducing biodiversity and developing multiple functional traits such as high leaf area and specific leaf area and low LT, LDMC, TTD, TDMC, BTD, BDMC, STD, and SDMC to support a high biomass accumulation rate. Disturbed forests adopted a resource conservation strategy, enhancing biodiversity and developing converse trait combinations to lower the rate of biomass accumulation. A comprehensive investigation of plant biodiversity, biomass, and functional traits and subsequent assessment of plant life history strategies in conserved and disturbed forests will aid investigations of regional biodiversity and carbon reserves, contribute data to the TRY and Chinese plant trait databases, and improve ecological management and restoration efforts in east China.

Analysis of rhizosphere fungal community of agricultural crops cultivated in laboratory experiments on Chernevaya taiga soil.

Chernevaya taiga of Western Siberia, Russia, is a unique ecosystem characterized by fertile soil, exceptionally large herbaceous plant sizes, and extraordinarily rapid rates of plant residue degradation. We expected that growing crops on soil collected from Chernevaya taiga, which has never been used for agricultural purposes before, would result in a distinct rhizospheric fungal community. This community could potentially yield novel, potent biostimulators and biocontrol fungi for modern agriculture. To check this idea, we used high-throughput ITS sequencing to examine the microbial communities in the rhizosphere of spring wheat and radish grown in greenhouse experiments on Chernevaya and control soils. Additionally, representative fungal strains were isolated and assessed for their ability to promote growth in wheat seedlings. The study revealed that the most abundant phyla in the rhizospheric fungal community were Mortierellomycota, primarily consisting of Mortierella species, and Ascomycota. Mucor and Umbelopsis comprised the majority of Mucoromycota in the control soils. Fusarium and Oidiodendron, two potentially plant-pathogenic fungi, were only found in the rhizosphere of crops grown in the control soil. Conversely, Chernevaya soil contained a diverse range of potential biocontrol fungi for plants. Tested novel fungal isolates showed a stimulating effect on the development of wheat seedlings and positively affected their rate of biomass accumulation. The results of the study demonstrate that the soil of Chernevaya taiga do indeed contain fungi with prominent potential to stimulate agricultural plants growth.

Impacts of climate change on semi-natural alpine pastures productivity and floristic composition

Climate change impact on pasture floristic composition needs to be carefully assessed, given its key role for the resilience of pastoral systems and related ecosystem services. Nevertheless, variations in floristic composition are rarely taken into account in climate change impact studies. Here, we used the plant community model CoSMo to simulate future dynamics of biomass accumulation and floristic composition for high-altitude semi-natural alpine pastures. Dedicated multi-site field activities were conducted to collect data for model calibration. Simulations were run for four 20-year climate scenarios centered on 2040, resulting from the combination of two general circulation models (GISS-ES and HadGEM2) and two representative concentration pathways (RCP4.5 and RCP8.5). Results highlighted the capability of CoSMo to successfully reproduce the productivity and floristic composition of semi-natural pastures, modeling efficiency and R2 being higher than 0.90 for aboveground biomass accumulation and relative abundance of species. CoSMo simulated an overall positive effect of increasing temperatures on pasture productivity (+ 10.7% on average), due to higher biomass accumulation rates and longer growing seasons. However, these benefits were highly heterogeneous among the monitored pastures (ranging from − 2.5 to + 16.2%), because of differences in floristic composition and in species-specific thermal requirements that led to complex, non-linear reactions to climate variations. A negative impact of climate change was simulated for grazing value (− 11.1% on average), due to the higher suitability to future conditions of Nardus stricta, which has low grazing value compared to other species. Our results highlight that floristic composition should be explicitly considered while assessing climate change impacts on semi-natural pasture productivity and connected ecosystem services.

Self-Powered and Self-Sensing Blue Carbon Ecosystems by Hybrid Fur Triboelectric Nanogenerators (F-TENG)

Seaweeds are critical in the blue carbon ecosystem; however, light limitation is a bottleneck for seaweed farming, especially in turbid waters. Utilizing triboelectric generators (TENG) to provide light for seaweeds is a promising solution for enhancing seaweed growth and increasing their carbon sequestration rate. Here, we develop the hybrid fur TENG (F-TENG) designed with the fur-brush TENG (FB-TENG) and fur-sphere TENG (FS-TENG) to enhance the growth of seaweeds and achieve the self-powered and self-sensing blue carbon ecosystems. The FB-TENG exhibits a multistage step signal response, enabling the determination of the fur brush's relative displacement, which, in turn, reflects the impact of marine flow on the device in the vertical direction. The FS-TENG is employed for marine flow energy harvesting in the horizontal direction to illuminate LED lights and stimulate seaweed growth. The FS-TENG with four power generation units achieves the peak current, transferred charge, and instantaneous output power values of 29.9 μA, 0.66 μC, and 89.3mW, respectively. The seaweed cultivation experiments are conducted to demonstrate the significantly enhanced performance of the self-powered and self-sensing blue carbon ecosystems with respect to the growth of the juvenile seaweed by using the hybrid F-TENG as a self-powered light supply. A remarkable increase is observed in both the average net biomass accumulation and linear growth rate, reaching up to 10.83 ± 0.16% day-1 and 9.12 ± 0.68% day-1, respectively. Eventually, experiments are conducted in a circulating water tank to showcase the remarkable energy harvesting capabilities of the hybrid F-TENG. The reported hybrid F-TENG provides a promising solution for establishing self-powered and self-sensing blue carbon ecosystems.

Use of Insect Exclusion Row Cover and Reflective Silver Plastic Mulching to Manage Whitefly in Zucchini Production.

The challenges that sweet potato whitefly (Bemisia tabaci) creates for vegetable production have increased in the southeastern U.S. Growers must use intensive insecticide spray programs to suppress extremely high populations during the fall growing season. Thus, the objective of this study was to evaluate the use of a reflective plastic mulch and an insect row cover as alternative methods to the current grower practices to manage whiteflies in zucchini (Cucurbita pepo) production. Field experiments were conducted with a two-level factorial experimental design of cover and plastic mulch treatments arranged in a randomized complete block design, with four replications in Georgia in 2020 and 2021, and in Alabama in 2021. Cover treatments consisted of an insect row cover installed on zucchini beds at transplanting and removed at flowering and a no-cover treatment, while plastic mulch treatments consisted of reflective silver plastic mulching and white plastic mulching. During all growing seasons, weather conditions were monitored, whitefly populations were sampled weekly, zucchini biomass accumulation was measured at five stages of crop development, and fruit yield was determined at harvesting. Warm and dry weather conditions early in the growing season resulted in increased whitefly populations, regardless of location and year. In general, the reflective silver plastic mulching reduced whitefly populations compared to the conventional white plastic by 87% in Georgia in 2020, 33% in Georgia in 2021, and 30% in Alabama in 2021. The insect row cover treatment reduced whitefly populations to zero until its removal. Consequently, zucchini plants grown with the insect row cover and reflective silver plastic mulching had an increased rate of biomass accumulation due to the lower insect pressure in all locations. Zucchini grown using silver reflective plastic mulch and row covers had an overall increase of 17% and 14% in total yield compared to white plastic mulch and no-cover treatments, respectively. Significant differences in yield among locations were likely due to severe whitefly pressure early in the fall season, and total yields in Georgia in 2020 (11,451 kg ha-1) were 25% lower than in Georgia in 2021 (15,177 kg ha-1) and in Alabama in 2021 (15,248 kg ha-1). In conclusion, silver plastic mulching and row covers reduced the whitefly population and increased biomass accumulation and total yield. These treatments can be considered ready-to-use integrated pest management practices for growers.

Copper reduces the virulence of bacterial communities at environmentally relevant concentrations

Increasing environmental concentrations of metals as a result of anthropogenic pollution are significantly changing many microbial communities. While there is evidence metal pollution can result in increased antibiotic resistance, the effects of metal pollution on the virulence of bacterial communities remains largely undetermined. Here, we experimentally test whether metal stress alters the virulence of bacterial communities. We do this by incubating three wastewater influent communities under different environmentally relevant copper concentrations for three days. We then quantify the virulence of the community phenotypically using the Galleria mellonella infection model, and test if differences are due to changes in the rate of biomass accumulation (productivity), copper resistance, or community composition (quantified using 16S amplicon sequencing). The virulence of the communities was found to be reduced by the highest copper concentration, but not to be affected by the lower concentration. As well as reduced virulence, communities exposed to the highest copper concentration were less diverse and had lower productivity. This work highlights that metal pollution may decrease virulence in bacterial communities, but at a cost to diversity and productivity.

Deep phosphorus fertilizer placement increases maize productivity by improving root-shoot coordination and photosynthetic performance

It’s well known that the development and distribution of roots could be regulated to obtain deep soil resource and enhance the grain yield by increasing the depth of fertilization, but little is known about whether increasing P fertilization depth can optimize the root distribution to delay leaf senescence, enhance photosynthetic performance and root-shoot coordination or not. We conducted a field experiment that tested the following four placement depths of P fertilization: 5 cm (P5), 10 cm (P10), 15 cm (P15), and 20 cm (P20). The experiment was designed to explore the regulatory effects of the P fertilization depth on the root growth and distribution, the photosynthetic performance, the root-shoot coordination, the yield formation, the N and P fertilizer utilization of maize plants. We found that deep P placement did indeed alter the root parameters. In the 20–60 cm soil layer, both the root dry weight and length of P15 treatment were on average 23.2% higher than those of P5 treatment. The specific root length and specific root surface area of P15 treatment were 4.5% and 5.6% higher than those of P5 treatment. In addition, the P15 treatment achieved a significantly improved photosynthetic performance over the P5 treatment: The leaf area index at the R6 stage was 10.2% higher, the leaf senescence index from the R2 to the R6 stages was 31.4% lower, the photosynthetic rate at the R3 stage was 25.9% higher. The P placement depth also optimized the root-shoot coordination: The ratios of root weight to shoot weight, root surface area to leaf area, and root length to leaf area of P15 treatment were 6.7%, 13.8%, and 12.7% higher than those of P5 treatment, respectively. Finally, the root P and N uptake efficiency, the photosynthetic P-use efficiency, and the physiological P-use efficiency of P15 treatment were all significantly higher than those of P5 treatments. And together these responses had the effect of increasing the mature biomass by 12.5%, and the grain yield by 22.0%. In conclusion, increasing the P fertilization placement depth to 15 cm regulates the growth and development of the root system, which in turn improves the capability of plant to uptake and utilize N and P in the soil, delays the onset of leaf senescence, enhances its photosynthetic performance and biomass accumulation rate, and thus ultimately increases the yield.

Exploring the functional connectivity between the Kis-Balaton Water Protection System and Lake Balaton using satellite data

Lake Balaton, a shallow polymictic freshwater lake in Central Europe, became eutrophic in the 1970s. To retain the inorganic nutrients from the main tributary River Zala, a semi-artificial system called the Kis-Balaton Water Protection System (KBWPS) was constructed in the early 1980s. In 2015, the system was reconstructed and modernised, thus offering the opportunity to evaluate the effectiveness of the functional connection between the KBWPS and Lake Balaton over the past 20 years and to compare its impact before and after the reconstruction. To this end, time series data of algal biomass in Lake Balaton between 1999 and 2019 based on Landsat 7 satellite data were analysed. Over the last 20 years, the algal biomass in Lake Balaton showed an increasing trend (0.009 ± 0.011% increase per year), with territorial specificities also observed. No change was noted in the western part, while an increase was recorded in the eastern part of the lake. A significant difference in the rate of algal biomass accumulation was noticed before (annual increase of 0.008 ± 0.019%) and after (0.240 ± 0.306% per year) the KBWPS reconstruction. Given that the largest increase in algal biomass after reconstruction was observed in the outermost KBWPS basin of Lake Balaton, it appears that mesoscale environmental, water balance, or other factors affecting the lake are playing a role in this increase, rather than the KBWPS reconstruction. This research highlights the potential to study aquatic ecosystems using Earth observation techniques, and how mesoscale factors such as changes in the local climate regime or shifts in lake management can greatly impact the trophic state of a large shallow lake. Effectively identifying these factors is crucial in maintaining the proper status of aquatic ecosystems.

Naturally aged polylactic acid microplastics stunted pakchoi (Brassica rapa subsp. chinensis) growth with cadmium in soil

Biodegradable microplastics (BMPs) and cadmium (Cd) are posing threats to agro-systems especially to plants and current studies mostly used virgin BMPs to explore their ecological effects. However, effects of naturally aged BMPs and their combined effects with Cd on pakchoi are yet to be unraveled. Therefore, this study incubated naturally aged polylactic acid (PLA) MPs through soil aging process and investigated the single and combined effects of Cd and PLA MPs (virgin and aged) on pakchoi (Brassica rapa subsp. chinensis) morphology, antioxidant systems and soil microbial activities. Our results found that after being deposited in soil for six months, aged PLA (PLAa) MPs formed with a fractured surface, demonstrating more detrimental effects on pakchoi than virgin ones. PLA/PLAa MPs and Cd stunted pakchoi growth, caused oxidative stress and altered the biophysical environment in soil, separately. Moreover, co-existence of PLA/PLAa MPs and Cd caused greater damages to pakchoi than applied alone. The co-presence of PLAa MPs and Cd inhibited pakchoi biomass accumulation rate by 92.2 % compared with the no-addition group. The results unraveled here emphasized BMPs, especially aged BMPs, could trigger negative effects on agro-systems with heavy metals. These findings will give reference to future holistic assessments of BMPs' ecological effects.