Seed Germination Index Research Articles

Plant Adaptability to Improved Dredged Sediment

Traditional dredged sludge disposal methods are characterized by low resource utilization and high carbon emissions, leading to serious environmental pollution. This study used dredged sludge, composted pig manure, and sawdust as raw materials, and supplemented them with composite biological agents to prepare improved soil. Plant adaptability to the improved soil was comprehensively evaluated using factors such as seed germination index (GI). The alkaline nitrogen content in the improved soil increased by 78.61% compared to the dredged sludge, and the content of other nutrients such as available potassium also increased to varying degrees. Ryegrass seed GI increased by 51.06% in improved soil (IS1) compared to dredged sludge. The main dominant fungi in the improved soil (IS1) were Tausonia, Trichoderma, and Cystoflobasidium, which promote soil nutrient activation and antagonize pathogenic bacteria, making the environment more conducive to plant growth. Dredged sludge was successfully converted into planting soil. Fully utilizing the nitrogen, phosphorus, and other substances enriched in dredged sludge to provide nutrients for plant growth is an efficient method to achieve dredged sludge resource utilization.

Enhanced effect of ferrous sulfate on nitrogen retention and PBAT degradation during co-composting by combing with biochar-loaded FN1 bacterial composites.

The treatment of biodegradable plastics through composting has garnered increasing attention. This study aimed to investigate the effects of Biochar FN1 bacteria and ferrous sulfate on nitrogen retention, greenhouse gas emissions, and degradable plastics during composting and to elucidate their synergistic mechanisms on microbial communities. Compared with the control, applying biochar-loaded FN1 bacteria composites combined with Ferrous sulfate (SGC) markedly accelerated organic matter degradation and reduced cumulative CO2 and NH3 emissions. The synergistic interaction between the composites and Ferrous sulfate significantly enhanced NH4+-N levels in the thermophilic phase and NO3--N levels in the cooling phase, ultimately decreasing nitrogen loss by 14.9% (P<0.05) and increasing the seed germination index (GI) by 22.5% (P<0.05). Additionally, PBAT plastic degradation was improved by 31.6% (P<0.05). The SGC treatment also altered the richness and diversity of the bacterial community in both the compost and the PBAT plastic sphere, particularly affecting Sphingobacterium, Pseudomonas, and Flavobacterium at the genus level. Symbiotic network analysis and Redundancy Analysis revealed that these functional degradation bacteria were significantly positively correlated with NO3--N levels and PBAT degradation. Furthermore, structural equation modelling indicated a positive relationship between PBAT degradation rate and composting temperature (r=0.69, p<0.05). The findings suggested that Fe2+ not only enhanced the FN1 activity but also promoted PBAT degradation by increasing ·OH content on the PBAT plastic sphere. Overall, the combined use of biochar-loaded FN1 bacteria and Ferrous sulfate effectively supports nitrogen retention and plastic degradation during composting.

Role of Bioavailability in Compost Maturity During Aerobic Composting of Chicken Manure

To evaluate the effects of the type and proportion of bulking agents on compost maturity, chicken manure feedstock (J) was selected as the main raw material for aerobic composting, and wood chips (M), straw (S), and cornmeal (Y) were used as bulking agents. The ratios of chicken manure feedstock to the three bulking agents were set at 1:3, 1:1, and 3:1, respectively. The compost mixture composed of wood chips (M) and feedstock (J) in a 1:1 ratio exhibited the highest temperature (75 °C). The treatment with a bulking-agent-to-feedstock ratio of 3:1 exhibited the lowest temperature (52 °C) and the longest high-temperature period (about 10 days). Moreover, the compost mixture composed of wood chips (M) and feedstock (J) in a 3:1 ratio exhibited the highest seed germination index (1.32), while the GI values for all cornmeal treatments did not meet the standard requirements (0.4). The predominant microorganisms in all three treatments included Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria. The total carbon transformation-related microorganism abundance in MJ31, SJ31, and YJ31 was 1.65%, 10.69%, and 3%, respectively. Further analysis showed that the bioavailability of feedstock was strongly correlated with compost maturity. The treatment with a bulking-agent-to-feedstock ratio of 3:1, with the highest GI, also exhibited the highest bioavailability. These results can guide the selection of the appropriate bulking agent and the optimal bulking-agent-to-feedstock ratio, offering a new direction for the optimization of the composting process.

Assessment of Textile Waste Circularity through Composting Using the Seed Germination Index as Indicator for a Sustainable Management

Assessment of Textile Waste Circularity through Composting Using the Seed Germination Index as Indicator for a Sustainable Management

Design and Testing of a Small-Scale Composting Facility for Sheep Manure Utilizing Aeration and Thermal Treatment

Inner Mongolia has the largest sheep population among China’s provinces, resulting in the production of a substantial amount of sheep manure. If left untreated, this manure can contribute to environmental pollution. However, sheep manure serves a dual purpose: it can be both a pollutant and a valuable source of organic fertilizer. Consequently, there is an urgent need to address the environmental issues arising from manure accumulation and its unused status. In this paper, a viable solution is proposed: the conversion of manure into fertilizer through a composting unit incorporating high-temperature aerobic fermentation technology. This unit, tailored for small farms and individual farmers, integrates critical functions such as ventilation, heating, and turning. Additionally, it boasts excellent thermal insulation, enhancing composting efficiency and enabling precise control over fermentation conditions. This design mitigates heat loss and accelerates maturation, addressing common challenges in traditional composting. The design process encompassed both equipment construction and control systems, with a primary focus on compost fermentation and aeration heating. The components were carefully designed or selected based on theoretical analysis and subsequently validated using simulation software, including EDEM and Fluent. The control system seamlessly integrates a touch screen interface, PLC programming, and control circuits to manage air pumps and electric heaters in response to changes in temperature and oxygen concentration. Furthermore, it controls the motors during the recovery phase. A comprehensive performance evaluation was conducted, revealing notable improvements. Under artificially heated conditions, the maximum temperature of the compost increased by approximately 20 °C, the composting cycle was reduced by roughly 4 days, and the seed germination index (GI) rose by about 9% when compared to natural fermentation. Thus, this device significantly accelerates composting and improves fertilizer quality by increasing the decomposition rate.

Screening and Evaluation of Salt-Tolerant Wheat Germplasm Based on the Main Morphological Indices at the Germination and Seedling Stages.

The successful screening and evaluation of salt-tolerant germplasm at the germination and seedling stages is of great importance for promoting the breeding of wheat varieties with salt tolerance. In this study, 70 wheat varieties bred in different regions were evaluated for salt tolerance through hydroponic exposure to different concentrations of salt. The relative water absorption, water absorption rate, dehiscence rate, germination rate, and germination index of seeds, and plant height, root length, stem diameter, and biomass of seedlings were determined at the germination and seedling stages of wheat, and the salt tolerance was identified and evaluated using multivariate statistical analysis. The germination ability and seedling growth potential of wheat germplasms decreased with the aggravation of salt stress. Based on the comprehensive salt tolerance index at the germination stage, our study identified 35 varieties to be salt-tolerant. There were nine varieties further screened for having strong salt tolerance according to the comprehensive salt tolerance index at the germination and seedling stages. SN41, Emam, YN301, and JM262 were superior in salt-tolerance, and YM39, LM30, JM60, YN999, and SD29 were salt-tolerant. Our study suggests that the biomass of seedlings can be used as a key parameter for assessing wheat germplasm's ability to withstand salt. Our results can provide some basic materials for cultivating new germplasm with salt tolerance and excavating the related genes of wheat.

Unraveling the impact of intervention strategies and oxygen disparity in humification during domestic waste composting

This study constructs three different photovoltaic assisted composting systems to treat rural domestic waste, and explores the interaction pathways between biomacromolecules and other factors under oxygen disparity at gradient heights of the compost. The optimized mode of regular turning and ventilation-dehydration significantly reduced the moisture content by 53.6% and increased the seed germination index by 35.6%. The oxygen content at different heights under the optimized mode significantly affects the physicochemical properties of the compost, and the degradation of cellulose, hemicellulose, and protein in the middle is higher than other parts. The structural equation model shows that the physicochemical properties at the bottom are affected by biomacromolecules, which may be related to volatile fatty acids(VFAs) produced under low oxygen conditions.The research results show that using manual turning and ventilation-dehydration as the optimized process can promote compost maturity, and oxygen concentration has an important impact on the humification process of the compost.

Plant growth regulators improve the yield of white lupin (Lupinus albus) by enhancing the plant morpho-physiological functions and photosynthesis under salt stress

BackgroundWhite lupin (Lupinus albus L.) is a multi-purpose, climate resilient, pulse crop with exceptionally high protein content that makes it a suitable alternative of soybean in livestock feed. Although white lupin grows well on marginal sandy soils, previous studies have reported its sensitivity towards salinity stress. This experiment aims to assess the influence of salinity stress and mitigating role of plant growth regulators (PGRs) on performance of white lupin.MethodologyThe white lupin plants were sown in pots maintained at three salinity levels (1, 3 and 4.5 dS m− 1) throughout the growing season and foliar sprayed with different PGRs, including ascorbic acid, potassium chloride, boric acid, ammonium molybdate and methionine at sowing, four weeks after emergence and at the initiation of flowering. Foliar spray of distilled water and salinity level of 1 dS m− 1 were maintained as control treatments. Data were recorded for seed germination indices, plant growth, antioxidant enzymes and photosynthetic efficiency variables.ResultsThe severe salinity stress (4.5 dS m− 1) reduced the germination indices by 9–50%, plant growth traits by 26–54%, root nodulation by 12–26%, grain development by 44–53%, antioxidant enzymes activity by 13–153% and photosynthetic attributes by 1–8% compared to control (1 dS m− 1). Different PGRs improved several morpho-physiological attributes in a varied manner. The application of potassium chloride improved seed vigour index by 53%, while ascorbic acid improved root nodulation by 12% and number of pods per cluster by 75% at the severe salinity level. The foliar application of PGRs also displayed a recovery of 140% in the activity of superoxide dismutase and 70% in catalase. The application of multi zinc displayed an improvement of 37% in plant relative chlorophyll, while ascorbic acid brought an increase of 25% in non-photochemical quenching and 21% in photochemical quenching coefficient at the severe salinity level. On contrary, the application of PGRs brought a relatively modest improvement (8–13%) in quantum yield of photosystem II at slight to moderate (3 dS m− 1) salinity stress. The correlation analysis confirmed a partial contribution of leaf area and seed vigour index to overall photosynthetic efficiency of white lupin.ConclusionsClearly, salinity exerted a negative impact on white lupin through a decline in chlorophyll content, activity of antioxidant enzymes and efficiency of photosynthetic apparatus. However, PGRs, especially ascorbic acid and potassium chloride considerably improved white lupin growth and development by mitigating the negative effects of salinity stress.

Microbiota of spring wheat seeds grown within the contrasting agroclimatic conditions of the Tyumen region

Relevance. Pathogenic microbiota of seed grain can cause death of seedlings, root rot, weakening of plants and a decrease in yield. Monitoring of seed grains pathogens infection rate is always relevant because the composition of the microbiota is dynamic due to the influence of natural and anthropogenic factors.Methods. Phytopathological analysis of spring wheat seeds grown at the state variety testing sites of the Tyumen region was carried out in contrasting years: cool and excessively moist in July 2015 and hot with moderate rainfall in 2016. We used the “wet chamber” method. 144 samples were analyzed.Results. Fungus of the genus Alternaria were the most abundant representatives of the grain microbial community. Average infection rate of seed samples with fungi Alternaria spp. was 49.5%. No differences were found by year of the study. In 2015 compared to 2016, higher prevalence of fungus of the genus Fusarium (4.8% vs. 1.6%) and bacteria (5.7% vs. 0.7%) was observed in the seed material. The maximum indicators of Fusarium infestation were observed in samples from Nizhnetavda variety testing site located in the subtaiga zone – up to 30% (variety Ikar). In 2016 compared to 2015, higher infection of seed material with helminthosporiose (7.1% vs. 2.6%) and mold fungi (2.3% vs. 0.2%) was observed. The prevalence of Bipolaris sorokiniana fungi was the highest in wheat samples grown in the northern forest-steppe zone, especially samples from the Yalutorovsky variety testing site — the limit value was 27% (variety SKENT-3). Harmfulness fungus of the genus Alternaria was significantly lower compared to other key representatives of grain microbiota. The average score of seedling damage was 1.4 vs. 2.2–2.6, seed germination indices — 94.1% vs. 53.2–67.4%.

Germination of soybean seeds after low-temperature storage and its dependence on weather and climate conditions in the places of reproduction of accessions

Background. Soybean (Glycine max (L.) Merr.) is a microbiotic whose seeds quickly lose germination in uncontrolled conditions at room temperatures. This determines the need to preserve accessions in special conditions. Low temperature storage (LTS) allows to maintain high seed germination ability, but not for all accessions. Therefore, it is relevant to assess the results of LTS at the VIR Genebank and to make an attempt to determine the best geographical conditions for growing plants and harvesting seeds that will be subjected to LTS. Materials and methods. The work was carried out on 312 soybean accessions from the VIR collection, originating from almost the entire area of soybean cultivation. The accessions used in the research were reproduced at three VIR experiment stations (ES), namely Adler ES, Kuban ES (Krasnodar Territory) and the Far East ES (Primorsky Territory). The seeds were harvested in 1999 to 2017 and stored in sealed foil laminated bags at –10°C from 2002 to 2021. The accessions were removed from LTS and germination assessed in 2022. Results. At the beginning of LTS, seed germination (Gi) ranged from 12 to 100% (averaging 79.1%), while that after LTS (Gr) ranged from 1 to 97% (57.8% on average). The retention of germination ability was expressed as the germination index (GI = Gr / Gi), which ranged from 0.02 to 1.73 (an average of 0.72). All the indicators of germination in the range of up to 20 years of LTS were not associated with the duration of LTS and with the number of years before LTS (0.5-4 years in our research). The climatic conditions characteristic of the place of reproduction had a significant impact on Gi and Gr, but not on GI. The average Gi of seeds obtained at the Adler ES and Kuban ES did not differ significantly (77.4% and 75.7%), while that of seeds harvested at the Far East ES was significantly higher (84.0%). Gr of the accessions from the Far East ES (64.3%) was also greater than that of accessions from the Kuban ES (52.2%) and Adler ES (57.2%). The excessively high sum of temperatures above 10°C (recorded in some years at all stations) reduced Gi, Gr but had little effect on GI. The highest values of Gi, Gr, and GI were demonstrated by the accessions maturing in 101-120 days. Additionally drying of the most late-ripening accessions (later than 140 days) in sheaves under an awning yielded seeds with high germination ability and good LTS tolerance. Conclusion. The seeds from different places of reproduction of accessions differed in germination before and after LTS, and, on an average, the highest values were demonstrated by the seeds harvested at the Far East ES, where the temperature regime is closer to the optimal one for soybeans. The seed germination index showed relative independence from the conditions of reproduction of accessions, including the climate and weather conditions, as well as the initial germination ability and LTS duration.

Exploring Plant Growth-Promoting Traits of Endophytic Fungi Isolated from Ligusticum chuanxiong Hort and Their Interaction in Plant Growth and Development.

Endophytic fungi inhabit various plant tissues and organs without inducing evident disease symptoms. They can contribute positively to the growth of plants, bolster plants resilience to environmental and biological stresses, and facilitate the accumulation of secondary metabolites. These microbial resources possess significant developmental and utilization value in various applications. Hence, this study focused on exploring the plant growth-promoting (PGP) traits of 14 endophytic fungi from Ligusticum chuanxiong Hort (CX) and elucidating the effects and mechanisms that facilitate plant growth. According to PGP activity evaluation, the majority of strains demonstrated the capacity to produce IAA (78.57%), siderophores (50.00%), ammonia (35.71%), potassium solubilization (21.43%), nitrogen fixation (57.14%), and phosphate solubilization (42.86%). Further investigations indicated that the levels of IAA ranged from 13.05 to 301.43 μg/mL, whereas the soluble phosphorus levels ranged from 47.32 to 125.95 μg/mL. In cocultivation assays, it was indicated that Fusarium sp. YMY5, Colletotrichum sp. YMY6, Alternaria sp. ZZ10 and Fusarium sp. ZZ13 had a certain promoting effect on lateral root number and fresh weight of tobacco. Furthermore, ZZ10 and ZZ13 significantly enhanced the germination potential, germination index, and vigor index of tobacco seeds. The subsequent potted trials demonstrated that the four endophytic fungi exhibited an enhancement to growth parameters of tobacco to a certain extent. ZZ10 and ZZ13 treatment had the best promotion effect. Inoculation with YMY5 increased the chlorophyll a and total chlorophyll content. ZZ10 and ZZ13 treatment remarkably increased the net photosynthetic rate, soluble sugars and soluble protein content, catalase and peroxidase activities, and lowered malondialdehyde content in tobacco leaves. In addition, YMY5 remarkably elevated superoxide dismutase activities. ZZ13 upregulated the expression of growth-related gene. Among them, ZZ13 had a better growth-promoting effect. In conclusion, these endophytic fungi possessing multi-trait characteristics and the capacity to enhance plant growth exhibit promising potential as biofertilizers or plant growth regulators.

Effects of temperature and drought stress on the seed germination of a peatland lily (Lilium concolor var. megalanthum).

Sexual reproduction through seeds is an effective way to renew plant populations and increase their genetic diversity, but seed germination process is complicated and relatively difficult due to the restriction of environmental conditions. Wetland plants that reproduce sexually through seeds may be affected by changes in moisture and temperature. This study aims to explore the ecological adaptation strategies of seed germination of Lilium concolor var. megalanthum under different hydrothermal conditions. Controlled experiments were conducted to investigate the germination performance of L. concolor var. megalanthum seeds at different temperatures (10°C, 15°C, 20°C, 25°C, and 30°C) and simulated drought stress conditions using PEG-6000 solutions (0%, 5%, 10%, 15%, and 20%). The results showed that temperature, drought stress, and their interaction significantly affected the days to first germination, germination percentage, coefficient of germination rate, germination energy, germination index, and vigor index of seeds (p<0.01). The germination percentage, germination index, and vigor index of seed were significantly higher at 25°C compared to other temperatures (p<0.01). The interaction between low temperature and drought stress significantly delayed the days to first germination. The inhibition of drought stress on seed germination was enhanced by PEG-6000 solution under high temperature. Under the conditions of 25°C and 5% PEG-6000 solution concentration, seeds of L. concolor var. megalanthum exhibited optimal germination parameters. At 10°C and 15°C, the seeds exhibited the highest tolerance to PEG-6000-simulated drought stress. Rehydration germination results showed that extreme temperatures and drought stress conditions inhibit seed germination of L. concolor var. megalanthum without damaging seed structure. The germination pattern of seeds under variable temperature and drought stress conditions reflects their adaptive strategies developed over long-term evolution to cope with the environmental conditions.

Co-composting of food waste and leaves as a way to improve soil microbial activity and green-gram growth

Mixtures of vegetable waste and leaves were used to prepare compost in piles. The carbon/nitrogen ratios of the biomass varied among the selected agricultural waste. Co-composting was carried out for six weeks with a starter culture. The organic matter of the leaves declined after four weeks of composting, and a stable compost was obtained after 42 days of composting. The compost temperature reached its maximum after 12 days and moisture content declined continuously up to 42 days. The pH value of the compost increased slowly during composting and reached a maximum after six weeks. The electrical conductivity of the compost was suitable for plant nutrition. The organic matter, as organic carbon, declined, and organic nitrogen was increased. The carbon/nitrogen ratio of the mature compost was decreased. The decreased levels of carbon/nitrogen ratio reflected the maturity of the compost. The organic matter (%) was maximum (&gt;50%) before composting process and it decreased gradually. The seed germination index was higher after 42 days of composting. The compost-treated plant improved yield and green gram seeds showed the presence of antioxidant enzymes.

Enhancing compost quality through biochar and oyster shell amendments in the co-composting of seaweed and sugar residue

Aquaculture and agricultural production generate substantial amounts of waste, including seaweed (which has plant-stimulating properties), oyster shells, and sugar residues. Through composting and appropriate management, these wastes have the potential to be converted into beneficial soil amendments. However, there is a lack of research exploring the potential of composting in promoting the conversion of seaweed into more stable humified forms, as well as in assessing whether composted seaweed retains its beneficial effects on plant growth. Additionally, studies on using oyster shells as additives to reduce waste pressure and comparing their effectiveness with biochar are relatively scarce. This study examines the impact of incorporating 5% corn stover biochar (T1), 10% biochar (T2), and 10% oyster shell powder (T3) on key physicochemical properties, product quality, and microbial community dynamics during the co-composting of seaweed and sugar residues. Results indicate that organic matter (OM) loss in T1 and T2 increased by 31.2% and 26.4%, respectively, compared to the control (CK). Moreover, Excitation-emission matrix (EEM) fluorescence spectroscopy revealed that humic substances in T1 and T2 surged by 434% and 423%, respectively, far exceeding the 289% increase in CK. The 10% biochar treatment also improved alginate degradation and seed germination index, due to the presence of biostimulants in seaweed and an increased abundance of Cobetia. Microbial analysis post-composting showed that T2 and T3 significantly enhanced the diversity and richness of bacterial communities. Notably, although oyster shell powder did not improve the humification degree of compost as significantly as biochar, it achieved effective weight reduction of waste (OM loss of 43.57%, far exceeding CK's 35.34%) without hindering the composting process. All four compost treatments retained the plant-stimulating effects of seaweed and facilitated alginate degradation. These results underscore the potential of biochar to enhance composting efficiency and utilize composting to process large quantities of oyster shell waste.

Impact of Microplastics on the Carbon and Nitrogen of Vermicompost

ABSTRACTThe impact of microplastics (MPs) on carbon (C) and nitrogen (N) content in vermicompost is not yet fully understood. This study aims to evaluate the effect of MPs on the carbon and nitrogen ratio in vermicompost, which is important for soil quality and health. The study was carried out using a control treatment and six variations of MPs in the vermicomposting process. Observations were carried out at certain time intervals for 60 days with routine measurements of pH, electrical conductivity (EC), seed germination index (GI), survival rate (SR), and C/N ratio. The results showed that all types of MPs caused a decrease in the C/N ratio compared to the control, with the high‐density polyethylene (HDPE) MPs treatment showing the most significant decrease (from 21 to 9.42). Observations also showed that MPs had an impact on reducing the SR parameters (6.88%–20.41%), pH (6.8–6.1), and EC (525.3–398 µs/cm) in vermicompost, which had an impact on the final product quality thereby reducing the GI (10%–28%). MPs have a significant effect on the C/N ratio in vermicompost, reducing the quality of the compost. This study provides new insights into how MPs can affect the composting process and the quality of the final product, important for sustainable agricultural practices and waste management.

Investigation of the Composting Process of Mongolian Horse Manure Utilizing Intelligent Composting Equipment

The Inner Mongolia Autonomous Region, known for its famous Mongolian horses, faces significant environmental challenges due to the large-scale rearing of these animals, which produces a substantial amount of manure. If not managed effectively, this manure can lead to severe environmental pollution. The aim of this study was to investigate whether a small-scale intelligent aeration and heating composting system is effective in treating Mongolian horse manure, with the objective of enhancing composting efficiency and resource utilization to support sustainable agricultural development in the region. The equipment was utilized to treat a compost mixture of Mongolian horse manure and corn stover, allowing for an analysis of the changes in key indicators throughout the composting process. The results demonstrated that the equipment maintained high temperatures for up to eight days during the composting process, effectively inactivating pathogens and promoting the efficient decomposition of organic matter. The system also successfully controlled humidity to 12.7% and maintained oxygen concentration within the optimal range. Post-composting analysis revealed that the final compost contained 2.3% nitrogen, 1.3% phosphorus, and 1.2% potassium, with a pH of 6.4 and conductivity of approximately 5.2 mS/cm. Additionally, the carbon-to-nitrogen ratio decreased significantly from 27.3 to 15.9, indicating substantial organic matter degradation. Seed germination tests showed germination rates of 80%, 86%, and 75% for corn, mung bean, and wheat, respectively, with a final seed germination index of 104%. This study concluded that the small aeration and heating composting equipment is highly effective in treating Mongolian horse manure, producing high-quality organic fertilizers that significantly enhance soil fertility and demonstrate considerable potential for supporting sustainable agricultural practices and improving environmental management in the Inner Mongolia Autonomous Region.

The Physiological Mechanism of Exogenous Melatonin on Improving Seed Germination and the Seedling Growth of Red Clover (Trifolium pretense L.) under Salt Stress.

Salt stress can affect various physiological processes in plants, ultimately hindering their growth and development. Melatonin (MT) can effectively resist multiple abiotic stresses, improving plant stress resistance. To analyze the mechanism of exogenous MT to enhance salt tolerance in red clover, we conducted a comprehensive study to examine the influence of exogenous MT on various parameters, including seed germination indices, seedling morphological traits, and physiological and photosynthetic indicators, using four distinct red clover varieties (H1, H2, H3, and H4). This investigation was performed under various salt stress conditions with differing pH values, specifically utilizing NaCl, Na2SO4, NaHCO3, and Na2CO3 as the salt stressors. The results showed that MT solution immersion significantly improved the germination indicators of red clover seeds under salt stress. The foliar spraying of 50 μM and 25 μM MT solution significantly increased SOD activity (21-127%), POD activity, soluble sugar content, proline content (22-117%), chlorophyll content (2-66%), and the net photosynthetic rate. It reduced the MDA content (14-55%) and intercellular CO2 concentration of red clover seedlings under salt stress. Gray correlation analysis and the Mantel test further verified that MT is a key factor in enhancing seed germination and seedling growth of red clover under salt stress; the most significant improvement was observed for NaHCO3 stress. MT is demonstrated to improve the salt tolerance of red clover through a variety of mechanisms, including an increase in antioxidant enzyme activity, osmoregulation ability, and cell membrane stability. Additionally, it improves photosynthetic efficiency and plant architecture, promoting energy production, growth, and optimal resource allocation. These mechanisms function synergistically, enabling red clover to sustain normal growth and development under salt stress.

Evaluation of the quality of products from multiple industrial-scale composting treatment facilities for kitchen waste and exploration of influencing factors

The aerobic composting process is extensively utilized to manage kitchen waste. Nonetheless, the variability in the quality of compost derived from engineering practices which significantly hinders its broader industrial application. This work investigated the final products of kitchen waste compost at multiple industrial-scale treatment facilities utilizing three distinct aerobic composting processes in a bid to explore key factors affecting compost quality. The quality evaluation was based on technical parameters like seed germination index (GI), and limiting factors such as heavy metal content. The results showed that most of the compost products failed to meet the established standards, with GI being the primary limiting indicator. Furthermore, maturity assessments suggested that compost with low GI exhibited reduced humification could not be recommended for agricultural use. The investigation delved into the primary determinants of GI, focusing on risk factors such as the oil and salt of kitchen waste, and the microbial community of the humification driving forces. The results indicated that products with low GI had higher oil and salt content and a relatively simple microbial community. A thorough analysis suggested that excessive levels oil and salt were potential influencing factors on GI, as they stimulated the activity of acid-producing bacteria like Lactobacillus, suppressed the activity of humification-promoting bacteria such as Actinomarinales, and influenced the decomposition and humification processes of organic matter and total nitrogen, thereby affecting product quality. The findings provide valuable insights for improving kitchen waste compost products for agricultural applications.

Microbial electrochemical enhanced composting of sludge and kitchen waste: Electricity generation, composting efficiency and health risk assessment for land use

To realize the energy and resource utilization from organic solid waste, a two-phase microbial desalination cell (TPMDC) was constructed using dewatered sludge and kitchen waste as the anode substrate. The performance of electricity generation and composting efficacy was investigated, along with a comprehensive assessment of the potential health risks associated with the land use of the resulting mixed compost products. Experimental outcomes revealed a maximum open-circuit voltage of 0.893 ± 0.005 V and a maximum volumetric power density of 0.797 ± 0.009 W/m³. After 90 days of composting enhanced by microbial electrochemistry, a significant organic matter removal rate of 31.13 ± 0.44 % was obtained, and the anode substrate electric conductivity was reduced by 30.02 ± 0.04 % based on the anode desalination. Simultaneously, there was an increase in the content of available nitrogen, phosphorus, and potassium, as well as an improvement in the seed germination index. The forms of heavy metals shifted from bioavailable to stable residual states. The non-carcinogenic hazard index (HI) values for heavy metals and polycyclic aromatic hydrocarbons (PAHs) during the land use of compost products were less than 1, and the total carcinogenic risk (TCR) values for heavy metals and PAHs were below the acceptable threshold of 10−4. The occupational population risk of infection from five pathogens was higher than that of the general public, with all risk values ranging from 8.67 × 10−8 to 1, where the highest risk was attributed to occupational exposure to Legionella. These outcomes demonstrated that the mixture of dewatered sludge and kitchen waste was an appropriate anode substrate to enhance TPMDC stability for electricity generation, and its compost products have promising land use suitability and acceptable land use risk, which will provide important guidance for the safe treatment and disposal of organic solid waste.

Co-composting of dewatered sludge and wheat straw with newly isolated Xenophilus azovorans: Carbon dynamics, humification, and driving pathways

Composting is a biological reaction caused by microorganisms. Composting efficiency can be adequately increased by adding biochar and/or by inoculating with exogenous microorganisms. In this study, we looked at four methods for dewatered sludge waste (DSW) and wheat straw (WS) aerobic co-composting: T1 (no additive), T2 (5% biochar), T3 (5% of a newly isolated strain, Xenophilus azovorans (XPA)), and T4 (5% of biochar-immobilized XPA (BCI-XPA)). Throughout the course of the 42-day composting period, we looked into the carbon dynamics, humification, microbial community succession, and modifications to the driving pathways. Compared to T1 and T2, the addition of XPA (T3) and BCI-XPA (T4) extended the thermophilic phase of composting without negatively affecting compost maturation. Notably, T4 exhibited a higher seed germination index (132.14%). Different from T1 and T2 treatments, T3 and T4 treatments increased CO2 and CH4 emissions in the composting process, in which the cumulative CO2 emissions increased by 18.61–47.16%, and T3 and T4 treatments also promoted the formation of humic acid. Moreover, T4 treatment with BCI-XPA addition showed relatively higher activities of urease, polyphenol oxidase, and laccase, as well as a higher diversity of microorganisms compared to other processes. The Functional Annotation of Prokaryotic Taxa (FAPROTAX) analysis showed that microorganisms involved in the carbon cycle dominated the entire composting process in all treatments, with chemoheterotrophy and aerobic chemoheterotrophy being the main pathways of organic materials degradation. Moreover, the presence of XPA accelerated the breakdown of organic materials by catabolism of aromatic compounds and intracellular parasite pathways. On the other hand, the xylanolysis pathway was aided in the conversion of organic materials to dissolved organics by the addition of BCI-XPA. These findings indicate that XPA and BCI-XPA have potential as additives to improve the efficiency of dewatered sludge and wheat straw co-composting.