Soil Traits Research Articles

Responses of Legume‐Associated Rhizobacterial Communities to Plant Diversity and Soil Traits in Alpine Grassland

ABSTRACTLegume species are essential components of plant diversity and affect soil biodiversity across various ecosystems. Their effect on the diversity and traits of soil bacteria, particularly in degraded grasslands, remains unknown. This study analysed the relationships among plant diversity, soil traits and legume‐associated rhizobacterial communities in Xiahe (XH) and Maqu (MQ) in Gansu Province, Haibei (HB) in Qinghai Province and Hongyuan (HY) in Sichuan Province in the eastern Qinghai‐Tibetan Plateau (QTP). The diversity index values (coverage, richness, Shannon index and evenness) of legume species were positively correlated with plant diversity. Several soil nutrients (ammonia‐nitrogen, nitrate‐nitrogen, total nitrogen, available potassium, available phosphorus and soil organic matter) and enzymes (urease, sucrase, peroxidase and dehydrogenase) were lower in HB and HY than in XH and MQ. The Shannon index for rhizobacterial diversity was higher in HB and HY than in XH and MQ. In contrast, the diversity index values were higher for geographical locations than for sympatric plant species. Additionally, HB and HY showed 50% fewer positive and negative associations with rhizobacteria than XH and MQ. Functional Annotation of Prokaryotic Taxa analysis indicated a higher relative abundance of nitrate reduction occurred in HB and HY than in XH and MQ, whereas nitrogen fixation occurred at a lower level in HB and HY than in XH and MQ. The Simpson index value for bacterial diversity was positively correlated with plant diversity, legume species diversity and soil multifunctionality. However, the Shannon index value was negatively correlated with these parameters. Changes in the composition of legume‐associated rhizobacteria across different geographical locations are strongly influenced by plant diversity and soil nutrients, reflecting the distribution characteristics of legumes in alpine grasslands.

Fertilizer reduction and biochar amendment promote soil mineral-associated organic carbon, bacterial activity, and enzyme activity in a jasmine garden in southeast China

Reducing chemical fertilizers and biochar amendment is essential for achieving carbon neutrality, addressing global warming, and promoting sustainable agricultural development. Biochar amendment, a carbon rich soil additive produced through biomass pyrolysis, enhances soil fertility, increases crop yield, and improves soil carbon storage. However, research on the combined effect of fertilizer reduction and biochar amendment on soil mineral associated organic carbon (MAOC) in jasmine gardens is limited. This study aims to determine if biochar can reduce industrial fertilizer usage without compromising soil quality. This study focuses on jasmine cultivation in southeastern China, employing four treatments: conventional fertilization (CK), biochar amendment without fertilizer (BA), fertilizer reduction (FR), and fertilizer reduction with biochar amendment (FRBA). The effects on MAOC, microbial abundance, and enzyme activity were investigated. The FRBA treatment significantly increased MAOC content by 19.98 % compared to CK (P < 0.05). The BA and FRBA treatments enhanced the diversity of soil bacteria, including Lactobacillus, Azospirillum, and Cutibacterium, which are associated with soil organic carbon sequestration and nutrient decomposition. The RandomForest model identified β-N-acetyl-glucosaminidase (NAG), electric conductivity (EC), β-1, 4-Glucosidase (BG), soil potential of Hydrogen (pH), soil bulk density (BD), and β-D-cellobiosidase (CBH) as key soil traits promoting MAOC accumulation (P < 0.05). The results indicate that BA and FRBA improve soil bacterial community structure, enzyme activity, and MAOC content, promoting soil carbon accumulation through environmental factors and dominant bacteria. This study encourages future fertilization protocols that enhance fertilizer efficiency and carbon storage in crop soils.

Investigating the influence of eco-friendly approaches on saline soil traits and growth of common bean plants (Phaseolus vulgaris L.).

Soil salinization significantly impacts agricultural lands and crop productivity in the study area. Moreover, freshwater scarcity poses a significant obstacle to soil reclamation and agricultural production. Therefore, eco-friendly strategies must be adopted for agro-ecosystem sustainability under these conditions. A study conducted in 2022 and 2023 examined the interaction effects of various soil mulching materials (unmulched, white plastic, rice straw, and sawdust) and chitosan foliar spray application (control, 250 mg L-1 of normal chitosan, 125 mg L-1 of nano chitosan, and 62.5 mg L-1 of nano chitosan) on the biochemical soil characteristics and productivity of common beans in clay-saline soil. Higher organic matter, available nutrient content, and total bacteria count in soils were found under organic mulching treatments (rice straw and sawdust). In contrast, the white plastic mulching treatment resulted in the lowest values of soil electrical conductivity (EC) and the highest soil water content. Conversely, chitosan foliar spray treatments had the least impact on the chemical properties of the soil. Plants sprayed with 62.5 mg L-1 of nano chitosan exhibited higher chlorophyll content, plant height, fresh weight of shoots and roots, seed yield, and nutrient content compared to other chitosan foliar spray applications. All treatments studied led to a significant reduction in fungal communities and Na% in plants. The combined effect of organic mulch materials and foliar spray application of 62.5 mg L-1 nano chitosan appeared to enhance biochemical saline soil properties and common bean productivity.

Soil Traits and Grapevine Rootstock Genotypes Modulate Arbuscular Mycorrhizal Rate and Species in a Mediterranean Environment

The soil microbiota is a key component of agroecosystems, and understanding its traits is crucial for effective agronomic management. Among beneficial microorganisms, arbuscular mycorrhizal fungi (AMFs) are mutually associated with grapevine (Vitis vinifera L.), enhancing the ability of this cropping system to adapt to soil conditions and bolstering its resistance and resilience against abiotic stresses, particularly drought, by promoting root growth and enhancing the roots’ absorption surface. The objective of this on-field study was to determine AMF species richness and diversity along with their relation to soil chemical, physical, and biological characteristics in two adjacent organic vineyards in Central Italy. The two tested vineyards of the autochthonous cv. Aleatico differed by the presence of grafted (Vitis berlandieri × V. riparia rootstock; AL-420) or own-rooted (ungrafted V. vinifera L.; AL-ORV) vines. To this aim, soil and root samples were collected and geo-referenced. Analysis of the AMF species colonizing roots of both AL-ORV and AL-420 revealed the presence of four species: Scutellospora alterata, Paraglomus laccatum, Acaulospora laevis, and A. baetica, with S. alterata being the most frequent. Mycorrhization parameters were higher in the roots of grafted plants compared to ungrafted ones. A high beta-glucosidase (BG):N-acetylglusosaminidase (NAG) ratio in two tested vineyards indicated that microbes utilized more cellulose than chitin and peptidoglycan as dominant C resources. A negative correlation between mycorrhization rate (MyCP) and BG was observed, likely because AMFs form mutualistic relationships with plants, depending on the host plant for carbon. Results revealed a positive correlation between the degree of mycorrhizal association and the species involved, with the presence of copper and nickel among metals. Negative correlations were found concerning soil clay content along with beta-glucosidase. In conclusion, the grapevine root system was characterized by a differential symbiotic relationship with AMF species, whose development is influenced by the root genotype, soil texture, and biochemistry. Specifically, the increased frequency of AMFs in relation to copper content strengthens the evidence of their role in maintaining a vine’s production capacity in the event of soil contamination by this element.

Assessing the impact of organic resources and phosphorus on nutrient uptake, soil traits and seed potato productivity

AbstractImproving tuber yield size to boost seed potato (Solanum tuberosum) production efficiency is a paramount goal, particularly in Punjab, India, a major contributor to the nation's seed supply. To optimize nutrient absorption, soil quality, and yield of seed‐sized tubers, research was conducted in Ludhiana and Jalandhar over two years. Employing a split‐plot design, three organic treatments (farmyard manure [FYM], biofertilizer, control) were tested in main plots, while five phosphorus fertilizer levels (46.9, 62.5, 93.8, 125, 0 kg ha−1 P2O5) were examined in subplots. Results revealed that FYM notably enhanced nitrogen, phosphorus, and potassium uptake in both haulm and tubers compared to other organics. Moreover, higher phosphorus levels, particularly 125 kg ha−1 P2O5, maximized nutrient uptake. Soil attributes like available nitrogen remained unaffected, whereas phosphorus availability increased with FYM and higher phosphorus levels. Available potassium remained consistent across treatments. Soil pH, electrical conductivity, and organic carbon were unchanged with 125 kg ha−1 P2O5 treatments. FYM and biofertilizer significantly increased total tuber yields, with FYM showing a remarkable 30% boost compared to the control, and 125 kg ha−1 P2O5 phosphorus levels resulting in a notable 24% increase, indicating enhanced seed potato production strategies. Principal component analysis underscored the positive correlation between tuber yield and soil attributes, particularly favoring FYM and 125 kg ha−1 P2O5 treatments. Overall, FYM application and optimal phosphorus fertilizer levels are pivotal for augmenting nutrient uptake, soil health, and yield in seed potato cultivation.

Alpine meadow and alpine steppe plant-soil network in Qinghai-Tibet Plateau, China

Alpine meadow and alpine steppe are crucial ecosystem types in the Qinghai-Tibet Plateau. However, due to ecosystem fragility and human disturbance, the nutrient imbalance between plant and soil leads to grassland degradation. From a systematic perspective, there needs to be a comprehensive understanding of the plant and soil traits within these two ecosystem types. This study addressed this gap by constructing plant-soil trait networks for alpine meadow and alpine steppe, identifying bridge traits, and comparing the stability and distinctions of the two trait networks. The results demonstrated a significant difference in the distribution of network structure edge weights between the alpine meadow and steppe. In the network of alpine meadow, the soil organic carbon was responsible for linking plant and soil traits, exhibiting the highest impact. Conversely, the network of alpine steppe revealed an increasing negative correlation between plant and soil traits. The results of bridge traits agreed with the optimal distribution hypothesis. The bridge traits of the alpine meadow were aboveground traits (AGB or PlantC), while those of the alpine steppe were belowground traits (BGB and RootN). Based on our findings, different management measures could be taken. The alpine meadow could be primarily restored through natural processes, and climate warming would enhance its carbon sequestration capacity. The alpine steppe ecosystem exhibits low nitrogen availability, which could be augmented through fertilisation or the return of yak manure.

Rotary Tillage Plus Mechanical Transplanting Practices Increased Rice Yields with Lower CH4 Emission in a Single Cropping Rice System

As the main contributor to greenhouse gas (GHG) in paddy soil, information on methane (CH4) emission characteristics under different tillage and cultivation practices are limited. A five-year field trial was conducted from 2019 in a single-cropping rice system in Taihu Lake region, east of China. The experiment had a completely randomized block design, and the treatments included rotary tillage plus rice dry direct seeding (RD), rotary tillage plus rice mechanical transplanting (RT), and plowing tillage plus rice mechanical transplanting (PT). We determined the rice yield, GHG emission, soil traits, and methanogens and methanotrophs in 2022 and 2023. The results revealed that PT and RT significantly increased rice yield compared to RD, whereas PT simultaneously increased CH4 emissions. The year-averaged cumulative CH4 emissions in PT were increased by 38.5% and 61.4% higher than RT and RD, respectively. Meanwhile, yield-scaled global warming potentials (GWPs) in RT and RD were lower than those in PT. Tillage and cultivation practices shifted mcrA and pmoA abundances, and PT significantly decreased pmoA abundance. The community structure and diversity of the methanogens and methanotrophs were not significantly affected. Structural equation model analyses illustrated that CH4 emissions were regulated by mcrA and pmoA directly, which in turn, regulated by soil carbon and nitrogen. Overall, rotary tillage plus mechanism transplanting was a feasible agronomic technology in a single-cropping rice system in Taihu Lake region, exhibiting higher and more stable rice productivity, accompanied with lower CH4 emissions and yield-scaled GWP.

Soil-plant-gall relationships: from gall development to ecological patterns.

The adaptive nature of the galler habit has been tentatively explained by the nutrition, microenvironment, and enemy hypotheses. Soil attributes have direct relationships with these three hypotheses at the cellular and macroecological scales, but their influence has been restricted previously to effects on the nutritional status of the host plant on gall richness and abundance. Herein, we discuss the ionome patterns within gall tissues and their significance for gall development, physiology, structure, and for the nutrition of the gallers. Previous ecological and chemical quantification focused extensively on nitrogen and carbon contents, evoking the carbon-nutrient defence hypothesis as an explanation for establishing the plant-gall interaction. Different elements are involved in cell wall composition dynamics, antioxidant activity, and regulation of plant-gall water dynamics. An overview of the different soil-plant-gall relationships highlights the complexity of the nutritional requirements of gallers, which are strongly influenced by environmental soil traits. Soil and plant chemical profiles interact to determine the outcome of plant-herbivore interactions and need to be addressed by considering not only the soil features and galler nutrition but also the host plant's physiological traits. The quantitative and qualitative results for iron metabolism in gall tissues, as well as the roles of iron as an essential element in the physiology and reproduction of gallers suggest that it may represent a key nutritional resource, aligning with the nutrition hypothesis, and providing an integrative explanation for higher gall diversity in iron-rich soils.

Combined Effect of Potassium Fertiliser, Saline Irrigation Water and Humic Acids On Soil Acidity and Yield Components of Pepper (Capsicum annuum L)

A field experiment was conducted to adapt seedlings of sweet pepper, also called “California Wonder”, to salinity and the role of humic acid and potassium fertiliser in reducing the effect of salinity on the plant. A three-factorial field experiment was conducted according to the Complete Random Block Design, with three replications during the spring season of 2018 to study the humic acid and potassium fertiliser role in enhancing the salt tolerance of pepper plants. The first factor included four levels of saline water irrigation, namely 2, 4, 6 and 8 dS.m-1. The second factor included a foliar application of three levels of humic acids i.e., 0, 25 and 50 kg.h-1. The third factor represents the addition of three levels of potassium fertiliser (potassium sulphate of 50% K2O according to the fertiliser recommendation of 0, 75 and 150 kg. h-1. The considered plant and soil traits were branch per plant, stem diameter (mm), percentage of protein in the fruits and soil pH. The results obtained from the experiment can be summed up above the treatment of air conditioning at saline level 6 ds m-1 in branch per plant with 12.3 and the most significant results obtained from the experiment can be summed up above the treatment of air conditioning at saline level 4 ds m-1 in stem diameter 2.03 mm. The results showed a decrease in branch per plant and stem diameter (mm) by increasing the salinity of irrigation water by 8 ds m-1 and the increase in the addition of humic acid and potassium fertiliser. The results showed a decrease in soil acidity (pH) increasing the salinity of irrigation and increasing fruit protein content by increasing the salinity.

Relief effect of biochar on continuous cropping of tobacco through the reduction of p-hydroxybenzoic acid in soil

Biochar application to soil has proven to be an excellent approach for decreasing the concentration of auto-toxic compounds and promoting plant growth in continuous-cropping fields. However, the mechanisms underlying the action pathway among biochars, auto-toxic compounds and tobacco remain unknown. In this study, we conducted an experiment tracking the incidence rate of black rot and auto-toxic compounds for a 3-year continuous-cropping tobacco pot trial in response to biochar treatment intensity compared with that of non-biochar treatment. Biochar inhibited the incidence of black rot. Using ultra-high-performance liquid chromatography–mass spectrometry (UPLC‒MS/MS), we revealed that biochar can effectively decrease the concentration of p-hydroxybenzoic acid (PHA), which is associated with the incidence rate of black rot (R2 = 0.890, p < 0.05). The sorption kinetics and isotherm of PHA sorption on biochar indicate that the coexistence of heterogeneous and monolayer sorption plays an important role in the adsorption process. Using Molecular dynamics (MD), Density functional theory (DFT) and Independent gradient model (IGM) analyses, we provide evidence that van der Waals force (vdW), π–π bonds and H-bonds between biochar and PHAs are the dominant factors that affect adsorption capacity. Moreover, the molecular adsorption rate (Nbiochar: NPHAs = 1:4) was theoretically calculated. In contrast, biochar dramatically increased nutrient retention capacity and improved soil properties, further enhancing tobacco quality, including its agronomic and physiological traits. Therefore, we considered that biochar not only relieved continuous cropping but also improved soil properties suitable for tobacco growth. Together, we demonstrate that the action of biochar in continuously cropped soil improves soil traits and alleviates auto-toxic compound toxicity. These data contribute to the direction of modified biochar application to improve continuous-cropping soil.

Nutrients Management and Till with Assorted Raised Seedbeds Affecting Pedocals Soil Traits

Nutrients Management and Till with Assorted Raised Seedbeds Affecting Pedocals Soil Traits

Film mulching counteracts the adverse effects of mild moisture deficiency, and improves the quality and yield of Cyperus esculentus. L grass and tuber in the oasis area of Tarim Basin.

Plastic film mulching (PFM) and deficit irrigation (DI) are vital water-saving approaches in arid agriculture. Cyperus esculentus is a significant crop in dry zones. However, scant data exists on the impacts of these water-saving methods on C. esculentus yield and quality. Using randomized block experiment design. Three irrigation strategies were tested: CK (standard irrigation), RW20 (20% water reduction), and RW40 (40% water reduction). Mulchin treatments included film mulching (FM) and no film mulching (NFM). Results revealed substantial effects of film mulching and drip irrigation on soil nutrients and physical properties, with minor influence on grass, root, and tuber stoichiometry. PF treatment, DI treatments, and their interaction significantly affected C. esculentus forage and tuber yields. Initially, grass and tuber yields increased and then decreased with reduced irrigation. The highest yields were under RW20 (3716.31 and 4758.19 kg/ha). FM increased grass and tuber yield by 17.99% and 8.46%, respectively, over NFM. The water reduction augmented the biomass distribuiton of the leaf and root, while reducing the tuber biomass in NFM. FM significantely impacted grass ether extract content, while reduced water influenced grass and tuber crude protein and tuber ether extract content. Mild water stress increased ether extract, crude protein, and soluble matter in grass and tubers, while excessive RW decreased them. Integrating soil traits, nutrients, yield, and quality, findings indicate C.esculentus yield and quality primarily hinge on soil water content, pond hydrogenase, and electrical conductivity. Based on this results, the recommended strategy is to reduce irrigation by 20% for cultivating C. esculentus in this area.

Influence of rice straw biochar addition on soil traits and nutrient uptake of Artichoke (Cynara cardunculus)grown in Mercury-contaminatedsoils

The present pot experiment was therefore conducted to investigate the effect of biochar application on the selected properties of mercury polluted soils and uptake of Artichoke (Cynara cardunculus) grown in polluted soils.Biochar obtained from rice straw was added at various rates (0, 5, 10 t/ha) on the soil artificially contaminated with mercury at a different concentration (0, 10, 20 ppm). The research indicated a significant (P &lt; 0.01) improvement in electrical conductivity, pH, available phosphorus, total nitrogen, exchangeable bases, cation exchange capacity and organic carbon owing to biochar addition.Additionally, uptake of potassium, phosphorus and nitrogen by Artichoke (Cynara cardunculus) was significantly enhanced by biochar application. A significant decrease in uptake of mercury owing to biochar application was also noticed in heavily mercury-contaminated soil (20 ppm). Hence, biochar application is mostvital to improve soil quality and fertility, improve nutrients uptake, amend Hg contaminated soil and decrease the quantity of carbon formedowing to the biomassburning.

Small Farm Holder Cropping Systems Influence Microbial Profiles in an Equatorial Rainforest Agroecosystem

The metabarcoding of prokaryotic and fungal (Ascomycota only) ribosomal DNA was used to describe the microbial communities in soils of a remnant equatorial rainforest, maize–bean intercrop, and sugarcane in western Kenya. Cropping systems influenced the microbial community composition and functional traits (energy source and nutrient cycling) of bulk soil in each crop. Microbial richness and diversity tended to increase with cultivation intensity. The soil of the maize–bean intercrop had lower percentages and sugarcane had higher percentages of unique amplicon sequence variants of both bacteria and fungi compared to the remnant forest. Functional traits were altered by cultivation intensity. Compared to remnant forest soils, maize–bean intercrop soil had lower percentages of aerobic chemoheterotrophic bacteria and higher percentages of N-cycling bacteria, while sugarcane had higher percentages of aerobic chemoheterotrophic bacteria and lower percentages of N-cycling bacteria. In the face of increasing forest loss and pressures for agricultural productivity, this landscape provides a rich site for studying the impacts of cropping systems on soil health.

Bayesian Inference of Soil Traits from Green Manure Fields in a Tropical Sandy Soil

Bayesian Inference of Soil Traits from Green Manure Fields in a Tropical Sandy Soil

How revegetation reinforces soil at early stage of restoration: A 6‐year field study in southwest China

AbstractBackground and aimsRestoring vegetation on hillslopes has been found to increase soil strength, thereby reducing the risk of soil erosion and shallow landslides. However, limited information is available on the temporal changes in root biomechanical traits and increased soil shear strength related to vegetation growth following restoration with different species.MethodsIn 2012, Symplocos setchuensis, Buxus megistophylla, and Cynodon dactylon were replanted in a forest gap in Jinyun Mountain, Beibei District, China, and studied over a 6‐year period. We measured root traits (root tensile strength, Young's modulus, cellulose content, and root density) and soil traits (cohesion and internal friction angle) at two soil depths (0–20 and 20–40 cm) for undisturbed and reconstituted samples.ResultsS. setchuensis was found to have the highest tensile strength and resistance to failure for root diameters &lt;2 mm. With elapsed time, tensile strength and cellulose content decreased. Cohesion and root mechanical reinforcement of topsoil generally increased with time (+10% per year). Root chemical and mechanical effects contributed approximately 50% to soil reinforcement. C. dactylon had the fastest growth rate and reinforced the topsoil soil rapidly, whereas S. setchuensis exhibited a consistent increase in soil reinforcement during the study period and provided more deep roots that could reinforce subsoil.ConclusionChemical and mechanical effects almost equally contributed to soil reinforcement. Although the relative contributions varied for different species, the variation in each contribution sheds new light on the sustainable use of vegetation for mitigating shallow landslides in mountainous areas.

The Impact of Vegetation Types on Soil Hydrological and Mechanical Properties in the Hilly Regions of Southern China: A Comparative Analysis

Background: Vegetation roots are considered to play an effective role in controlling soil erosion by benefiting soil hydrology and mechanical properties. However, the correlation between soil hydrology and the mechanical features associated with the variation root system under different vegetation types remains poorly understood. Methods: We conducted dye-tracer infiltration to classify water flow behavior and indoor experiments (including tests on soil bulk density, soil organic carbon, mean weight diameter, soil cohesion, root density, etc.) to interpret variation patterns in three forest systems (coniferous and broad-leaved mixed forest, CBF; coniferous forest, CF; Phyllostachys edulis, PF) and fallow land (FL). Results: Based on the soil dye-tracer infiltration results, the largest dyeing area was observed in CF (36.96%), but CF also had the lowest infiltration rate (60.3 mm·min−1). The soil under CBF had the highest shear strength, approximately 25% higher than other vegetation types. CF exhibited the highest aggregate stability, surpassing CBF by 98.55%, PF by 34.31%, and FL by 407.41%, respectively. Additionally, PF forests showed the greatest root biomass and length. The results of correlation analysis and PCA reveal complex relationships among hydrological and mechanical soil traits. Specifically, soil cohesion does not exhibit significant correlations with hydrological traits such as the dyeing area, while traits like MWD and PAD show either positive or negative associations with hydrological traits. Root traits generally exhibit positive relationships with soil mechanical traits, with limited significant correlations observed with hydrological traits. Conversely, we found that root biomass contributes significantly to the dyeing area (accounting for 51.48%). Conclusions: Our findings indicate that the reforestation system is a successful approach for conserving water and reducing erosion by increasing soil-aggregated stability and shear strength, causing water redistribution to be more homogenized across the whole soil profile.

Effects of farmland residual mulch film-derived microplastics on the structure and function of soil and earthworm Metaphire guillelmi gut microbiota

Microplastics derived from polyethylene (PE) mulch films are widely found in farmland soils and present considerable potential threats to agricultural soil ecosystems. However, the influence of microplastics derived from PE mulch films, especially those derived from farmland residual PE mulch films, on soil ecosystems remains unclear. In this study, we analyzed the bacterial communities attached to farmland residual transparent PE mulch film (FRMF) collected from peanut fields and the different ecological effects of unused PE mulch film-derived microplastics (MPs) and FRMF-derived microplastics (MPs-aged) on the soil and earthworm Metaphire guillelmi gut microbiota, functional traits, and co-occurrence patterns. The results showed that the assembly and functional patterns of the bacterial communities attached to the FRMF were clearly distinct from those in the surrounding farmland soil, and the FRMF enriched some potential plastic-degrading and pathogenic bacteria, such as Nocardioidaceae, Clostridiaceae, Micrococcaceae, and Mycobacteriaceae. MPs substantially influenced the assembly and functional traits of soil bacterial communities; however, they only significantly changed the functional traits of earthworm gut bacterial communities. MPs-aged considerably affected the assembly and functional traits of both soil and earthworm gut bacterial communities. Notably, MPs had a more remarkable effect on nitrogen-related functions than the MPs-aged in numbers for both soil and earthworm gut samples. Co-occurrence network analysis revealed that both MPs and MPs-aged enhanced the synergistic interactions among operational taxonomic units (OTUs) of the composition networks for all samples. For community functional networks, MPs and MPs-aged enhanced the antagonistic interactions for soil samples; however, they exhibited contrasting effects for earthworm gut samples, as MPs enhanced the synergistic interactions among the functional contents. These findings broaden and deepen our understanding of the effects of FRMF-derived microplastics on soil ecosystems, suggesting that the harmful effects of aged plastics on the ecological environment should be considered.

Soil compaction development facilitated the decadal improvement of the root system architecture and rhizosheath soil traits of soybean in the North China Plain

Machinery agriculture has increased crop yield but induced soil compaction worldwide in the last decades. The crop yield increase is partly attributed to high-yielding crop breeding, but the effects of emerging soil compaction on the selection of root system traits and its impact on yield increase remain unclear. The objectives of this study were 1) to identify the effects of soil compaction on grain yield and root system architecture and rhizosheath soil traits of soybean (Glycine max (L.) Merr.) at the full-bloom stage, 2) to understand whether and how the development of soil compaction affected the selection of merit root and rhizosheath soil traits through crop breeding and contributed to soybean grain yield increase. Thirty-four most popular soybean cultivars released before and after the wide use of agricultural machinery in the North China Plain were grown in the fields without (NOM) and with (COM) applied soil compaction in 2017 and 2018. The phenotypes of root system, including rhizosheath soil, of soybean, were separated by soil compaction and cultivar release period, confirming the development of soil compaction and its impacts on the co-development of rhizosheaths with the root system of soybean. The correlation with the year of release of the cultivar demonstrated that 21 out of the 24 measured traits were selected by crop breeding. Multivariate analysis of the variance demonstrated that the selection of thinner hypocotyl, more root tips, and denser rhizosheath soil were relevant to the soil compaction development. The selection of shorter plant height, larger root biomass and area, thinner root tip, thicker taproot, and rhizosheath soil mass were likely relevant to the experimental year factor caused by drought or its associated change in nutrient availability. Most of the selected traits increased the resistance or the resilience to soil compaction and nine of them correlated with the grain yield of cultivars released at different periods. These results for the first time suggested that crop breeding increased grain yield partly by increasing the resistance and resilience to soil compaction. Soil compaction could be considered in a future breeding program design to increase crop breeding efficiency by selecting resistant and resilient root traits.

Morpho-Ecological Study of Wild Onobrychis altissima Grossh. and Onobrychis cyri Grossh. (Onobrychis MILL.) in Azerbaijan

Abstract Knowing the distribution and eco-geography of native Onobrychis altissima and O. cyri in Azerbaijan is critical for the implementation of strategies for their conservation and sustainable use. This study includes 27 specimens from nine wild populations of O. altissima and O. cyri collected from their natural habitats in Azerbaijan. The aims of this study are to provide a detailed morphological and eco-geographic characterization of O. altissima and O. cyri, to determine the distribution and environmental variables that define the eco-geographic zones native to Azerbaijan, and also to determine the priority areas for in situ conservation of native Onobrychis germplasm in Azerbaijan. Besides, research work was carried out for the purpose of clarifying the distribution areas, discovering more resistant species for selection, as well as enriching the genetic resources and Her-barium Fund. The specimens were biometrically assessed using 34 quantitative and 10 qualitative morphological characters. At each site, we recorded eco-geographic data regarding longitude, latitude, altitude, slope inclination, slope orientation, maximum and minimum temperatures, annual precipitation, relief, as well as soil traits including texture, humus, organic carbon, total nitrogen, pH, phosphorus pentoxide, potassium oxide, and magnesium. Cluster analysis of morphological characters showed that the nine populations could be divided into three main groups. Furthermore, principal component analysis (PCA) of eco-geographic data is discussed. The article presents tables and phenograms reflecting some eco-geographic information and a distribution map of the species.