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Soil acts as a crucial reservoir for both nutrients and microorganisms, hosting a wide range of microbial communities essential for ecosystem health. Particularly noteworthy are the interactions between plants and these microbes in the rhizosphere, as they actively contribute to sustaining plant well-being and fortifying plants against environmental pressures. Challenges, such as drought and salinity, pose significant threats to agricultural output and overall plant development. Therefore, it is imperative to explore the intricate mechanisms of stress responses to develop strategies to bolster plant resilience. Plant growth-promoting rhizobacteria (PGPR) offer a promising avenue for alleviating stress-induced damage in plants. Recent progress in the understanding of drought stress has shed light on the physiological and biochemical reactions within plants, emphasizing the critical role of abscisic acid (ABA) in stress mitigation. Similarly, advancements in research on salinity tolerance have elucidated the functions of ion transporters and stress signaling proteins. PGPRs play a crucial role in enhancing plant stress resilience through various mechanisms, including the regulation of ethylene levels, enhancement of nutrient absorption, and synthesis of hormones and enzymes. Utilizing the synergistic potential of plant-microbial interactions presents a promising strategy for tackling salinity and drought challenges in agriculture. Furthermore, PGPRs are instrumental in mitigating the effects of organic pollutants and heavy metals via mechanisms such as ACC deaminase activity. Innovative approaches, such as constructed wetland systems, leverage plant-microbial interactions to enhance water quality by purging pollutants. [ABSTRACT FROM AUTHOR]

[Objectives] The paper aimed to study the effects of four kinds of different plant growth-promoting rhizobacteria(PGPR)on the rhizosphere environment change, growth and physiology of Isatis indigotica, in order to provide theoretical reference for the production of I. indigotica. [Methods] The four kinds of PGPR, which were named Enterobacter sp. GS-22, Bacillus sp. GS-27, Sphingobacterium sp. GS-72 and Acinetobacter sp. GS-103, were applied in pot experiment. In order to evaluate the growth promotion effect of PGPR on I. indigotica, the relevant indicators were determined, including soil physical and chemical properties, growth traits, photosynthetic parameters, nutrient and related enzyme activities, active components, and so on. [Results] The four kinds of PGPR had different effects on soil physicochemical properties. GS-22 and GS-72 could increase soil total nitrogen content, GS-22 and GS-103 significantly increased soil available phosphorus content, and soil organic matter content in all treatment groups significantly increased. Compared with not inoculated with soil rhizosphere bacteria(CK), the activities of soil urease, soil alkaline phosphatase and soil sucrase increased by 33. 78%-73. 70%, 49. 51%-83. 93% and 8. 10%-186. 26%, respectively. Four rhizosphere bacteria promoted the growth of I. indigotica, and increased plant height, taproot diameter, dry weight, fresh weight, and so on, and GS-22 had the most significant effect on the growth traits of I. indigotica. PGPR also had significant effects on physiology of I. indigotica. The activities of nitrate reductase, sucrose synthetase and acid phosphatase increased by 53. 81%-125. 19%, 57. 64%-76. 54% and 7. 87%-22. 78% compared with CK, respectively. Four rhizosphere bacteria were beneficial to the accumulation of nutrients, like soluble sugars, free amino acids, and active components, like total flavonoids, indigo and indirubin of I. indigotica, in which GS-22 and GS-27 especially increased the contents of total flavonoids, indigo and indirubin. [Conclusions] The rhizosphere bacteria GS-22, GS-27, GS-72 and GS-103 had the ability to promote plant growth in I. indigotica, improve the soil environment, and promote the growth and physiological processes of I. indigotica. Among them, GS-27 had the best comprehensive capability. The screened strains provided strategies for developing specialized microbial fertilizer for I. indigotica and achieving increased yield and efficiency of Chinese herbs. [ABSTRACT FROM AUTHOR]

To investigate the effects of Pseudomonas monteilii SX001 on various parameters of cucumber plants under salt stress, the salt-sensitive cucumber variety "Jinyou No. 4" was used as the test material, and coconut bran was used to simulate salt stress by applying NaCl solution. The results indicated that salt stress significantly reduced the morphological structure, relative growth rate, root morphology, and photosynthetic parameters of the cucumber plants. Leaf starch, soluble sugar, and sucrose contents significantly increased, whereas their levels in roots decreased. Cell membrane damage leads to the accumulation of reactive oxygen species and malondialdehyde, with notable increases in the activities of major antioxidant enzymes such as SOD, CAT, and POD. Nitrogen metabolism was disrupted, as evidenced by a significant decrease in nitrate nitrogen content and an increase in ammonium nitrogen content, as well as a significant reduction in the activity of NR enzymes involved in nitrogen metabolism. The enzyme activity in the cucumber rhizosphere soil decreased. However, Pseudomonas monteilii SX001 significantly enhanced the growth of cucumber seedlings under salt stress, improved photosynthetic efficiency, and facilitated sugar transformation and transport via glucose metabolism. Additionally, Pseudomonas monteilii SX001 reduced the reactive oxygen content and increased antioxidant enzyme activity. It also increased the activity of substrate enzymes and decreased the diversity of rhizosphere soil microorganisms but also increased the abundance of Asticcacaulis, Acinetobacter, Brevundimonas, Pseudomonas, and Enterobacter. These findings demonstrate that Pseudomonas monteilii SX001 is a promising bioinoculant for alleviating salt stress in cucumber production and improving soil health. [ABSTRACT FROM AUTHOR]

ABSTRACT The rhizosphere soil properties and microbial communities of Lilium tsingtauense, an endangered wild plant, have not been examined in previous studies. Here, we characterized spatial variation in soil properties and microbial communities in the rhizosphere of L. tsingtauense. We measured the abundance of L. tsingtauense at different altitudes and collected rhizosphere and bulk soils at three representative altitudes. The results showed that L. tsingtauense was more abundant, and the rhizosphere soil was richer in nitrogen, phosphorus, potassium, water content, and organic matter and more acidic at high altitudes than at lower altitudes. The diversity and richness of rhizosphere bacteria and fungi increased with altitude and were higher in rhizosphere soil than in bulk soil. In addition, ectomycorrhizal fungi, endophytic fungi, and nitrogen-fixing bacteria were more abundant, and plant-pathogenic fungi were less abundant at high altitudes. Co-occurrence network analysis identified four key phyla (Bacteroidota, Proteobacteria, Ascomycota, and Basidiomycota) in the microbial communities. We identified a series of microbial taxa (Acidobacteriales, Xanthobacteraceae, and Chaetomiaceae) and rhizosphere soil metabolites (phosphatidylcholine and phosphatidylserine) that are crucial for the survival of L. tsingtauense. Correlation analysis and random forest analysis showed that some environmental factors were closely related to the rhizosphere soil microbial community and played an important role in predicting the distribution and growth status of L. tsingtauense. In sum, the results of this study revealed altitudinal variation in the rhizosphere microbial communities of L. tsingtauense and the factors driving this variation. Our findings also have implications for habitat restoration and the conservation of this species.IMPORTANCEOur study highlighted the importance of the rhizosphere microbial community of the endangered plant L. tsingtauense. We found that soil pH plays an important role in the survival of L. tsingtauense. Our results demonstrated that a series of microbial taxa (Acidobacteriales, Xanthobacteraceae, Aspergillaceae, and Chaetomiaceae) and soil metabolites (phosphatidylcholine and phosphatidylserine) could be essential indicators for L. tsingtauense habitat. We also found that some environmental factors play an important role in shaping rhizosphere microbial community structure. Collectively, these results provided new insights into the altitudinal distribution of L. tsingtauense and highlight the importance of microbial communities in their growth.

Salt stress as one of the common abiotic stresses can affect plant growth and development. Root exudates are considered as an important medium for“information”exchange between plants and rhizosphere environment. When plants sufferred in salt stress, the composition and content of root exudates would change to affect the growth and development of plants. This article summarizes the components, detection methods, mechanism of action and changing trends. Root exudates mainly contained amino acids, sugars, organic acids and phenolic acids, etc. The high performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), liquid chromatographymass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) are widely used to identify and detect compositions and contents of root exudates. Combined with previous studies, the changes of composition and content of amino acids, sugars, organic acids, etc. under salt stress were summarized. From the aspect of physical and chemical environment and rhizosphere microorganisms, the putative roles of root exudates under salt stress were also summarized, including: 1) acting as signal molecules in plant suffering to salt tolerance; 2) maintaining the homeostasis of root cells; and 3)affecting rhizosphere environment. The change mechanism of amino acids and sugars in salt tolerance of [ABSTRACT FROM AUTHOR]

Excessive Cd in rice grains produced with acidic paddy soil is receiving increasingly widespread attention because it endangers human health. Applying organic materials (OM) and lime (L) is a common technique used to reduce Cd concentration in grains (CdG). Nevertheless, the mechanism by which their simultaneous application affects the Cd phytoavailability in soilrice systems remains ambiguous. In the current study, we adopted a rhizobag pot culture test to explore the influences of single application of OM [rice straw (RS), milk vetch (MV)], L, and their co-utilization on Cd phytoavailability and the associated mechanisms. The results showed that the application of RS, MV, L, L + RS (LRS), and L + MV (LMV) significantly decreased CdG by 26.9%, 38.2%, 48.6%, 50.0%, and 53.0%, respectively. Fe plaque (IP) formation was not affected by these treatments; however, Cd sequestration in IP (CdIP) was significantly reduced. CdIP was significantly reduced by 18.3%, 23.6%, 43.8%, 33.1%, and 41.4%, after RS, MV, L, LRS, and LMV treatments, respectively. Additionally, available Cd concentrations in rhizospheric soil (RHS) were significantly reduced by 11.5%, 14.8%, 15.1%, and 18.4%, after MV, L, LRS, and LMV treatments, respectively. Cd availability in RHS was significantly influenced by pH, dissolved organic carbon concentration, and Zn, Fe, and Mn availability. The results of the structure equation mode showed that CdG was mainly affected by CdIP, followed by Cd availability and the pH of RHS. In conclusion, the reduction of CdG by OM, L, and their co-utilization was the results of their combined effects of reducing Cd availability in RHS, CdIP, and Cd uptake by the roots. This study emphasizes that the reduction of CdG is a result of the dual effects of reducing Cd availability in RHS and CdIP after amendments application. L application alone or in conjunction with OM is an efficient practice to reduce CdG in acidic Cd-contaminated paddy fields.

The frequency and intensity of droughts have increased in recent decades, and climate change is a major driver of global droughts. Among abiotic stress factors, drought is one of the major threats to agricultural production. In order to further understand the response mechanism of plants to drought stress and the adaption ability of plants to drought stress, this studyretrospectively reviews the plant morphological structure and ultrastructure, photosynthesis, stomatal regulation mechanism, reactive oxygen species metabolism and plant antioxidant protection mechanism, plant osmotic regulation mechanism, plant endogenous hormone regulation mechanism, xylem hydraulic characteristics, carbon-nitrogen metabolism and its source-sink relationship, autophagy defense mechanism and molecular response mechanism against drought stress. Meanwhile, we believe that plant responses to drought stress should also involve the soil and rhizosphere environment. Therefore, the stability of soil aggregates, rhizosphere soil nutrients, plant root exudates, rhizosphere soil enzyme activity, rhizosphere soil microorganisms, soil respiration, soil carbon and nitrogen emissions under drought stress are also reviewed. Finally, this study summarizes the response network of the plant-soil-rhizosphere environment to drought stress, discusses regulatory measures to alleviate the adverse effects of drought stress and proposes future research directions. [ABSTRACT FROM AUTHOR]

This basic reviewed that phytoremediation as the most common and economical method, has been widely used in the remediation process of heavy metal pollution in mining soils・ In the process of plant remediation of heavy metal contaminated soil, heavy metal transport and migration directly affect the remediation effect of plants・ Therefore, it is very important to clarify the influencing factors of heavy metal transport and migration in mining soil. Through further analysis of the factors affecting the transfer and transformation of heavy metals in the mining soil, it is found that the transfer and migration of heavy metals in the mining soil is not only affected by soil clay minerals, chemical chelators and other chemical processes, but also greatly affected by rhizosphere environment. It is concluded that both the physical and chemical properties of soil and the influence of rhizosphere environment should be taken into account in the process of phytoremediation of contaminated soil in mining areas. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Perennial grains provide various ecosystem services compared to the annual counterparts thanks to their extensive root system and permanent soil cover. However, little is known about the evolution and diversification of perennial grains rhizosphere and its ecological functions over time. In this study, a suite of -OMICSs - metagenomics, enzymomics, metabolomics and lipidomics - was used to compare the rhizosphere environment of four perennial wheat lines at the first and fourth year of growth in comparison with an annual durum wheat cultivar and the parental species Thinopyrum intermedium. We hypothesized that wheat perenniality has a greater role in shaping the rhizobiome composition, biomass, diversity, and activity than plant genotypes because perenniality affects the quality and quantity of C input - mainly root exudates - hence modulating the plantmicrobes crosstalk. In support of this hypothesis, the continuous supply of sugars in the rhizosphere along the years created a favorable environment for microbial growth which is reflected in a higher microbial biomass and enzymatic activity. Moreover, modification in the rhizosphere metabolome and lipidome over the years led to changes in the microbial community composition favoring the coexistence of more diverse microbial taxa, increasing plant tolerance to biotic and abiotic stresses. Despite the dominance of the perenniality effect, our data underlined that the OK72 line rhizobiome distinguished from the others by the increase in abundance of Pseudomonas spp., most of which are known as potential beneficial microorganisms, identifying this line as a suitable candidate for the study and selection of new perennial wheat lines. [ABSTRACT FROM AUTHOR]

Perennial grains provide various ecosystem services compared to the annual counterparts thanks to their extensive root system and permanent soil cover. However, little is known about the evolution and diversification of perennial grains rhizosphere and its ecological functions over time. In this study, a suite of -OMICSs - metagenomics, enzymomics, metabolomics and lipidomics - was used to compare the rhizosphere environment of four perennial wheat lines at the first and fourth year of growth in comparison with an annual durum wheat cultivar and the parental species Thinopyrum intermedium. We hypothesized that wheat perenniality has a greater role in shaping the rhizobiome composition, biomass, diversity, and activity than plant genotypes because perenniality affects the quality and quantity of C input – mainly root exudates – hence modulating the plant-microbes crosstalk. In support of this hypothesis, the continuous supply of sugars in the rhizosphere along the years created a favorable environment for microbial growth which is reflected in a higher microbial biomass and enzymatic activity. Moreover, modification in the rhizosphere metabolome and lipidome over the years led to changes in the microbial community composition favoring the coexistence of more diverse microbial taxa, increasing plant tolerance to biotic and abiotic stresses. Despite the dominance of the perenniality effect, our data underlined that the OK72 line rhizobiome distinguished from the others by the increase in abundance of Pseudomonas spp., most of which are known as potential beneficial microorganisms, identifying this line as a suitable candidate for the study and selection of new perennial wheat lines.

Determining the nutrient requirements of industrial hemp to increase the yield requires quantifying variations in soil nutrients and enzyme activities in different growth stages, along with relevant soil microbial response. This study investigated the effects of different growth stages of industrial hemp on rhizosphere soil nutrients, enzyme activities, and microbial communities. The results showed that with the increase in the growth stages, the pH and available phosphorus (AP) decreased, while the soil organic matter (SOM), available nitrogen (AN), and available potassium (AK) increased substantially, indicating that the demand for nutrients of industrial hemp was constantly changing. Proteobacteria, Acidobacteria, Ascomycota, and Basidiomycota were found to be the keystone taxa to adapt to the nutrient requirements of industrial hemp at different growth stages by regulating soil enzyme activity. Furthermore, using the redundancy analysis and Spearman's correlation analysis, we found that microbial taxonomic composition was related to the variations in AN, AP, and pH. In general, we emphasized that the interaction between industrial hemp and soil is closely related to the growth stage, which increases plant adaptability and growth because of the change of soil microorganisms. [ABSTRACT FROM AUTHOR]

Strengthening rhizosphere effects to enhance pollutant removal is a hotspot of constructed wetlands (CWs) research in recent years, and improving the root traits and metabolic capacity of macrophytes is crucial for strengthening rhizosphere effects. In the field experiment, two types of subsurface flow (SSF) CWs (CW10 and CW20, with substrate depths of 10 and 20 cm, respectively) under the vertical spatial stress of roots (VSSR) and two types of non-VSSR SSF CWs (CW40 and CW60) were adopted with Typha orientalis as cultivated plants to investigate the variability of root development, metabolism, and pollutant removal at different substrate depths. VSSR induced substantial redundant root development, which significantly increased root-shoot ratio, fine and lateral root biomass, root porosity, and root activity, with lateral and fine root biomass of CW20 reaching 409.17 and 237.42 g/m2, respectively, which were 3.18 and 5.28 times those of CW60. The radical oxygen loss (ROL) and dissolved organic carbon (DOC) levels of CW20 single plant were 1.36 and 4.57 times higher than those of CW60, respectively, and more types of root exudates were determined (e.g., aldehydes, ketones and amides). More aerobic heterotrophs (e.g., Massilia , Planomicrobium), nitrification bacteria (e.g., Ellin6067 , Nitrospira), aerobic denitrification bacteria (e.g., Bacillu , Chryseobacterium , Pseudomonas) and denitrification phosphorus accumulating organisms (e.g., Flavobacterium) were enriched in the rhizosphere of CW20. This changed the main transformation pathways of pollutants and enhanced the removal of pollutants, with the COD, TN and TP average removal rates of CW20 increasing by 9.99%, 13.28% and 8.92%, respectively, compared with CW60. The ideotype root system architecture CW (RSACW; CW20) constructed in this study, which consists of a large number of fine and lateral roots, can stimulate more efficient rhizosphere effects stably and continuously. [Display omitted] • A novel SSF CW with ideotype root system architecture (RSACW, CW20) was proposed. • RSACW had 3.18 and 5.28 times more lateral and fine roots than CW60. • Dissolved organic carbon in CW20 was 4.57 times higher than in CW60. • RSACW enhanced the aerobic transformation pathways of pollutants. [ABSTRACT FROM AUTHOR]

In the acid paddy soil in Xiangtan, Hunan Province, rhizosphere chamber culture experiments were conducted to explore the remediation effects of sepiolite on cadmium (Cd) -contaminated soil using different depth treatments of the cultivated soil. The aim was to investigate the effects of sepiolite application depth on Cd bioavailability in soil, plant Cd absorption, and rhizosphere environment. The results showed that, compared with the control without sepiolite, the pH value of rhizosphere and non-rhizosphere soil increased by 1.00~ 1.16 and 0.59~1.21 units using treatments at depths of 20, 10, and 5 cm; further, the available Cd content in the rhizosphere and five nonrhizosphere soil layers decreased by 0.02%~3.40% and 1.00%~7.80%, respectively. In addition, when the sepiolite application depth was 5 cm (T2), the available Cd content of the rhizosphere and non-rhizosphere soil showed the largest decreases of 3.40% and 7.80%, respectively. Moreover, the Cd content of each part of the rice decreased after sepiolite treatments were applied at different depths, and the Cd content of each part of the rice had the biggest drop when the sepiolite was applied to the soil at a depth of 5 cm, preventing the root from reaching the unpassivated soil (T4) . Furthermore, compared to the control, the Cd content of the root decreased significantly (P<0.05) . At the same time, the plant height and yield of rice increased with treatments at different depths; the biggest rise was with treatments of T2 and T4, with significant differences (P<0.05) . Overall, it could be seen that the application of sepiolite in shallow tillage (a treatment applied under the 5 cm plow layer) resulted in the best effect in reducing soil Cd bioavailability, and it also reduced the Cd content in rice and significantly increased rice yield. [ABSTRACT FROM AUTHOR]

Agricultural production uses different types of fertilisation treatments, typically employing the combined application of organic fertiliser (OF) or organic–inorganic fertiliser (OIF) to improve soil quality. When coupled with cadmium (Cd), microplastics (MPs) affect plant growth and Cd accumulation in soils treated with different fertilisers. This study systematically examined the effects of polyurethane (PU) MPs coupled with Cd on the growth characteristics, root metabolite characteristics, rhizosphere bacterial community structure, and Cd bioavailability of maize under different long-term fertilisation treatments and soil types (red/cinnamon soil). The combined effects of PU MPs and Cd on maize growth differed across fertilisation treatments. Under OF, maize plants accumulated more Cd than under OIF. The accumulation of Cd in maize plants in red soil was twice that in cinnamon soil. Under OF, PU MPs promoted Cd activation by decreasing the soil pH, while root metabolites promoted Cd adsorption sites by synthesising specific amino acids, degrading aromatic compounds, and synthesising pantothenic acid and coenzyme A. Under OF, PU MPs can lower the soil pH to promote the activation of cadmium, while root metabolites promote root growth and increase cadmium adsorption sites by synthesizing specific amino acids, degrading aromatic compounds, and synthesizing pantothenic acid and coenzyme A, hereby promoting root Cd absorption. Under OIF, PU MPs act by influencing the biosynthesis of amino acids in root metabolites, enriching energy metabolism pathways, promoting the transport and translocation of mineral nutrients, thereby amplifying the "toxic effects" of Cd. This study provides new insights into the risk assessment of PU MPs and Cd coupling under different fertilisation treatments, and suggests that the prevention and control of combined PU MPs and Cd pollution in red soil under OF treatment should receive more attention in the future. [Display omitted] • PU and Cd combination effects on maize growth differ with fertilisation histories. • Cd accumulation is higher in plants with OF treatment than OIF treatment. • The activation and root metabolite pathway OF Cd under OF treatment are the key. • The root metabolite pathway under OIF treatment is the key. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Bio-organic fertilizer (BOF) had the better effect than organic fertilizer (OF) in grapevine. • BOF increased the soil fertility and improved the diversity and richness of soil microbial community. • BOF promoted the growth of root and seedling of grapevine. Grapevine seedlings need to absorb a lot of nutrients from the soil during the growth process, and appropriate fertilizer can greatly promote the growth of seedlings. The purpose of this study was to investigate the effects of different bio-organic fertilizers (BOF) on shoot and root growth, soil biochemical characteristics, and bacterial communities of 'Shine Muscat' and 'Kyoho' seedlings. Four treatments were established: no fertilizer (CK), chemical fertilizer + organic fertilizer (T1), chemical fertilizer + bio-organic fertilizer 1 (T2, containing Bacillus amyloliquefaciens), chemical fertilizer + bio-organic fertilizer 2 (T3, containing Trichoderma). The results showed that BOF had better effects on growth and rhizosphere environment of grapevine seedling than organic fertilizer (OF) treated group. The shoot growth, chlorophyll content, and root growth with BOF of grapevine seedlings were generally better than those treated with OF. Compared with T1, T2 and T3 made grapevine seedlings meet the fixed drying requirement (main shoot 0.8 m) 1–4 weeks earlier. The expansion of roots and the improvement of root activity under BOF treatment were also beneficial to plant growth. Moreover, transcriptome analysis showed that BOF enhanced the phytohormones and cell wall processes in grapevine root, and up-regulated the expression of cell wall-related genes such as XTH23, EXPs, PME17 , and auxin related genes such as ABCBs and GH3. In addition, BOF increased soil organic matter content, available nitrogen, available potassium, available phosphorus, and enzyme activity (soil catalase, urease, sucrase, and nitrate reductase). The Shannon and Chao values of T2 were higher than those of T1 and CK, which improved the diversity and richness of soil microbial community. As compared to CK, T2 treatment increased the symbiotic nitrogen fixing Proteobacteria by 4.10 %, and reduced Acidobacteria by 9.79 %. Actinobacteria, which is related to the degradation of stubborn polymers, was the dominant group in T2 treatment, accounting for 10.17 %. As compared to CK and T1, Actinobacteria was increased by 6.89 % and 5.66 %. In summary, BOF could promote the growth of grapevine seedlings by improving phenotypic traits, soil fertility, bacterial diversity, richness abundance, and provide theoretical and technical support for grapevine garden construction and tree management. [Display omitted] [ABSTRACT FROM AUTHOR]

Excessive Cd in rice grains produced with acidic paddy soil is receiving increasingly widespread attention because it endangers human health. Applying organic materials (OM) and lime (L) is a common technique used to reduce Cd concentration in grains (Cd G). Nevertheless, the mechanism by which their simultaneous application affects the Cd phytoavailability in soil rice systems remains ambiguous. In the current study, we adopted a rhizobag pot culture test to explore the influences of single application of OM [rice straw (RS), milk vetch (MV)], L, and their co-utilization on Cd phytoavailability and the associated mechanisms. The results showed that the application of RS, MV, L, L + RS (LRS), and L + MV (LMV) significantly decreased Cd G by 26.9%, 38.2%, 48.6%, 50.0%, and 53.0%, respectively. Fe plaque (IP) formation was not affected by these treatments; however, Cd sequestration in IP (Cd IP) was significantly reduced. Cd IP was significantly reduced by 18.3%, 23.6%, 43.8%, 33.1%, and 41.4%, after RS, MV, L, LRS, and LMV treatments, respectively. Additionally, available Cd concentrations in rhizospheric soil (RHS) were significantly reduced by 11.5%, 14.8%, 15.1%, and 18.4%, after MV, L, LRS, and LMV treatments, respectively. Cd availability in RHS was significantly influenced by pH, dissolved organic carbon concentration, and Zn, Fe, and Mn availability. The results of the structure equation mode showed that Cd G was mainly affected by Cd IP , followed by Cd availability and the pH of RHS. In conclusion, the reduction of Cd G by OM, L, and their co-utilization was the results of their combined effects of reducing Cd availability in RHS, Cd IP , and Cd uptake by the roots. This study emphasizes that the reduction of Cd G is a result of the dual effects of reducing Cd availability in RHS and Cd IP after amendments application. L application alone or in conjunction with OM is an efficient practice to reduce Cd G in acidic Cd-contaminated paddy fields. [Display omitted] • Organic matter and lime co-utilization decreased Cd in rice grains (Cd G). • Rhizosphere soil pH, DOC, and Zn, Fe, and Mn availability affect Cd availability. • Organic matter/lime co-utilization reduced Cd sequestration in Fe plaque (Cd IP). • Amendments reduced Cd uptake by roots. • Cd G was mainly affected by Cd IP , followed by Cd availability and soil pH. [ABSTRACT FROM AUTHOR]

The depth of the substrate of subsurface flow (SSF) constructed wetlands (CWs) is closely related to their cost and operation stability. To explore the physiological regulation mechanism of wetland plants and pollutant removal potential of SSF CWs under "vertical spatial stress of roots" (by greatly reducing the depth of the substrate in SSF CWs to limit the vertical growth space of roots, VSSR), the physiological response and wetland purification effect of a 0.1 m Canna indica L. CW under VSSR were studied compared with conventional SSF CWs (0.6 m, 1.2 m). The results demonstrated that VSSR significantly enhanced the dissolved oxygen (DO) concentration (p < 0.05) within the SSF CWs, with the DO in 0.1 m CW remaining stable at over 3 mg/L. Under the same hydraulic retention time (HRT), VSSR significantly improved the removal effect of pollutants (p < 0.05). The removal rates of COD, NH 4 +-N, and total phosphorus (TP) remained above 87%, and the mean removal rates of total nitrogen (TN) reached 91.71%. VSSR promoted the morphological adaptation mechanisms of plants, such as significantly increased root-shoot ratio (p < 0.05), changed biomass allocation. Plants could maintain the stability of the photosynthetic mechanism by changing the distribution of light energy. The results of microbial community function prediction demonstrated that aerobic denitrification was the main mechanism of N transformation in the 0.1 m CW under VSSR. VSSR could induce the high root activity of plants, augment the concentration of root exudates, enhance the redox environment of the plant rhizosphere, further foster the enrichment of aerobic denitrifying bacteria, and strengthen the absorption efficiency of wetland plants and substrate, thus achieving an efficient pollutant removal capacity. Studies showed that VSSR was an effective means to enhance the rhizosphere effect of plants and pollutant removal in SSF CWs. [Display omitted] • Plants change growth allocation strategy to adapt to VSSR in SSF CWs. • VSSR significantly improves oxygen enrichment environment of SSF CWs. • VSSR enables plants to make directional selection for rhizosphere microorganisms. • VSSR is an effective means to enhance plant rhizosphere effect in SSF CWs. [ABSTRACT FROM AUTHOR]

As an important parameter of forests growth, fine root lifespan plays an important role in plant water and nutrient absorption, and affects underground distribution of photosynthetic products and forest ecosystem carbon cycling. The impact of climate warming on fine root lifespan has become a hot issue under the context of global change. The responses of fine root lifespan to global warming will affect ecosystem carbon balance. We reviewed the research progress of the response characteristics and mechanism of fine root lifespan of trees to warming. Most stu-dies proposed that warming would affect fine root lifespan by changing rhizosphere soil environment, fine root morphology, and tree phenology. However, the growth and death of fine roots were affected by lots of factors, leading to differences in the research results on fine root lifespan due to natural environment of the study area, the way of warming, and the research objects. Therefore, it is of importance to comprehensively analyze the responses of fine root lifespan in forests under the background of climate warming to study the underground ecological process. In the future, the following research should be strengthened: 1) Combining multiple methods to warming underground and aboveground simutaneously, and explore more accurate and effective non-destructive observation methods. 2) Combining multiple observations to study the effects of warming on fine root lifespan. 3) Carrying out research on the effect of warming on fine root lifespan of different tree species, and deeply understand the response mechanism of fine root lifespan of different trees to warming. 4) A comprehensive analysis of the effects of warming on fine root lifespan from various perspectives, and an investigation into the mechanism of the combined effects of various factors on fine root lifespan. 5) The interaction between warming and other environmental factors fine root lifespan. 6) The effect of root architecture on the fine root lifespan after warming. 7) The effects of rhizosphere microorganisms (bacteria and fungi) on fine root lifespan after warming.

Four yellow pigmented strains (91A-561, 91A-576, 91A-593, and JM-1085) isolated from plant materials, showed 97.2-98.7 % 16S rRNA gene sequence similarities among each other and were studied in a polyphasic approach for their taxonomic allocation. Cells of all four isolates were rod-shaped and stained Gram-negative. Comparative 16S rRNA gene sequence analysis showed that the four bacteria had highest sequence similarities to Chryseobacterium formosense (97.2-98.7 %), Chryseobacterium gwangjuense (97.1-97.8 %), and Chryseobacterium defluvii (94.6-98.0 %). Sequence similarities to all other Chryseobacterium species were below 97.5 %. Fatty acid analysis of the four strains showed Chryseobacterium typical profiles consisting of major fatty acids C iso, C iso 2-OH/C ω7c, C iso ω9c, and C iso 3-OH, but showed also slight differences. DNA-DNA hybridizations with type strains of C. gwangjuense, C. formosense, and C. defluvii resulted in values below 70 %. Isolates 91A-561 and 91A-576 showed DNA-DNA hybridization values >80 % indicating that they belonged to the same species; but nucleic acid fingerprinting showed that the two isolates represent two different strains. DNA-DNA hybridization results and the differentiating biochemical and chemotaxonomic properties showed, that both strains 91A-561 and 91A-576 represent a novel species, for which the name Chryseobacterium geocarposphaerae sp. nov. (type strain 91A-561=LMG 27811=CCM 8488) is proposed. Strains 91A-593 and JM-1085 represent two additional new species for which we propose the names Chyrseobacterium zeae sp. nov. (type strain JM-1085=LMG 27809, =CCM 8491) and Chryseobacterium arachidis sp. nov. (type strain 91A-593=LMG 27813, =CCM 8489), respectively. [ABSTRACT FROM AUTHOR]

Multiple sugarcane ratooning cultivation is a common agricultural system in the south of China, and induces the decline of sugarcane productivity every year. This phenomenon may be caused by the alteration of rhizosphere soil microbial communities under different cropping pattern. In this study, T-RFLP was used to analyze the alteration of soil microbial communities in blank soil, new sugarcane planting soil and 1 year of sugarcane ratooning soil on which sugarcane cultivar Funong28 was planted. Based on experimental results, it was suggested that different cropping patterns had different effects on the structure of rhizosphere bacterial community. In first year of Funong28 ratooning soil, the diversity of microbial communities decreased, and some communities involved in basic metabolic processes and beneficial communities declined. It implied that sugarcane ratooning cultivation induced deterioration of soil ecological environment, minimizes the beneficial bacterial population and increases the availability of pathogens. Good farming patterns must be used to improve soil physical and chemical properties of soil, and promote development of beneficial bacterial communities in sugarcane ratooning cultivation. [ABSTRACT FROM AUTHOR]

The rhizosphere environment of tea ( Camellia sinensis Kuntze) intercropped with persimmon ( Diospyros kaki) differs from monocultures of tea. A trial was conducted to determine the effects of intercropping with persimmon on root exudates and soil nutrient condition of tea. Amino acid exuded in intercropping was three times higher than that in monoculture. Phenol, phenol/amino acid ration, dissolved sugar, and total organic acid were also lower in intercropping. The value of pH in soil was higher, and soil nutrient condition of rhizosphere, especially available nutrient, was not as well in intercropping as that in tea grown alone. While soil nutrient of non-rhizosphere was better than that in monoculture, tea quality and soil nutrient condition were better in intercropping ecosystem. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we evaluated if recA species-specific PCR assays could be successfully applied to identify environmental isolates of the widespread Burkholderia cepacia complex (Bcc) species. A total of 729 Bcc rhizosphere isolates collected in different samplings were assigned to the species B. cepacia genomovar I (61), B. cenocepacia recA lineage IIIB (514), B. ambifaria (124) and B. pyrrocinia (30), by means of recA (RFLP) analysis, and PCR tests were performed to assess sensitivity and specificity of recA species-specific primers pairs. B. cepacia genomovar I specific primers produced the expected amplicon with all isolates of the corresponding species (sensitivity, 100%), and cross-reacted with all B. pyrrocinia isolates. On the contrary, B. cenocepacia IIIB primers did not give the expected amplicon in 164 B. cenocepacia IIIB isolates (sensitivity, 68.1%), and isolates of distinct populations showed different sensitivity. B. ambifaria primers failed to amplify a recA-specific fragment only in a few isolates of this species (sensitivity, 93.5%). The absence of specific amplification in a high number of B. cenocepacia rhizosphere isolates indicates that recA specific PCR assays can lead to an underestimation of environmental microorganisms belonging to this bacterial species. [Copyright &y& Elsevier]

Land subsidence induced by underground coal mining leads to severe ecological and environmental problems. Arbuscular mycorrhizal fungi (AMF) have the potential to improve plant growth and soil properties. We aimed to assess the effects of AMF on the growth and soil properties of sea buckthorn under field conditions at different reclamation times. Inoculation with AMF significantly promoted the survival rate of sea buckthorn over a 50-month period, while also increasing plant height after 14, 26, and 50 months. Crown width after 14 months and ground diameter after 50 months of inoculation treatment were significantly higher than in the uninoculated treatment. AMF inoculation significantly improved plant mycorrhizal colonization rate and promoted an increase in mycelial density in the rhizosphere soil. The pH and electrical conductivity of rhizosphere soil also increased after inoculation. Moreover, after 26 and 50 months the soil organic matter in the inoculation treatment was significantly higher than in the control. The number of inoculated soil rhizosphere microorganisms, as well as acid phosphatase activity, also increased. AMF inoculation may play an active role in promoting plant growth and improving soil quality in the long term and is conducive to the rapid ecological restoration of damaged mining areas.