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1.
The species‐specific microbial root and rhizosphere colonization contributes essentially to the plant nutrient supply. The species number and colonization densities of cultivable saprotrophic microfungi and the activities of nutrient‐releasing soil enzymes (protease, acid and alkaline phosphatase, arylsulfatase) were investigated in the rhizosphere of one low mycorrhizal (Salix viminalis) and one higher mycorrhizal (S. × dasyclados) willow clone at a Eutric Cambisol in N Germany. After soil washing, in total 32 and 28 saprotrophic microfungal species were isolated and identified microscopically from the rhizosphere of S. viminalis and S. × dasyclados, respectively. The fungal species composition changed within the growing season but the species number was always lower under S. × dasyclados than under S. viminalis. Under both willow clones, the fungal colonization density was largest in spring, and the species number was largest in autumn. Acid‐phosphatase activity (p < 0.001) and protease activity (p < 0.003) were significantly affected by the Salix clone, whereas arylsulfatase and alkaline‐phosphatase activities did not show clone‐specific differences. All enzyme activities reached their maxima in the summer sampling. Rhizosphere colonization with Acremonium butyri, Cladosporium herbarum, and Penicillium janthinellum contributed significantly to explain the activities of acid phosphatase. Rhizosphere colonization with Cylindrocarpon destructans, Penicillium spinulosum, Plectosphaerella cucumerina, and Trichoderma polysporum contributed significantly to explain the arylsulfatase activities. Effects of the saprotrophic fungal colonization densities on the protease activities in the rhizosphere were low. Acid‐ and alkaline‐phosphatase and arylsulfatase activities in the rhizosphere soil were stronger affected by the composition of the saprotrophic fungal communities than by the Salix clone itself. In conclusion, the colonization density of some saprotrophic microfungi in the rhizosphere contributed to explain shifts in soil‐enzyme activities of the P and S cycles under different willow clones.  相似文献   

2.
Sulfonamide antibiotics reach soil via manure and adversely affect microbial diversity. Clear effects of these bacteriostatic, growth‐inhibiting antibiotics occur in the presence of a parallel input of microbial activity stimulating manure. Natural hot spots with already increased soil microbial activity are located in the rhizosphere, comprising microorganism such as Pseudomonas with plant growth promoting and pathogenic strains. The hypothesis was therefore that the antibiotic activity of sulfonamides is promoted in the rhizosphere even in the absence of manure, followed by shifts of the natural plant‐specific microbial community structure. This was evaluated by a laboratory experiment with Salix fragilis L. and Zea mays L. After 40 d of incubation, sub‐areas such as non‐rhizosphere soil, rhizosphere soil and plant roots were sampled. Effects on microbial community structure were analyzed using 16S rRNA gene fragment patterns of total bacteria community and Pseudomonas. Selected exoenzymes of N‐, P‐, and C‐cycling were used to test effects on microbial functions. Compared to the factors soil sub‐area and sulfadiazine (SDZ) content, plant species had the largest influence on the bacterial community structure and soil exoenzyme activity pattern. This was also reflected by an up to 1.5‐fold higher acid phosphatase activity in samples from maize‐ compared to willow‐planted soil. We conclude that antibiotic effects on the bacterial community structures are influenced by the antibiotic concentration and root influence.  相似文献   

3.
Biotic interactions affect the impact of potential plant growth promoting microorganisms in the rhizosphere, but their magnitude and fundamentals are often hardly known. In a pot experiment, two physiologically different strains of the ectomycorrhizal fungus Paxillus involutus (GUL and FRA) were tested separately and in combination with associated bacteria (Sphingomonas paucimobilis 1 L, Ralstonia pickettii 16 B, Sphingomonas sp. 23 L) on their effects on the growth of willows (Salix viminalis). Both P. involutus strains significantly increased the growth of the willows compared with non-inoculated plants, but the magnitude of this effect was significantly affected by the fungal strain. The P. involutus strain GUL with higher synthesis of auxin-like substances, acid phosphatases, siderophores and faster utilisation of yeast extract in vitro increased the willow growth in situ more effectively than strain FRA. Additionally, dual inoculation with the P. involutus strains GUL and FRA in combination with the associated bacteria promoted the willow growth, especially the combination with S. paucimobilis 1 L. This bacterial strain used effectively C sources which are common components of plant root exudates, e.g. glucose, sucrose, maltose and mannose as well as compounds synthesized by fungi, e.g. trehalose in vitro. We conclude that the analyses of fungal metabolites and of C source use of associated bacteria can successfully contribute to accelerate the selection of capable plant growth promoting combinations.  相似文献   

4.
In literature, it remains little explored the soil–plant relationships within Capsicum agroecosystem. We studied how chili peppers plants contribute to influence microbial diversity. Across the bulk and rhizosphere soils of three genotypes of Capsicum annuum, the structure, the diversity and the abundance of bacteria was evaluated by means of DNA-based culture-independent approach. Furthermore, 515 bacterial strains isolated from the bulk and rhizosphere soil, were used to investigate the effect of C. annuum on four plant growth promoting bacteria (PGPB) abilities. Our results indicated that the three genotypes influence differently the physical-chemical and microbial properties of soil around the roots. Bacterial abundance resulted in increasing with different trend rhizospheres to bulk soil ratio; however, bacterial diversity was significantly higher only in the rhizosphere of one genotype. Only the indolic compounds production was stimulated in the rhizosphere of the three cultivars. Inhibition of Fusarium oxysporum was stimulated just with one genotype, where 53 of rhizosphere isolates showed more than 10% of inhibition. 165 of isolates produced siderophores and the major part belonged to the high production level. Interactions between PGPB features revealed that anti-phytopathogenic activity was not associated with the others characteristics; however, phosphate solubilization was associated with both siderophores and indolic compounds productions.  相似文献   

5.
Although Phragmites australis is commonly planted in constructed wetlands, very little is known about its roots-associated bacterial communities, especially in wetlands used for the remediation of oil produced waters. Here, we describe the bacterial diversity, using molecular (illumina MiSeq sequencing) and cultivation techniques, in the rhizosphere soils of P. australis from an oil-polluted wetland in Oman. The obtained isolates were tested for their plant-growth promoting properties. Most sequences belonged to Proteobacteria, Bacteriodetes and Firmicutes. Sequences of potential hydrocarbon-degrading bacteria (e.g. Ochrobactrum, and Pseudomonas) were frequently encountered. All soils contained sequences of known sulfur-oxidizing (e.g. Thiobacillus, Thiofaba, Rhodobacter and Sulfurovum) and sulfate-reducing bacteria, although the latter group made up only 0.1% to 3% of total sequences. The obtained isolates from the rhizosphere soils were phylogenetically affiliated to Serratia, Acinetobacter, Xenorhabdus, Escherichia and Salmonella. All strains were able to solubilize phosphate and about half were capable of producing organic acids and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Around 42% of the strains had the ability to produce indole acetic acid and siderophores. We conclude that the rhizosphere soils of P. australis in oil polluted wetlands harbor diverse bacterial communities that could enhance the wetland performance through hydrocarbon degradation, nutrient cycling and supporting plant growth.  相似文献   

6.
Summary We tested 75 strains of Streptomyces spp. (25 taken from each environment of soil, rhizosphere, and mycorrhizosphere of pine, Pinus sylvestris L.) and all exhibited chitinolytic activity and hydrolysed gelatine and sodium caseinate in agar media. Enrichment of these media with glucose and NH4NO3 caused induction or stimulation of proteolytic Streptomyces spp. strains (80%) derived from root-free soil; inhibition of this activity was observed in most strains (92%) isolated from the root zone. The post-culture liquids of the rhizosphere strains cultured in the absence of glucose revealed a significantly higher proteolytic activity than those obtained from the root-free soil. The addition of glucose to the medium stimulated proteolytic activity in the post-culture broth of Streptomyces strains derived from soil and the mycorrhizosphere.  相似文献   

7.
We studied the effects of the application of organic (OM) and inorganic fertilizer (CF) on soil protease activity and proteolytic bacterial communities in rhizosphere and bulk soil on an experimental lettuce field in Hokkaido, Japan. The protease activity always was higher in soils of the OM than with the CF treatment, and also higher in the rhizosphere than in the bulk soil. We analyzed proteolytic bacterial communities by denaturing gradient gel electrophoresis (DGGE) of the alkaline metalloprotease (apr) and neutral metalloprotease (npr) genes. Most apr forms detected were closely related to apr of Pseudomonas fluorescens, and all npr variants closely resembled the gene of Bacillus megaterium. These results were consistent with findings from tests using cultured bacterial communities, indicating a high specificity of our PCR-DGGE for amplifying apr and npr genes. The community compositions of proteolytic bacteria were assessed by principal component analysis of the DGGE profiles. There were significant differences in the effects of CF and OM on the community compositions of apr- and npr-expressing bacteria, and the communities of the two types of bacteria played different roles in rhizosphere and bulk soil. We found significant correlations between the protease activity and the communities of the two types of bacteria. The results indicate that different proteolytic bacteria release different amounts or activities of protease, and that the composition of proteolytic bacterial communities may play a major role in determining overall soil protease activity.  相似文献   

8.
Pentachloronitrobenzene (PCNB) is an organochlorine fungicide that is mainly used in the prevention and control of diseases in crop seedlings. Microbial removal is used as a promising method for in-situ removal of many organic pesticides and pesticide residues. A short-term field experiment (1 year) was conducted to explore the potential role of a PCNB-degrading bacterial isolate, Cupriavidus sp. YNS-85, in the remediation of a PCNB-contaminated soil on which Panax notoginseng was grown. The following three treatments were used:i) control soil amended with wheat bran but without YNS-85, ii) soil with 0.15 kg m-2 of solid bacterial inoculum (A), and iii) soil with 0.30 kg m-2 of solid bacterial inoculum (B). The removal of soil PCNB during the microbial remediation was monitored using gas chromatography. Soil catalase and fluorescein diacetate (FDA) esterase activities were determined using spectrophotometry. In addition, cultivable bacteria, fungi, and actinomycetes were counted by plating serial dilutions, and the microbial biodiversity of the soil was analyzed using BIOLOG. After 1 year of in-situ remediation, the soil PCNB concentrations decreased significantly by 50.3% and 74.2% in treatments A and B, respectively, when compared with the uninoculated control. The soil catalase activity decreased in the presence of the bacterial isolate, the FDA esterase activity decreased in treatment A, but increased in treatment B. No significant changes in plant biomass, diversity of the soil microbial community, or physicochemical properties of the soil were observed between the control and inoculated groups (P<0.05). The results indicate that Cupriavidus sp. YNS-85 is a potential candidate for the remediation of PCNB-contaminated soils under P. notoginseng.  相似文献   

9.
Proteolytic bacterial communities, which mineralize organic nitrogen, play a key role in agricultural systems. In this study, alkaline metalloprotease (apr) gene fragments from proteolytic bacteria were investigated in bulk and rhizosphere paddy soil from four fields under organic management (for 2, 3, 5, and 9 years), and from one field under conventional management (for 2 years). We analyzed the abundance and structure of the proteolytic bacterial communities using real-time quantitative PCR and denaturing gradient gel electrophoresis. Our results showed that the abundance of proteolytic bacteria ranged from 1.57?×?108 to 8.02?×?108?copies/g of soil. In addition, the abundance of the proteolytic bacteria in the paddy soils under organic management was significantly higher than those in the paddy soil under conventional management. Moreover, the gene copy numbers in the rhizosphere soils were significantly higher than those in the bulk soils. The abundance of proteolytic bacteria tended to increase with the duration of organic management, with the highest abundance being found in the soil that had been under organic management for 5 years. However, the proteolytic bacteria communities in the paddy soils were not significantly affected by management practices. Phylogeny analysis showed that all gel bands obtained represented genes from Pseudomonas. Additionally, correlation analysis and canonical correspondence analysis showed that C/N, C, and N were important factors that influenced the abundance and community structure of the proteolytic bacteria. These results suggest that proteolytic bacteria are indicators in organic management systems, depolymerize organic N and hence maintain soil sustainability.

Abbreviations: CM: conventional management; OM: organic management; DGGE: denaturing gradient gel electrophoresis; qPCR: real-time quantitative PCR detecting system; COFCC: China organic food certification center; CCA: canonical correspondence analysis  相似文献   

10.
黄土丘陵沟壑区典型林地土壤微生物、酶活性和养分特征   总被引：4，自引：0，他引：4  
刘钊  魏天兴  朱清科  陈珏  赵彦敏 《土壤》2016,48(4):705-713
通过对陕西吴起县黄土沟壑区退耕还林地不同林分(沙棘、刺槐、油松、小叶杨)根际与非根际土壤养分、酶活性和微生物特征进行研究,比较4种典型林分及退耕草地“根际效应”及根际对养分的截留效应,评价根际效应对土壤特性产生不同改良效果,为黄土沟壑区退耕地人工林科学选择造林树种提供理论支持。研究表明:1根际与非根际土壤中有机质含量、有效磷含量、碱解氮含量和速效钾含量表现出显著差异,有机质、有效磷、速效钾含量均呈现明显的根际聚集现象。2根际土壤微生物数量和土壤酶活性总体高于非根际,仅油松样地中过氧化氢酶活性和小叶杨样地中脲酶活性根际低于非根际。3根际土壤中脲酶活性与细菌和真菌数量相关性达到显著水平,过氧化氢酶活性与真菌相关性达到显著水平;有机质含量与细菌、放线菌数量和脲酶活性相关性达到显著水平;碱解氮、有效磷含量均与细菌、真菌数量和脲酶活性相关性达到显著水平。在非根际土壤中,土壤养分含量与土壤微生物、土壤酶活性的相关性明显降低。4从土壤肥力综合水平看,根际土壤肥力水平综合得分总体上大于非根际土壤,其中根际土壤中沙棘小叶杨油松刺槐草地。沙棘能大幅度提高土壤肥力,具有较好的土壤改良效果。  相似文献   

11.
Inoculants are of great importance in sustainable and/or organic agriculture. In the present study, plant growth of barley (Hordeum vulgare) has been studied in sterile soil inoculated with four plant growth-promoting bacteria and mineral fertilizers at three different soil bulk densities and in three harvests of plants. Three bacterial species were isolated from the rhizosphere of barley and wheat. These bacteria fixed N2, dissolved P and significantly increased growth of barley seedlings. Available phosphate in soil was significantly increased by seed inoculation of Bacillus M-13 and Bacillus RC01. Total culturable bacteria, fungi and P-solubilizing bacteria count increased with time. Data suggest that seed inoculation of barley with Bacillus RC01, Bacillus RC02, Bacillus RC03 and Bacillus M-13 increased root weight by 16.7, 12.5, 8.9 and 12.5% as compared to the control (without bacteria inoculation and mineral fertilizers) and shoot weight by 34.7, 34.7, 28.6 and 32.7%, respectively. Bacterial inoculation gave increases of 20.3–25.7% over the control as compared with 18.9 and 35.1% total biomass weight increases by P and NP application. The concentration of N and P in soil was decreased by increasing soil compaction. In contrast to macronutrients, the concentration of Fe, Cu and Mn was lower in plants grown in the loosest soil. Soil compaction induced a limitation in root and shoot growth that was reflected by a decrease in the microbial population and activity. Our results show that bacterial population was stimulated by the decrease in soil bulk density. The results suggest that the N2-fixing and P-solubilizing bacterial strains tested have a potential on plant growth activity of barley.  相似文献   

12.
The organic compounds released from roots (rhizodeposits) stimulate the growth of the rhizosphere microbial community. They may be responsible for the differences in the structure of the microbial communities commonly observed between the rhizosphere and the bulk soil. Rhizodeposits consists of a broad range of compounds including root mucilage. The aim of this study was to investigate if additions of maize root mucilage, at a rate of 70 μg C g−1 day−1 for 15 days, to an agricultural soil could affect the structure of the bacterial community. Mucilage additions moderately increased microbial C (+23% increase relative to control), which suggests that the turnover rate of microorganisms consuming this substrate was high. Consistent with this, the number of cultivable bacteria was enhanced by +450%. Catabolic (Biolog® GN2) and 16S-23S intergenic spacer fingerprints exhibited significant differences between control and mucilage treatments. These data indicate that mucilage can affect both the metabolic and genetic structure of the bacterial community as shown by a greater catabolic potential for carbohydrates. We concluded that mucilage is likely to significantly contribute to differences in the structure of the bacterial communities present in the rhizosphere compared to the bulk soil.  相似文献   

13.
Plant growth–promoting rhizobacteria (PGPR) have been reported to stimulate the growth and yield of grain crops, particularly when nutrient supply is poor. However, the mechanisms underlying stimulation of plant growth may vary depending not only on growth conditions and crop management but also on plant and bacterial species. The present study assessed the effect of an inoculation with single or multiple PGPR strains on phosphorus (P)‐solubilization processes in the soil and on grain yield in wheat. Single inoculation with Bacillus subtilis OSU‐142, Bacillus megaterium M3, or Azospirillum brasilense Sp245 increased grain yield by 24%, 19%, and 19%, respectively, while a mixed inoculation with OSU‐142, M3, and Sp245 increased grain yield by 33% relative to noninoculated plants. Single inoculations with Paenibacillus polymyxa RC05 or Bacillus megaterium RC07 were less effective. Single or mixed treatments with OSU‐142, M3, and Sp245 increased the concentrations of the labile and moderately labile P fractions in rhizosphere soil. The growth‐stimulating effect of OSU‐142, M3, and Sp245 was also reflected by higher P concentrations in most plant organs. Among all inocula tested, the highest plant P acquisition was obtained in the presence of M3 and accompanied by the highest microbial P levels and the highest phosphatase activities in the rhizosphere soil. In conclusion, seed inoculation with mixed PGPR strains may effectively substitute for a part of P‐fertilizer application in extensive wheat production, and in particular M3 appears to improve the solubilization of inorganic soil P.  相似文献   

14.
 Five bacterial strains, one from each of the five known species of the plant growth-promoting bacteria (PGPB) Azospirillum (A. brasilense, A. lipoferum, A. amazonense, A. halopraeference, and A. irakense) were inoculated into two natural, semiarid soils (terra rosa and loessial sandy) from Israel, and two artificial soils constructed to simulate the native soils. Within 60 days, the populations of all five Azospirillum species declined significantly in a linear fashion, in both the native soils and in the homologous artificial soils. Increased levels of CaCO3, and fine and rough sand, had significant detrimental effects on the survival of the five Azospirillum species, whereas increased organic matter content improved survival. In contrast, when the bacterial strains were incubated in the rhizosphere of tomato seedlings grown in the artificial soils, manipulation of these soil variables had only a marginal effect on bacterial survival; all Azospirillum species survived well in the tomato rhizosphere under conditions that are otherwise detrimental. This study indicates that most cells of the strains of five known species of Azospirillum died out linearly over time in two semiarid soils, and that only the major soil components affected Azospirillum survival in soil. Because mortality was similar in native soils and in artificial homologous soils, artificial soils can be used to study the soil behavior of Azospirillum. Received: 9 April 1999  相似文献   

15.
Horizontal transfer of catabolic genes for pollutant degradation among rhizobacteria plays an important role in environmental bioremediation, but lacks support from field trial data. To address this problem, Pseudomonas fluorescens strain TP13 was inoculated into the soils of a phenol‐contaminated farmland on which tomato seedlings were growing in April 2009, 2010, 2011 and 2012. Results consistently showed that introduction of TP13 strain significantly reduced phenol content and increased plant biomass after 20 days, compared with controls. Strain TP13 was able to colonize the plant rhizosphere and the number of rhizosphere bacteria which were grown on phenol and contained the plasmids containing the gene encoding for catechol 2, 3‐dioxygenase (C23O) increased gradually in the later stages of the experiment. The increase in magnitude of the plasmid‐containing rhizosphere bacteria correlated well with plant biomass, while the number of plasmid‐containing rhizosphere bacteria and phenol content was strongly negatively correlated. Furthermore, six strains (T1‐T6) of rhizosphere bacteria were isolated and found to possess large plasmids containing identical C23O genes and similar HindIII restriction patterns. Sequence alignment showed that the C23O genes from strains T1‐T6 contained almost identical sequences and the sequence of the C23O of strain T1 was the same as that of strain TP13. These data indicated that the plasmids were transferred from strain TP13 to these rhizosphere bacteria and that horizontal gene transfer stimulated phenol degradation and plant growth in the contaminated farmland. This is an important finding for in situ remediation of contaminated farmland.  相似文献   

16.
The paper summarizes the results of a series of experiments on enumeration of N2-fixing bacteria (diazotrophs) and hormonal effects of Azospirillum on root development. Numbers of N2-fixing and N-heterotrophic bacteria were determined on the root (rhizoplane plus “inner” root surface) and in the rhizosphere soil (0–3 mm from the root surface) of Arrhenatherum elatius, other forage grasses and some herbaceous plant species. Pot experiments involved freshly collected soil from an unfertilized grassland area containing its natural population of N2-fixing bacteria. The MPN (most probable number) of diazotrophs in relation to the MPN of the total bacterial population was always lower on the root than in the rhizosphere soil, suggesting that diazotrophs were not selectively advantaged at the root surface. Supply of mineral nitrogen (NH4NO3) decreased the proportion of N2-fixing bacteria at the rhizoplane as well as in the rhizosphere soil. Similar results were obtained when N was supplied via the leaves. The data suggest that N2-fixing bacteria in the rhizosphere are poor competitors once they loose their competitive advantage of binding dinitrogen. Correspondingly, the increase in the MPN of the diazotrophs found during plant development was interpreted as a result of decreased available combined N in the rhizosphere. The proportion of N2-fixing bacteria relative to the total number of bacteria was generally below 1%. Considering the potential amount of substrate released from the roots and the substrate requirement of the bacterial population, N2-fixation was considered insignificant for plant growth under the given conditions. For the investigations on possible beneficial effects on plant development by bacterial hormones, Azospirillum brasilense was chosen because evidence suggests that amongst the soil bacteria releasing hormones, especially IAA, certain strains of this species are more important than other bacteria. Application of A. brasilense Cd (ATCC 29710) onto the roots of young wheat plants grown in soil increased the number of lateral roots, the total root length and the number of root hairs. Similar results were obtained after application of IAA. This suggests that IAA is an important factor responsible for the effects observed after inoculation with A. brasilense. The increase in root surface may improve acquisition of nutrients and enhance growth of plants. Another hormonal effect of A. brasilense was an increase in nodulation of Medicago sativa grown on agar. Again pure IAA resulted in a similar increase in nodule number. Increases in nodule number were only in part associated with a change in root morphology. Therefore an effect of IAA on the plant immanent regulation system for nodulation is likely.  相似文献   

17.
Re-vegetation of fly ash, the principal by-product of coal fired power stations, is hampered by its unfavourable chemical and physical properties for plant growth. In the present study, we evaluated the use of inoculation with a mycorrhiza-associated bacterial strain (Sphingomonas sp. 23L) to promote mycorrhiza formation and plant growth of three willow clones (Salix spp.) on fly ash from an over-burdened dump in a pot experiment. The high pHH2O (8.7) and low nitrogen content (Nt = 0.1 g kg−1) in combination with hydrophobicity of the particle surfaces caused low plant growth. Inoculation of the willows with Sphingomonas sp. 23L improved the nitrogen uptake by plants, increased plant growth and stimulated formation of ectomycorrhizae with an autochthonous Geopora sp. strain on all three willow clones. The ectomycorrhiza formed by the Geopora sp. was morphologically and anatomically described. The inoculation significantly increased the shoot growth of two Salix viminalis clones and the root growth of a S. viminalis x caprea hybrid clone. We conclude that inoculation with mycorrhiza promoting bacterial strains might be a suitable approach to support mycorrhiza formation with autochtonous site-adapted ectomycorrhizal fungi in fly ash and thereby to improve re-vegetation of fly ash landfills with willows.  相似文献   

18.
任改弟  张苗  张文越  郭德杰  马艳 《土壤》2022,54(4):740-749
通过盆栽试验,分析了不同来源有机物料(鸡粪、牛粪、菇渣)对菜用蚕豆生长和品质、根际土化学和生物学性状的影响。结果表明：(1)3种有机物料对蚕豆分枝数、荚干重、籽粒干重、大粒重、大粒蚕豆占比、籽粒淀粉含量均有积极作用,其中牛粪和菇渣能显著(P<0.05)提高大粒蚕豆占比,鸡粪能显著(P<0.05)提高二粒荚和三粒荚的占比,并且对籽粒淀粉含量的提升效果最为明显(比对照增加69.1%);(2)3种有机物料增加了根际土中细菌、真菌数量,显著(P<0.05)提高了根际土中性转化酶、脲酶、酸性磷酸酶、多酚氧化酶活性(除牛粪使中性转化酶活性提高不显著外),其中鸡粪对细菌数量、中性转化酶活性、脲酶活性的提高程度均最大;(3)鸡粪能显著(P<0.05)增加根际土有机碳、全氮、NH4+-N含量,牛粪、鸡粪能显著(P<0.05)提高土壤p H。大粒蚕豆占比与土壤酸性磷酸酶活性、有效磷含量呈显著正相关。蚕豆淀粉含量与细菌数量、中性转化酶活性、有机碳、全氮、NH4+-N含量呈显著正相关,这说明有...  相似文献   

19.
Available phosphorus is limiting in most cultivable soils in several parts of India, including Rajasthan. Four phosphate-solubilizing bacterial strains viz. Pseudomonas fluorescens BAM-4, Burkholderia cepacia BAM-6, B. cepacia BAM-12 and Aeromonas vaga BAM-77 were isolated from the rhizosphere of pearl millet (Pennisetum glaucum, cv. Raj 171), mung bean (Phaseolus aureus, cv. RMG 492) and sesame (Sesamum indicum, cv. RT 46). To the best of our knowledge, this is the first report on phosphate solubilization by Aeromonas vaga. Seed inoculation of mung bean with or without tricalcium phosphate (TCP) was performed to study the effect of single and dual bacterial inoculations in pot trials having sterilized sandy loam soil, and was found to enhance the growth and yield of plants. The results were on a par with chemical fertilizer, single superphosphate (SSP) and commercial biofertilizers, PSB (Bacillus polymyxa) and MC (Pseudomonas striata), used as standard reference. Addition of TCP to soil gave better results and dual inoculation was more effective than single inoculation of bacteria. Among the four strains studied, A. vaga and P. fluorescens were found to be more valuable as single inoculants in terms of plant growth, whereas in combination treatments, P. fluorescens along with B. cepacia and A. vaga performed very well both in the presence and absence of TCP.  相似文献   

20.
Soil microbial community composition is determined by the soil type and the plant species. By sequencing the V3-V4 region of the bacterial 16S rRNA gene amplicons, the current study assessed the bacterial community assemblage in rhizosphere and bulks soils of wild (Glycine soja) and cultivated (Glycine max) soybeans grown in the suspensions of three important soil types in China, including black, red and soda-saline-alkali soils. The alpha-diversity of the bacterial community in the rhizosphere was significantly higher than that of the bulk soils suggesting that bulk soil lacks plant nurturing effect under the current study conditions. Black and red soils were enriched with nitrifying and nitrogen-fixing bacteria but the soda-saline-alkali soil suspension had more denitrifying bacteria, which may reflect agronomic unsuitability of the latter. We also observed a high abundance of Bradyrhizobium and Pseudomonas, enriched cellulolytic bacteria, as well as a highly connected molecular ecological network in the G. soja rhizosphere soil. Taken all, the current study suggest that wild soybeans may have evolved to recruit beneficial microbes in its rhizosphere that can promote nutrients requisition, biostasis and disease-resistance, therefore ecologically more resilient than cultivated soybeans.  相似文献   

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