Inoculation Treatments Research Articles

The Effects of Root Endophytic and Arbuscular Mycorrhizal Fungi on Growth and Curcumin Content of Temulawak (Curcuma xanthorrhiza)

Temulawak (Curcuma xanthorrhiza) is known to be used as ingredient in Jamu and traditionally utilized to cure a range of illness. The global market demand for the rhizome of the temulawak affecting the urgency of sustainable rizhome production. The aim of this research was to analyze the effects of root endophytic and arbuscular mycorrhizal fungi on growth and rhizome curcumin content of the temulawak. There were five fungal inoculation treatments on C. xanthorrhiza seedling grown in sterilized and unsterilized growth media. They were root endophytic fungi A. niger (A), Glomus sp. (G), combination of A. niger and AMF Glomus sp. applied at the same time (GA) and at different time (G-A) and control. The experiment was conducted under greenhouse condition. The plant growth parameters, fungal colonization, and rhizomes curcumin content were measured. The result showed that there was a significant interaction between fungal inoculation and control treatments. In general, fungal inoculation on both sterilized and unsterilized growth media increased the plant growth and rhizomes curcumin content. On the sterilized growth media, C. xanthorrhiza inoculated by A. niger showed the best growth parameter. On the other hand, the best growth parameter on the unsterilized media was showed by C. xanthorrhiza inoculated by mixed fungal inoculums. The highest amount of curcumin content was showed by C. xanthorrhiza inoculated by Glomus sp. as a single inoculation.

Analyzing the effect of inoculant addition on the solidification of ductile cast irons using thermal analysis

PurposeThe final properties of ductile iron are decided by the inoculant processing while pouring the melt. The shape and size of nodules generated during solidification are of paramount importance in solidification of ductile cast iron. The purpose of this study is to examine the effect of different inoculant addition on the solidification of ductile cast iron melt through thermal analysis.Design/methodology/approachThermal analysis has recently grown as a tool for modeling the solidification behavior of ductile cast irons. Iron properties will be predicted by analyzing the cooling curve patterns of the melts and predicting the related effectiveness of inoculant processing. In this study, thermal analysis is used to evaluate the need for inoculation.FindingsThe amount and type of inoculation will affect the amount of undercooling during the solidification of ductile cast iron. It is found that the addition of 0.1 to 0.4 Wt.% inoculant lowers the austenite dendrite formation starting temperature while increasing the eutectic freezing temperature. Microstructure analysis revealed that the addition of inoculation increases the nodule count from 103 to 242 nodules. The beneficial effects of inoculation are sustained by an improved graphitization factor, which shows the formation of graphite nodules in the second phase of the eutectic reaction.Originality/valueThe inoculation treatment has improved metallurgical occurrences such as carbide to graphite conversion, graphite microstructure control, graphite nodule count at the start of solidification and the last stage of solidification, which determines the soundness of casting. The foundry industry can follow these steps for monitoring the solidification of ductile iron castings.

AMF Inoculum Enhances Crop Yields of Zea mays L. 'Chenghai No. 618' and Glycine max L. 'Zhonghuang No. 17' without Disturbing Native Fugal Communities in Coal Mine Dump.

For the agricultural development of dumps, increase in land use efficiency and protection of food security, to verify the safety, efficacy and sustainability of field-applied arbuscular mycorrhizal fungi (AMF) inoculum, and to exclude the risk of potential biological invasion, in this study, we determined the effect of AMF inoculation and intercropping patterns (maize-soybean) on the temporal dynamics of soil parameters, native AMF communities and crop yields. AMF communities were analyzed using Illumina MiSeq. A total of 448 AMF operational taxonomic units (OTUs) belonging to six genera and nine families were identified. AMF inoculation treatment significantly improved the yield of intercropping maize and increased the content of available phosphorus. AMF diversity was significantly influenced by cropping pattern and growth stage, but not by the inoculation treatment. Inoculation altered the AMF community composition in the early growth stage and facilitated a more complex AMF network in the early and late growth stages. These results indicate that AMF inoculation affects native AMF only in the early stage, and its impact on yield may be the consequence of cumulative effects due to the advantages of plant growth and nutrient uptake in the early stage.

Plant-growth promotion by proteobacterial strains depends on the availability of phosphorus and iron in Arabidopsis thaliana plants.

Phosphorus (as phosphate, Pi) and iron (Fe) are critical nutrients in plants that are often poorly available in the soil and can be microbially affected. This work aimed to evaluate how plant-rhizobacteria interaction changes due to different Pi or Fe nutritional scenarios and to study the underlying molecular mechanisms of the microbial modulation of these nutrients in plants. Thus, three proteobacteria (Paraburkholderia phytofirmans PsJN, Azospirillum brasilense Sp7, and Pseudomonas putida KT2440) were used to inoculate Arabidopsis seeds. Additionally, the seeds were exposed to a nutritional factor with the following levels for each nutrient: sufficient (control) or low concentrations of a highly soluble source or sufficient concentrations of a low solubility source. Then, the effects of the combinatorial factors were assessed in plant growth, nutrition, and genetic regulation. Interestingly, some bacterial effects in plants depended on the nutrient source (e.g., increased aerial zones induced by the strains), and others (e.g., decreased primary roots induced by Sp7 or KT2440) occurred regardless of the nutritional treatment. In the short-term, PsJN had detrimental effects on plant growth in the presence of the low-solubility Fe compound, but this was not observed in later stages of plant development. A thorough regulation of the phosphorus content was detected in plants independent of the nutritional treatment. Nevertheless, inoculation with KT2440 increased P content by 29% Pi-deficiency exposed plants. Conversely, the inoculation tended to decrease the Fe content in plants, suggesting a competition for this nutrient in the rhizosphere. The P-source also affected the effects of the PsJN strain in a double mutant of the phosphate starvation response (PSR). Furthermore, depending on the nutrient source, PsJN and Sp7 strains differentially regulated PSR and IAA- associated genes, indicating a role of these pathways in the observed differential phenotypical responses. In the case of iron, PsJN and SP7 regulated iron uptake-related genes regardless of the iron source, which may explain the lower Fe content in inoculated plants. Overall, the plant responses to these proteobacteria were not only influenced by the nutrient concentrations but also by their availabilities, the elapsed time of the interaction, and the specific identities of the beneficial bacteria. Graphical AbstractThe effects of the different nutritional and inoculation treatments are indicated for plant growth parameters (A), gene regulation (B) and phosphorus and iron content (C). Figures created with BioRender.com with an academic license.

Production of potato seed tubers under the effect of Trichoderma sp. and rhizobacteria in greenhouse conditions

Potato (Solanum tuberosum L.) is one of the main crops in the Andean region and due to environmental aspects, the use of biocontrol agents is considered a safe way to produce potato seed tubers.The objective of the study was to evaluate potato inoculation with Trichoderma sp. as a matrix and rhizobacteria Bacillus simplex and Azotobacter sp. on the growth of potato seedlings from in vitro culture, for the production of seed tubers in a greenhouse. The inoculation of microorganisms was carried out in pots, using five potato genotypes for processing. The inoculation treatments were: control, Trichoderma sp., Trichoderma sp. + Azotobacter sp., Trichoderma sp. + Bacillus simplex, Trichoderma sp. + B. simplex + Azotobacter sp. The potato genotypes were cv. Unica (CIP392797.22), cv. Bicentenaria, the advanced clones CIP 396311.1, CIP 399101.1, and the experimental clone UH-09 from the Universidad Nacional José Faustino Sánchez Carrión. A completely randomized design was used, under a factorial arrangement and comparisons between treatments were made at p<0.05. All inoculant treatments exceeded the control in number and weight of tubers per plant as well as in tuber size. Inoculations of Trichoderma sp. alone or with Azotobacter sp. increased plant height, number of leaves per plant and vegetative uniformity; inoculations with the Trichoderma sp. + B. simplex + Azotobacter sp. consortium, improved the dry weight of the foliage, number of shoots per plant and vegetative vigor. There were significant interactions between potato genotypes and inoculant treatments for plant uniformity, vegetative vigor, and the foliage's dry weight. Coinoculation with Trichoderma sp. and some bacterial strains promote the growth of in vitro potato seedlings, increasing the size and weight of the seed tubers and plant biomass, indicating an interrelation between fungi and bacteria that influence the production of potatoes in a greenhouse.

A Study of the Mechanisms and Kinetics of the Localized Corrosion Aggravation of Ductile Iron in a Harsh Water Quality Environment

Ductile iron is a high-strength cast iron material. The spherical graphite obtained by inoculation treatment effectively improves the mechanical properties of cast iron, resulting in higher strength than carbon steel. However, severe corrosion may occur under specific circumstances, especially in thermal water pipelines. In this paper, the corrosion mechanisms at the main defective points of ductile iron were investigated using microscopic morphological characterization after accelerated tests combined with numerical simulations. The influence law of each environmental factor on the corrosion kinetics of ductile iron in a complex water quality environment was studied using dynamic potential polarization tests. The results showed that the main causative factors leading to the increased corrosion of ductile iron were the presence of tail-like gaps on its surface, and the crescent-shaped shrinkage and loosening organization around the graphite spheres. After mechanical treatment was applied to eliminate the obvious defects, the number of corrosion pits was reduced by 41.6%, and the depth of the pits was slowed down by 40% after five days. By comparison, after ten days, the number of pits was reduced by 51%, and the depth of the pits was slowed down by 50%. The dynamic potential polarization test results show that the dissolved oxygen concentration has the greatest influence on the corrosion of ductile iron in the simulated water environment; meanwhile, the water hardness can slow down the corrosion of ductile iron. The relative influence of each environmental factor is as follows: dissolved oxygen concentration > temperature > immersion time > water hardness > pH > Cl−.

Effect of Burkholderia ambifaria LK-P4 inoculation on the plant growth characteristics, metabolism, and pharmacological activity of Anoectochilus roxburghii.

Plant growth-promoting bacteria (PGPB) represents a common biological fertilizer with remarkable effect in improving crop production and environmental friendliness. In the present work, we presented a detailed characterization of plant morphology and physiology, metabolism, and pharmacological activity of A. roxburghii between Burkholderia ambifaria LK-P4 inoculation and un-inoculation (CK) treatment by routine analytical techniques (include microscopy and enzymatic activity assays and so on) coupled with metabolomics approaches. Morphological and physiological results showedthat the P4 bacteria could significantly increase plant stomatal density, freshweight, survival rate,and the content of total flavonoids in leaves but reducethe amount of free amino acid. Furthermore, metabolite data showed that fatty acids (linoleic acid, linolenic acid, stearic acid) and active substance (kyotorphin and piceatannol) were specifically up-regulated in P4 inoculation. It was also demonstrated that the differential metabolites were involved in citrate cycle, glyoxylate and dicarboxylate metabolism, and biosynthesis of unsaturated fatty acids pathway. In addition, pharmacological efficacy found that A. roxburghii under P4 inoculation can significantly decrease (p < 0.05) blood glucose levels and protect the organs of mice with similar effect of Glibenclamide tablets. Overall, it can be seen that the exogenous P4 bacteria can promote the growth and increase content of special metabolites in A. roxburghii. This study provided theoretical basis and supported for the high-yield and high-quality bionic cultivation of A. roxburghii.

The yield of maize-soybean intercropping on Mycorrhizal inoculation treatment and plant nutrition provision in suboptimal land North Lombok, Indonesia

Mycorrhizal inoculation and plant nutrition have an important role in increasing the yield of maize-soybean intercropping in suboptimal land. The experimental design used was a factorial randomized block design with two factors, the first factor was AMF inoculation which consisted of two levels, namely M0 = without AMF inoculation and M1 = with AMF inoculation, and the second factor was plant nutrition treatment. with four levels, namely U0 = without the addition of nutrients, U1 = with the addition of 100% dose of inorganic fertilizer (maize = urea 300 kg ha-1 and Phonska 200 kg ha-1, soybean = 60 kg ha-1 Urea and 120 kg ha-1 Phonska), U2 = with the addition of 100% dose of cattle manure and U3 = with the addition of 50% dose of cattle manure (6 t ha-1) plus 50% dose of inorganic fertilizer (maize = urea 150 kg ha-1 and Phonska 100 kg ha-1, soybean= 30 kg ha-1 Urea and 60 kg ha-1 Phonska). The results showed that AMF inoculation treatment and application of 50% inorganic fertilizer plus 50% organic fertilizer gave the highest yield with maize grain weight of 4.3 tons ha-1 and soybean grain weight of 0.5 tons ha-1.

Invader-induced soil abiotic and biotic conditions have little impact on the competitive interactions between a native and an invasive legume

• No competition occurred between native Psoralea pinnata and invasive A. saligna . • Each legume species associated with different rhizobia and used divergent nitrogen sources. • Australian rhizobia were naturally present in pristine Fynbos soils. • Acacia invasion and spread may not be limited by rhizobium availability in Fynbos soils. Invasive Australian acacias cause substantial biodiversity impacts in South Africa's Core Cape Subregion (CCR) via positive plant-soil feedbacks, driven by high growth rates and leaf litter input by these legumes and their associations with nitrogen-fixing rhizobia. However, it is unclear whether acacia-induced soil abiotic conditions, or the association between acacias and different types of rhizobia, or both, are driving the invasive performance of acacias. Here we aim to determine how familiar (i.e., Australian) vs. novel (i.e., South African) rhizobium associations and acacia leaf litter affect competition between the invasive Acacia saligna (Labill.) H.L.Wendl. and native Psoralea pinnata L.. We grew these two legumes alone and together in pots containing Psoralea -conditioned soils. Seedlings grown alone were subjected to Australian bradyrhizobia inoculum treatments, while seedlings grown in mixture received a combination of inoculum and topsoil conditioned by acacia leaf litter in a fully factorial design. We found that neither the addition of Australian rhizobia, nor acacia-conditioned topsoil, enhanced the performance of A. saligna . Surprisingly, these treatments also did not hinder P. pinnata ’s performance relative to that of A. saligna . Next generation sequencing (NGS) data revealed that each legume species associated with distinct (and familiar) rhizobia, regardless of inoculum treatment. Acacia saligna primarily met its nitrogen requirements by utilising soil nitrogen, while P. pinnata obtained much of its nitrogen via biological fixation. This apparent differentiation in nitrogen acquisition, coupled with the unique rhizobial associations of the two species, may explain the absence of strong asymmetric competition between them. This may also explain why P. pinnata is able to persist under Acacia invasion in the field and suggests that this native legume is a good candidate for restoring acacia-invaded habitats.

Influence of am fungus funneliformis mosseae and k solubilizing bacterium bacillus mucilaginosus on the growth of tomato seedlings raised in pro trays Running head: influence of am fungi and ksb on the growth of tomato seedlings.

Raising vegetable seedlings in pro trays is becoming an innovative approach to produce quality seedlings in horticulture. The present investigation was conducted to evaluate the effect of AMF Funneliformis mosseae and K solubilizing bacterium Bacillus mucilaginosus singly and together in enhancing the growth of tomato seedlings raised in pro trays under polyhouse conditions. Different growth parameters like shoot and root length, total seedling length, stem diameter, dry weight of seedlings, biovolume index, plant strength, vigourindex, macro and micro nutrientuptake, mycorrhizal root colonization and the population of B. mucilaginosus in the root zone soil were monitored. Significantly higher shoot length,root length, stem diameter and biovolume indexwere recorded in the treatments inoculated with F. mosseae alone followed by B. mucilaginosus alone. Most of the plant growth parameters were significantly less in the dual inoculation treatment with F. mosseae + B. mucilaginosus compared to single inoculation with either of them. This brings out the negativeinfluence of the two inoculants on each other leading to a reducedeffect on plant growth.

Improved effects of combined application of nitrogen-fixing bacteria Azotobacter beijerinckii and microalgae Chlorella pyrenoidosa on wheat growth and saline-alkali soil quality

Soil salinization seriously affects crop yield and soil productivity. The application of bacteria and microalgae has been considered as a promising strategy to alleviate soil salinization. However, the effect of bacteria-microalgae symbiosis on saline-alkali land is still unclear. This study evaluated the effects of Azotobacter beijerinckii, Chlorella pyrenoidosa, and their combined application on the wheat growth and saline-alkali soil improvement. The results showed that, among all the treatments, A. beijerinckii + live C. pyrenoidosa combined inoculation group (BA) had the best effect on increasing wheat plant biomass, improving salt tolerance, and improving soil fertility. The dry weight of wheat plant in the BA group increased by 66.7%, 17.4%, and 35.0%, respectively, compared with the control group (CK), A. beijerinckii inoculation group (B), and live C. pyrenoidosa inoculation group (A). The total nitrogen content of wheat plant in the BA group increased by 69.5%, 76.7%, and 71.1%, compared with the CK, B, and A group. The proline content of wheat plant in the BA group was 100% higher than that in the CK group. The N/P ratio and K/Na ratio of wheat plant increased by 157% and 12.9% in the BA group compared with the CK group, respectively, which was more conducive to alleviating nitrogen limitation and salt stress. The A. beijerinckii + live C. pyrenoidosa inoculation treatment better reduced soil pH and improved the availability of phosphorus in soil. This study illustrated the comprehensive application prospects of bacteria-microalgae interactions on wheat growth promotion and soil improvement in saline-alkali land, and provided a new effective strategy for improving saline-alkali soil quality and increasing crop productivity.

Azospirillum brasilense and Zinc Rates Effect on Fungal Root Colonization and Yield of Wheat-Maize in Tropical Savannah Conditions.

A successful microbial inoculant can increase root colonization and establish a positive interaction with native microorganisms to promote growth and productivity of cereal crops. Zinc (Zn) is an intensively reported deficient nutrient for maize and wheat production in Brazilian Cerrado. It can be sustainably managed by inoculation with plant growth-promoting bacteria and their symbiotic association with other microorganisms such as arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE). The objective of this study was to evaluate the effect of Azospirillum brasilense inoculation and residual Zn rates on root colonization and grain yield of maize and wheat in succession under the tropical conditions of Brazil. These experiments were conducted in a randomized block design with four replications and arranged in a 5 × 2 factorial scheme. The treatments consisted of five Zn rates (0, 2, 4, 6 and 8 kg ha-1) applied from zinc sulfate in maize and residual on wheat and without and with seed inoculation of A. brasilense. The results indicated that root colonization by AMF and DSE in maize-wheat cropping system were significantly increased with interaction of Zn rates and inoculation treatments. Inoculation with A. brasilense at residual Zn rates of 4 kg ha-1 increased root colonization by AMF under maize cultivation. Similarly, inoculation with A. brasilense at residual Zn rates of 2 and 4 kg ha-1 reduced root colonization by DSE under wheat in succession. The leaf chlorophyll index and leaf Zn concentration were increased with inoculation of the A. brasilense and residual Zn rates. The inoculation did not influence AMF spore production and CO2-C in both crops. The grain yield and yield components of maize-wheat were increased with the inoculation of A. brasilense under residual Zn rates of 3 to 4 kg ha-1 in tropical savannah conditions. Inoculation with A. brasilense under residual Zn rates up to 4 kg ha-1 promoted root colonization by AMF and DSE in the maize cropping season. While the inoculation with A. brasilense under 2 and 4 kg ha-1 residual Zn rates reduced root colonization by AMF and DSE in the wheat cropping season. Therefore, inoculation with A. brasilense in combination with Zn fertilization could consider a sustainable approach to increase the yield and performance of the maize-wheat cropping system in the tropical savannah conditions of Brazil.

First Report of Flower Stalk Wilting Caused by Rhizopus oryzae on Chinese cabbage in China.

Chinese cabbage (Brassica rapa L. ssp. pekinensis) is one of the main biennial vegetables in China and its flowers can be produced in the second year. In May 2021, approximately 50% of the flower stalks of Chinese cabbage wilted in a field in Laizhou, China. Water-soaked lesions were first observed on the lateral shoots of flower stalks, leading to wilting at a later stage. Small diseased tissues were excised from the margin of lesions, surface disinfected in 75% alcohol, rinsed in distilled water twice, and transferred onto potato dextrose agar (PDA) medium for incubation at 28 ℃. Five fungal isolates were obtained using single spore isolation method. The fungal colonies were initially white and became gray or black within 5 days. The columella was globose to subglobose and 82.86±5.25 μm (n=5) in diameter; sporangiophores were smooth-walled, simple or branched; the globose sporangia were 86.06±15.37 μm (n=5) in diameter and black; the sporangiospores were subglobose and abundant and 5.23±0.98 μm (n=5) in diameter; and the rhizoids were dark brown and 5.69±1.82 μm (n=5) wide. A cetyl tri-methyl ammonium bromide method was used to extract DNA from 3-day-old hyphae (Ausubel et al. 1987). PCR was performed for ITS (White et al. 1990), the RNA polymerase II large subunit (RPB1) gene (Voigt et al. 2000) and the actin (ACT) gene (Stiller et al. 1997). The DNA sequences of the five isolates were identical, therefore, the sequence of Isolate RO21 was submitted to GenBank. According to BLAST search, the ITS (MZ452687), RPB1 (OK431470), and ACT (OK431471) sequences showed 99.66% similarity to Rhizopus oryzae Strain CBS 112.07 (NR103595), 100% to Strain CBS 127.08 (KJ566325) and 100% to Strain CBS 102660 (KJ551423), respectively. A neighbor-joining phylogenetic tree was reconstructed based on the ITS of Isolate RO21 and 14 other Rhizopus species sequences obtained from GenBank. Isolate RO21 was found to be most closely related to R. oryzae and far from other species. Based on morphological and phylogenetic characteristics, Isolate RO21 was identified as R. oryzae (Dolatabadi et al. 2014, Kwon et al. 2015, Palemón-Alberto et al. 2020). Sporangiospores were harvested from 5-day-old PDA cultures, suspended in sterilized distilled water, adjusted to 106 spores/ml and amended with 0.1% Tween-80. Chinese cabbage inbred line "A54-1" was inoculated near the middle of the flower stalk by applying 20 μl of spore suspension (106 spores/ml) to each of three sites wounded using a sterilized knife or to the unwounded site. Sterilized distilled water was used as the control. Forty flower stalks (20 for the inoculation treatment and the rest for the control) selected from ten plants were used for pathogenicity test. All plants were incubated in a growth chamber at 28/22 °C (day/night), with 80 to 90% of relative humidity. Wilting symptoms similar to those in the field were observed in the wounded flower stalks after 5 days and in the non-wounded flower stalks after 15 days. All control flower stalks remained asymptomatic. The fungus was re-isolated from the artificially infected flower stalks and identified as R. oryzae by morphological characteristics and sequencing to fulfill the Koch's postulates. To our knowledge, this is the first report that R. oryzae causes flower stalk wilting on Chinese cabbage in China. The results can provide the basis for future studies on the occurrence, prevention and management of this disease.

Revisiting the effects of an inoculation treatment on psychological reactance: a conceptual replication and extension with self-report and psychophysiological measures

Abstract Research published by Richards and Banas and Richards et al. demonstrated that an inoculation treatment given to participants prior to their exposure to a series of freedom-threatening persuasive health messages mitigates audiences’ freedom-threat perceptions, state psychological reactance, and behavioral intentions. We sought to conceptually replicate the studies by Richards and Banas and Richards et al. with a sample of ever-vapers who were either assigned to an inoculation condition or control condition and then exposed to a series of dogmatic anti-vaping messages while psychophysiological responses were recorded. In doing so, we also sought to replicate the pattern of results observed by Clayton et al. and Clayton who used the same stimuli, methods, and measures. The results from our study provided a successful conceptual replication of each of these studies, with a few exceptions that are discussed. This study provides greater confidence in recent psychological reactance findings and the efficacy of an inoculation treatment for circumventing psychological reactance.

Structural breakdown and phytotoxic assessments of PE degradation through acid hydrolysis, starch addition and Pseudomonas aeruginosa bioremediation

Vast amounts of plastic waste are causing serious environmental issues and urge to develop of new remediation methods. The aim of the study is to determine the role of inorganic (nitric acid), organic (starch addition), and biological (Pseudomonas aeruginosa) soil amendments on the degradation of Polyethylene (PE) and phytotoxic assessment for the growth of lettuce plant. The PE-degrading bacteria were isolated from the plastic-contaminated soil. The strain was identified as Pseudomonas aeruginosa (OP007126) and showed the highest degradation percentage for PE. PE was pre-treated with nitric acid as well as starch and incubated in the soil, whereas P. aeruginosa was also inoculated in PE-contaminated soils. Different combinations were also tested. FTIR analysis and weight reduction showed that though nitric acid was efficient in degradation, the combined application of starch and bacteria also showed effective degradation of PE. Phytotoxicity was assessed using morphological, physiological, and biochemical parameters of plant. Untreated PE significantly affected plants' physiology, resulting in a 45% reduction in leaf chlorophyll and a 40% reduction in relative water content. It also had adverse effects on the biochemical parameters of lettuce. Bacterial inoculation and starch treatment mitigated the harmful impact of stress and improved plants' growth as well as physiological and biochemical parameters; however, the nitric treatment proved phytotoxic. The observed results revealed that bacteria and starch could be effectively used for the degradation of pre-treated PE.

Synergistic effects of nitrogen and plant growth-promoting rhizobacteria inoculation on the growth, physiological traits and nutrient absorption of intercropped Eucalyptus urophylla × Eucalyptus grandis and Dalbergia odorifera

Key messageLegume/nonlegume intercropping systems equipped with moderate nitrogen (N) application and PGPR inoculation could be exploited in eucalyptus growing areas and degraded land as an ecologically sustainable system to avoid excessive fertilization and enhance nitrogen use efficiency.Hazardous nitrogenous fertilizers in eucalyptus monocultures are challenging for the balance between eucalyptus wood production and ecological service functions. To assess whether plant growth-promoting rhizobacteria (PGPR) inoculation coupled with N application may improve plant growth by increasing biomass, photosynthesis, soil nutrient supply, and nutrient uptake capacity in the intercropping system. A pot experiment was performed to evaluate the synergistic effects of N application and N-fixing PGPR on growth, physiological parameters, N accumulation and nitrogen use efficiency (NUE) in intercropped Eucalyptus urophylla × Eucalyptus grandis (E. urophylla × E. grandis) and Dalbergia odorifera (D. odorifera). N fertilization positively influenced the plant height, dry matter yield, photosynthetic characteristics, N accumulation and nitrate reductase activity of E. urophylla × E. grandis under both inoculations. The growth and physiological traits of D. odorifera improved under the N2 (6 g N pot−1) application level. E. urophylla × E. grandis inoculated with Rhizobium japonicum IOC 113-2 showed higher values for plant height, biomass accumulation, N accumulation and photosynthesis with N fertilization, but the growth and physiological parameters of D. odorifera responded differentially to different inoculation treatments. The results demonstrated that an appropriate N supply in combination with N-fixing PGPR inoculation of legumes could increase nutrient absorption, NUE and yield advantages in intercropped E. urophylla × E. grandis and D. odorifera; thus, this method could be recommended as an alternative planting system under N-limited conditions in agroecosystems.

Between‐partner concordance of vertically transmitted gut microbiota diminishes reproductive output in the dung beetle Onthophagus taurus

AbstractIn this study, we explored the potential contribution of the gut microbiome to reproductive isolation in tunnelling dung beetles, using Onthophagus taurus (Schreber, 1759) and its sister species O. illyricus (Scopoli, 1763) as a model system (Coleoptera: Scarabaeidae: Scarabaeinae: Onthophagini). Gut microbiota play critical roles in normative development of these beetles, and are vertically inherited via a maternally derived faecal pellet called the pedestal. We first compared the developmental outcomes of individuals reared with pedestals derived from either the same or the sister species (Self and Cross inoculation treatments, respectively). We then crossed the resulting adult O. taurus in three combinations (Self female X Self male; Self female X Cross male; Cross female X Self male). We predicted that if the vertically transmitted gut microbiome plays a role in reproductive isolation by facilitating species recognition, the Self X Self line would have improved reproductive outcomes compared to the lines in which partners had mismatched gut microbiomes. Instead, we found that between‐partner concordance of maternally transmitted gut microbiota resulted in fewer offspring, and that this reduction was due to partial pre‐copulatory isolation as evidenced by reduced sperm transfer in the Self X Self line. This pattern is consistent either with microbiome‐mediated familiarity/kin recognition, or with absence of mate choice in crosses with mismatched microbiomes. We discuss our results in the light of recent research on the influence of extracellular microbial symbionts over insects' mating preferences.

Effects of microbial inoculum on microbial community and enzyme activity involved in nitrogen-sulfur metabolism during sewage sludge composting

The purpose of this study was to access the effects of thermotolerant nitrifying microorganisms and sulfur-oxidizing bacteria on microbial community and enzyme activity involved in nitrogen‑sulfur metabolism during laboratory-scale sewage sludge (SS) composting，and to do a microbial-environmental factor association analysis to promote composting key species for nitrogen‑sulfur transformation in the body. The microbial community structure and the activities variation of six key enzyme involved were detected. The microbial inocula added had little impact on the diversity of the microbial community but changed its succession direction, and the abundance of Actinobacteria was decreased obviously of inoculation treatment (TR). The three dominant genera and indicator species in TR were significantly correlated with the conversion of nitrogen and sulfur. The addition of microbial inocula promoted the conversion of nitrogen and sulfur in SS compost, and increased the activities of the key enzymes and the microbial genera involved in nitrogen‑sulfur conversion. In other words, the nitrification and sulfur oxidation were enhanced simultaneously in the later stage of composting in TR.

Enhanced Root and Stem Growth and Physiological Changes in Pinus bungeana Zucc. Seedlings by Microbial Inoculant Application

Background and Objectives: As an extensively used tree species in landscaping and afforestation in China, lacebark pine (Pinus bungeana Zucc.) seedlings are in high demand. However, the small number of fine roots and the low growth rate of lacebark pine seedlings increase the risks encountered during transplant and extend the nursery time for outplanting. We aimed to find out whether a microbial inoculant would promote root growth and accordingly, shorten the nursery cultivation time. Materials and Methods: One-year-old lacebark pine seedlings were treated with the inoculant Bacillus subtilis 8–32 six times from June to September. At each application time, five treatments of undiluted microbial inoculants (UM), 30 times diluted microbial inoculants (30 DM), 40 times diluted microbial inoculants (40 DM), 50 times diluted microbial inoculants (50 DM), and distilled water as a control (CTRL) were administered to the seedlings. In the end, all the seedlings were harvested to measure the root growth, aboveground growth, and the physiological indices. Results: Root and stem growth was enhanced by the inoculants in terms of the increased number of root tips, the length and surface area of the roots, the biomass of the roots and stems, as well as the increase in height and basal stem diameter. The chlorophyll a/b of the needles was increased, in spite of the fact that the total chlorophyll content was decreased by the microbial inoculant treatments at the end of the growth phase. Meanwhile, the maximum photochemical efficiency (Fv/Fm) of the needles was increased by the inoculant treatments. The soluble sugar content was additionally translocated into the stems in the UM treatment, suggesting the change in carbon allocation. The content of available potassium, phosphorus, and ammonium nitrogen in the potting soil was increased in the 30 DM group, and the content of soil organic matter was increased in all the inoculant treatments. Conclusions: The microbial inoculant Bacillus subtilis 8–32, in appropriate concentrations, could be applied to promote root and shoot growth and improve the seedling quality of the lacebark pine during cultivation.

Swine wastewater compost and arbuscular mycorrhizal fungi in the growth and accumulation of copper in Eucalyptus grandis

The objective of this work was to determine the influence of arbuscular mycorrhizal fungi (AMF) and swine wastewater compost (SWC) on the growth and accumulation of copper in Eucalyptus grandis cultivated in soil contaminated with copper. The experiment was conducted in a greenhouse for 120 days, using a completely randomized experimental design in a factorial arrangement (2 × 3), with and without 40% SWC (v: v) and three inoculation treatments with AMF (without fungus, Gigaspora margarita and Aucalospora colombiana), totaling six treatments with eight replicates in soil previously contaminated with 400 mg kg−1 of copper. The height, stem diameter, root and shoot dry mass, and root and shoot content, Dickson quality index and translocation, relative efficiency of treatments for height of the seedlings and mycorrhizal colonization were evaluated. The addition of SWC and Gigaspora margarita increased morphological parameters and quality of seedlings in contaminated soil.