• Korean Journal of Soil Science and Fertilizer
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• v.49 no.4
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• pp.318-326
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• 2016

Two phosphate solubilizing bacteria, Pantoea rodasii PSB-11and Enterobacter aerogenes PSB-12, were isolated from button mushroom compost and employed to assess their synergistic effect in liquid medium and on growth of green gram plants by single and co-inoculation of the strains. Co-inoculation of two strains was found to release the highest content of soluble phosphorus ($521{\mu}g\;ml^{-1}$) into the medium, followed by single inoculation of Pantoea strain ($485{\mu}g\;ml^{-1}$) and Enterobacter strain ($470{\mu}g\;ml^{-1}$). However, there was no significant difference between single inoculation of bacterial strain and co-inoculation of two bacterial strains in terms of phosphorous release. The highest pH reduction, organic acid production and glucose consumption was observed in the E. aerogenes PSB-12 single inoculated culture medium rather than those of co-inoculation. According to the plant growth promotion bioassay, co-inoculated mung bean seedlings recorded 10.6% and 10.7% higher shoot and root growth respectively compared to the control. Therefore, in concluding, co-inoculation of the strains P. rodasii and E. aerogenes displayed better performance in stimulating plant growth than inoculation of each strain alone. However, being short assessment period of the present study, we recommend in engaging further works under field conditions in order to test the suitability of the strains to be used as bio-inoculants.

• Korean Journal of Agricultural Science
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• v.43 no.3
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• pp.401-414
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• 2016

The synergistic effect on phosphate solubilization of single- and co-inoculation of two phosphate solubilizing bacteria, Burkholderia anthina PSB-15 and Enterobacter aerogenes PSB-16, was assessed in liquid medium and green gram plants. Co-inoculation of two strains was found to release the highest content of soluble phosphorus ($519{\mu}g\;mL^{-1}$) into the medium, followed by single inoculation of Burkholderia strain ($492{\mu}g\;mL^{-1}$) and Enterobacter strain ($483{\mu}g\;mL^{-1}$). However, there was no significant difference between single inoculation of bacterial strain and co-inoculation of two bacterial strains in terms of phosphorous release. The highest pH reduction, organic acid production, and glucose consumption were observed in the culture medium co-inoculated with PSB-15 and PSB-16 strains rather than that of single inoculation. Based on the plant growth promotion bioassay, co-inoculated mung bean seedlings recorded 9% and 8% higher shoot and root growth, respectively, compared to the control. Therefore, in conclusion, co-inoculation of the strains B. anthina and E. aerogenes displayed better performance in stimulating plant growth than inoculation of each strain alone. However, considering the short assessment period of the present study, we recommend engaging in further work under field conditions in order to test the suitability of these strains as bio-inoculants.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.2
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• pp.117-121
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• 2013

Single or co-inoculation of phosphate solubilizing bacterial and fungal strains (Burkholderia anthina and Aspergillus awamori respectively) was performed separately to assess their synergistic and antagonistic interactions and the potential to be used as bio-inoculants. Co-inoculation was found to release the highest content of soluble phosphorus (1253 ${\mu}g\;ml^{-1}$) into the medium, followed by single inoculation of fungal strain (1214 ${\mu}g\;ml^{-1}$) and bacterial strain (997 ${\mu}g\;ml^{-1}$). However, there was no significant difference between single inoculation of fungal strain and co-inoculation of fungal and bacterial strain in terms of the phosphorous release. The highest pH reduction, organic acid production and glucose consumption were observed in the sole A. awamori inoculated culture medium. According to the plant growth promotion bioassays, co-inoculation of the microbial strains resulted in 21% and 43% higher shoot and root growth of the mung bean seedlings respectively as compared to the respective controls. Therefore, co-inoculation of B. anthina and A. awamori showed better performance in stimulating plant growth than that in inoculation of each strain alone. However, assessment period of the present study being short, we recommend in engaging further experimentation under field conditions in order to test the suitability of the strains to be used as bio-inoculants.

• The Plant Pathology Journal
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• v.38 no.3
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• pp.212-219
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• 2022

Fusarium root rot caused by the soil-borne fungus Fusarium solani is one of the most important fungal diseases of cassava in Thailand, resulting in high yield losses of more than 80%. This study aimed to investigate if the exogenous application of salicylic acid formulations (Zacha) can induce resistance in cassava against Fusarium root rot and observe the biochemical changes in induced cassava leaf tissues through synchrotron radiation based on Fourier-transform infrared (SR-FTIR) microspectroscopy. We demonstrated that the application of Zacha11 prototype formulations could induce resistance against Fusarium root rot in cassava. The in vitro experimental results showed that Zacha11 prototype formulations inhibited the growth of F. solani at approximately 34.83%. Furthermore, a significant reduction in the disease severity of Fusarium root rot disease at 60 days after challenge inoculation was observed in cassava plants treated with Zacha11 at a concentration of 500 ppm (9.0%). Population densities of F. solani were determined at 7 days after inoculation. Treatment of the Zacha11 at a concentration of 500 ppm resulted in reduced populations compared with the distilled water control and differences among treatment means at each assay date. Moreover, the SR-FTIR spectral changes of Zacha11-treated epidermal tissues of leaves had higher integral areas of lipids, lignins, and pectins (1,770-1,700/cm), amide I (1,700-1,600/cm), amide II (1,600-1,500/cm), hemicellulose, lignin (1,300-1,200/cm), and cellulose (1,155/cm). Therefore, alteration in defensive carbohydrates, lipids, and proteins contributed to generate barriers against Fusarium invasion in cassava roots, leading to lower the root rot disease severity.

• The Plant Pathology Journal
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• v.38 no.4
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• pp.261-271
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• 2022

Root-knot nematodes are the most important plant-parasitic nematodes worldwide. Many efforts have been made to find non-chemical, risk-free, and environmentally friendly methods for nematode control. In this study, the effects of compost and vermicompost of arugula (Eruca sativa) on Meloidogyne javanica were investigated in three glasshouse experiments. In addition, the expression of the defense-related genes nonexpressor of pathogenesis-related 1 (NPR1) and lipoxygenase 1 (LOX1) was detected in tomato plants treated with vermicompost of arugula at 0, 2, 7, and 14 days after nematode inoculation. The result showed that the vermicompost of arugula significantly reduced the reproduction factor of the nematode by 54.4% to 70.5% in the three experiments and increased the dry weight of shoots of infected tomato plants. Gene expression analysis showed that LOX1 expression increased on the second and seventh day after nematode inoculation, while NPR1 expression decreased. The vermicompost of arugula showed stronger nematode inhibitory potential than the vermicompost of animal manure. The vermicompost of arugula is superior to arugula compost in suppressing the activity of M. javaniva and reducing its impact. It manipulates the expression of resistance genes and could induce systemic resistance against root-knot nematodes.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.4
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• pp.329-336
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• 1989

A series of green house experiment was conducted to find but the effect of fertilizer application and inoculation of rhizobium on the changes of amide-N, ureide-N and $NH_4-N$ concentration in stem and root exudates of soybean plant growth. The results obtained were summarized as follows ; 1. Five strains of indigenous Rhizobium japonicum-nitrogen fixing activity($C_2H_2$-reducing activity) was more than 6.4 to 20.1 nmole/hr/tube-were identified from 37 soil samples in 22 areas of farmers field throughout country. 2. These identified 5 strains of rhizobium were obtained high nitrate reductase but low ammonium and nitrite oxidase activities. Among 5 strains of rhizobium the Rhizobium japonicum RjK-134 was applied for this green house experiment. 3. Dry matter yield was increased by the combination of inoculation of Rhizobium japonicum RjK-134 with no fertilizer and without nitrogen fertilizer application. However, dry matter yield was decreased with application of N and NPK with inoculation of rhizobium. 4. The concentrations of amide-N and ureide-N were increased in xylem sap than that of root exudate and higher concentration was obtained ar 30 days after planting than flowering stage (45 days after planting). 5. The combination of NPK application with inoculation of Rhrizobium japonicum RjK-134 enhanced the increase of amide-N and ureide-N concentration in xylem sap and root exudate. 6. High ammonium-N concentration in xylem sap and root exudate were obtained in combination with without-fertilizer under no inoculation of rhizobium and N and NPK application with inoculation of rhizobium.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.4
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• pp.245-252
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• 1995

To select a carrier as Rhizobiwn inoculants for alfalfa, severeal Rhizobium inoculants were produced by adding or not sub-materials($CaCO_3$ and sucrose) to main materials(organic or inorganic materials). The root nodule bacteria, Rhizobium meliloti 1061 distributed from KAIST, and Vemal alfalfa was used in this experiment. The Rhizobium populations and inoculation effects of the Rhizobium inoculants produced in several materials were scrutinized at laboratory and greenhouse in Livestock Experiment Station, RDA from 1993 to 1994. Moisture contents of the caniers were varied from 32 to 50% on dry weight basis according to material characteristics and the pH ranges of these were varied from pH 4.56 to 10.06 according to raw material characteristics and preparations. Initial Rhizobium numbers of the carriers were higher in organic material-inoculants than in inorganic, and among the inoculants, the inoculant made of Bentonite+Vermiculite(l:3 w/w) was excellent because of high rhizobium population($7.8~8.3\times10^8/g$ inoculant) and high rhizobium reappearance of inoculant in severed different production time. The root nodules of the alfalfa inoculated with different inoculants were fast formed in the fermented sawdust with cattle dung (FSC) inoculant, and bentonite(B)+vermiculite(V) than others. Plant length of alfalfa was differentiated on 15 days after inoculation but was not nearly different between higher inoculants than rhizobium number $10^7/g$ inoculant. Total dry matter of alfalfa was yielded by 20.65, 20.34mg per pot in FSC + sucrose 0.5% and B + V + sucrose 1% inoculants respectively that were higher inoculation effect by 17 times compared with non-inoculation, 1.2 mg per pot.

• Korean Journal of Environmental Agriculture
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• v.30 no.2
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• pp.223-228
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• 2011

BACKGROUND: Rhizosphere bacteria may improve plant growth and productivity both by supply nutrients and hormonal stimulation. Although many experiments have shown improvements in plant growth with inoculation of bacterial cultures to the rhizosphere, the main obstacle in the applications of plant growth promoting rhizobacteria in a large scale is the inconsistency of the results. We tested the growth promoting effects of Azospirillum and Methylobacterium strains on red pepper plant. METHODS AND RESULTS: Red pepper seedlings were grown for 25 days in a growth media inoculated with A. brasilense CW903 or M. oryzae CBMB20. The seedlings were transplanted and grown for 45 days in pots with soil in a greenhouse, at half the recommended level of fertilizer. Bacterial culture, $4.0{\times}10^9$ for A. brasilense CW903 and $5.8{\times}10^8$ CFU for M. oryzae CBMB20, was applied in root zone soil periodically every 10 days during the experiment. Inoculation of M. oryzae CBMB20 significantly increased the red pepper plant growth in terms of leaf number, height and mass of shoot, or root mass compared to uninoculated control plants. Although beneficial effects of A. brasilense on plant growth of many crops were observed, the growthpromoting effect of A. brasilense CW903 on red pepper plant was not found in this study. CONCLUSION(s): The factors responsible for the irregularities in plant growth promoting of rhizobacteria are difficult to elucidate. Extensive inoculation experiments in the greenhouse and in the field should enable us to define the factors critical to obtain successful application of plant growth promoting rhizobacteria.

• Journal of Microbiology and Biotechnology
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• v.17 no.8
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• pp.1300-1307
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• 2007

This study assessed the possible role of different traits in selected plant growth-promoting rhizobacteria (PGPR) for improving wheat growth and yield under natural conditions. Rhizobacteria exhibiting 1-aminocyclopropane-1-carboxylate (ACC)-deaminase activity were isolated and screened for their growth-promoting activity in wheat under axenic conditions. Five isolates belonging to Pseudomonas and one Burkholderia caryophylli isolate that showed promising performances under axenic conditions were selected and characterized for in vitro ACC-deaminase activity, chitinase activity, auxin production, P solubilization, and root colonization. These isolates were then used as inocula for wheat cultivated under natural conditions in pot and/or field trials. Significant increases in root elongation, root weight, tillers per pot, 1,000-grain weight, and grain and straw yields were observed in response to inoculation with PGPR in the pot trials. Inoculation with these PGPR was also effective under field conditions and increased the wheat growth and yield significantly. However, the efficacy of the strains was inconsistent under the axenic, pot, and field conditions. Pseudomonas fluorescens ($ACC_{50}$), which exhibited a relatively high in vitro ACC-deaminase activity, chitinase activity, auxin production, and P solubilization and more intensive root colonization, was the most efficient isolate under the field conditions. Therefore, these results demonstrated that ACC-deaminase activity is an efficient parameter for the selection of promising PGPR under axenic conditions. However, additional traits of PGPR, including auxin production, chitinase activity, P solubilization, and root colonization, are also important for selecting PGPR as biofertilizers.

• Plant Disease and Agriculture
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• v.5 no.2
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• pp.84-89
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• 1999

Development of root galls of clubroot disease on Chinese cabbage seedlings was first observed 17days after inoculation of Plasmodiophora brassicae at $25^{\circ}C$ 4-11days earlier than at 5, 20, 3$0^{\circ}C$ and 35$^{\circ}C$. Subsequent enlargement of root galls was also fastest at $25^{\circ}C$ and 2$0^{\circ}C$ but delayed at 15$^{\circ}C$ and 3$0^{\circ}C$ or above. Chinese cabbage seedlings with root gall formation showed reduction in number of leaves above ground fresh weight and amount of root hairs but increase in root weight, Root galls development was highest at soil moisture level of 80% of maximum soil moisture capacity than at 60% and 100%. Optimum soil pH for root gall development was pH 6 although root galls were formed at a range of pH 5 to 8. Period of light illumination also affected root gall development with the greatest gall development at 12hr/12hr in light/dark period and the least at 8hr/16hr. Site of root gall formation and gall shape did not differ greatly among treatments of temperature soil moisture pH and light experiments.