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Plant associated endospore forming bacteria from amaranthus as growth promoters and biocontrol agents against rhizoctonia leaf blight

By: Yashwasini M S.
Contributor(s): Anith, K N (Guide).
Material type: materialTypeLabelBookPublisher: Vellayani Department of Agricultural Microbiology, College of Agriculture 2020Description: 148p.Subject(s): Plant associated endospore forming | Growth promoters and biocontrol agentsDDC classification: 660.62 Online resources: Click here to access online Dissertation note: MSc Abstract: ABSTRACT The study entitled “Plant associated endospore forming bacteria from amaranthus as growth promoters and biocontrol agents against Rhizoctonia leaf blight”, was conducted during 2018-2020, in the Department of Agricultural Microbiology, College of Agriculture, Vellayani, Thiruvananthapuram, with the objective of isolation and characterization of endospore forming bacteria from endorhizosphere and phyllosphere of Amaranthus and evaluate their effect on growth promotion and disease suppression. Endospore forming bacteria from endorhizosphere and phyllosphere were isolated from healthy roots and leaves of red amaranthus variety Arun, green amaranthus var. CO1 and wild relative (Amaranthus viridis) respectively by enrichment method on NA medium. A total of eight endospore forming bacterial isolates were obtained each from endorhizosphere and phyllosphere of the variety Arun, variety CO-1 and wild relative (Amaranthus viridis). All the isolates were identified as Bacillus spp. based on morphological, biochemical and molecular characterization. These isolates designated as AR1, AR2, AR3, GR1, GR2, GR3, WR1, WR2, AL1, AL2, AL3, GL1, GL2, GL3, WL1 and WL2 were identified as Bacillus sp., Bacillus siamensis, Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus amyloliquefaciens, Bacillus amyloliquefaciens, Bacillus sp., Bacillus amyloliquefaciens, Bacillus sp., Bacillus subtilis, Bacillus sp., Bacillus amyloliquefaciens, Bacillus sp., Bacillus sp., Bacillus subtilis and Bacillus amyloliquefaciens respectively based on 16S rRNA sequence. Indole Acetic Acid production by the different endospore forming endorhizosphere bacterial isolates ranged from 4.09 to 9.73 μg mL-1 of culture filtrate. The isolate AR3 produced the maximum IAA of 9.73 μg mL-1 of culture filtrate. In roll towel assay significant increase in germination percentage, seedling shoot length, root length and seedling vigour index compared to control was observed when seeds were treated with the endospore forming endorhizosphere bacterial isolates. Isolate WR1 showed the maximum germination (43.33%) whereas control recorded a germination of 30%. Isolate WR1 showed maximum seedling vigour index (223.66) compared to the control (136.53). A portray experiment was also conducted to study the influence of endospore forming endorhizosphere bacterial isolates on plant growth parameters of amaranthus in the nursery stage. Highest root length was observed in the seedlings treated with isolate GR1 (4.76 cm) whereas the control recorded 3.91 cm. Shoot length was the maximum in seeds treated with WR1 (6.34 cm) whereas control recorded a shoot length of 5.59 cm. Maximum germination percentage of 100 was obtained in seeds treated with the isolate WR2. Significant influence of the bacterial isolates on seedling vigour index was observed wherein the isolate WR2 recorded maximum of 884.50. Highest root fresh weight was recorded in the plants treated with isolate GR1 (8.12 mg/plant) and the lowest root fresh weight of 3.56 mg/plant was recorded in control plants. It was found that the highest root dry weight was found in plants treated with isolate WR1 (2.99 mg/plant) as against the control (2.46 mg/plant). Dual culture plate assay was carried out on Potato Dextrose Agar medium to check the ability of endospore forming phyllopshere bacterial isolates to inhibit Rhizoctonia solani causing foliar blight disease. All the isolates inhibited the mycelial growth of Rhizoctonia solani, of which GL3 and GL1 exhibited the maximum and minimum zone of inhibition (ZOI) of 8.73 and 1.00 mm respectively. All the endospore forming phyllopshere bacterial isolates tested for their indirect antagonism inhibited Rhizoctonia solani mycelial growth, of which isolate GL3 showed the maximum ZOI of 2.88 mm and the minimum was recorded by the isolate GL1 (0.50 mm). In detached leaf assay, significant difference was noticed in the lesion size appeared on the detached leaves treated with endospore forming phyllosphere bacterial isolates and water (control) on 3rd and 4th day after pathogen inoculation. Control exhibited maximum lesion area of 3.49 and 12.23 cm2 and the minimum lesion area of 0.42 and 3.11 cm2 was developed on the leaves treated with isolate WL2 on 3rd and 4th day after pathogen inoculation respectively. Based on in vitro studies on plant growth promotion and antagonistic activity against R. solani the endospore forming endorhizosphere bacterial isolates AR1, AR2, GR1, GR2, WR1 and WR2 and endospore forming phyllosphere bacterial isolates - AL1, AL3, GL2, GL3, WL1 and WL2 were selected for further pot culture study. A pot culture experiment was conducted to evaluate the efficacy of selected endospore forming endorhizosphere bacteria for their plant growth promoting activity in Amaranthus (var. Arun). Endospore forming endorhizosphere bacteria inoculated plants showed significant increase in biometric parameters such as number of leaves, number of branches, plant height and dry matter production compared to control. Plants treated with Bacillus amyloliquefaciens GR1 exhibited the maximum shoot fresh weight of 54.30 g/plant, whereas the control plants showed the minimum of 40.24 g/plant. Shoot dry matter production was maximum with plants treated with the isolate AR2 (6.74 g/plant) and the control plants recorded 4.76 g/plant. Bacillus amyloliquefaciens GR1 treated plants produced maximum root fresh weight of 13.64 g/plant, whereas the control plants had root fresh weight of 9.88 g/plant. Maximum root dry weight was exhibited by plants treated with Bacillus amyloliquefaciens GR1 (1.98 g/plant), lowest was produced by control plants with 1.37 g/plant. Suppression of Rhizoctonia leaf blight in the variety Arun treated with selected endospore forming phyllosphere bacterial isolates was studied by challenge inoculation with the pathogen on intact leaves. The bacterial suspension containing bacterial cells of concentration 107 cfu ml-1 was sprayed on to the intact leaves of plants one week prior to pathogen inoculation. On 3rd day after pathogen inoculation, plants treated with Bacillus sp GL3 showed the minimum percent disease index of 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen cosuppression over the pathogen control, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the Bacillus sp AL3 with with 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. No symptom development was observed in absolute control. On 5th day after pathogen inoculation, Bacillus sp AL3 treated plants showed the minimum percent disease index of 18 .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the pathogen inoculated control. pathogen inoculated control. pathogen inoculated control. pathogen inoculated control. pathogen inoculated control. pathogen inoculated control. The present study revealed that seed bacterization of amaranthus plants with endospore forming endorhizosphere and foliar spray of phyllosphere bacterial isolates improved plant growth and suppressed Rhizoctonia solani leaf blight incidence respectively and helps in better establishment of plants. Bacillus amyloliquefaciens GR1 and Bacillus sp AL3 were selected as the best isolates for plant growth promotion and disease suppression respectively.
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Reference Book 660.62 YAS/PL PG (Browse shelf) Not For Loan 174912

MSc

ABSTRACT
The study entitled “Plant associated endospore forming bacteria from amaranthus as growth promoters and biocontrol agents against Rhizoctonia leaf blight”, was conducted during 2018-2020, in the Department of Agricultural Microbiology, College of Agriculture, Vellayani, Thiruvananthapuram, with the objective of isolation and characterization of endospore forming bacteria from endorhizosphere and phyllosphere of Amaranthus and evaluate their effect on growth promotion and disease suppression.
Endospore forming bacteria from endorhizosphere and phyllosphere were isolated from healthy roots and leaves of red amaranthus variety Arun, green amaranthus var. CO1 and wild relative (Amaranthus viridis) respectively by enrichment method on NA medium. A total of eight endospore forming bacterial isolates were obtained each from endorhizosphere and phyllosphere of the variety Arun, variety CO-1 and wild relative (Amaranthus viridis). All the isolates were identified as Bacillus spp. based on morphological, biochemical and molecular characterization. These isolates designated as AR1, AR2, AR3, GR1, GR2, GR3, WR1, WR2, AL1, AL2, AL3, GL1, GL2, GL3, WL1 and WL2 were identified as Bacillus sp., Bacillus siamensis, Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus amyloliquefaciens, Bacillus amyloliquefaciens, Bacillus sp., Bacillus amyloliquefaciens, Bacillus sp., Bacillus subtilis, Bacillus sp., Bacillus amyloliquefaciens, Bacillus sp., Bacillus sp., Bacillus subtilis and Bacillus amyloliquefaciens respectively based on 16S rRNA sequence.
Indole Acetic Acid production by the different endospore forming endorhizosphere bacterial isolates ranged from 4.09 to 9.73 μg mL-1 of culture filtrate. The isolate AR3 produced the maximum IAA of 9.73 μg mL-1 of culture filtrate. In roll towel assay significant increase in germination percentage, seedling shoot length, root length and seedling vigour index compared to control was observed when seeds were treated with the endospore forming endorhizosphere bacterial isolates. Isolate WR1 showed the maximum germination (43.33%) whereas control recorded a germination of 30%. Isolate WR1 showed maximum seedling vigour index (223.66) compared to the control (136.53). A portray experiment was also conducted to study the influence of endospore forming endorhizosphere bacterial isolates on plant growth parameters of amaranthus in the nursery stage. Highest root length was observed in the seedlings treated with isolate GR1 (4.76 cm) whereas the control recorded 3.91 cm. Shoot length was the maximum in seeds treated with WR1 (6.34 cm) whereas control recorded a shoot length of 5.59 cm. Maximum germination percentage of 100 was obtained in seeds treated with the isolate WR2. Significant influence of the bacterial isolates on seedling vigour index was observed wherein the isolate WR2 recorded maximum of 884.50. Highest root fresh weight was recorded in the plants treated with isolate GR1 (8.12 mg/plant) and the lowest root fresh weight of 3.56 mg/plant was recorded in control plants. It was found that the highest root dry weight was found in plants treated with isolate WR1 (2.99 mg/plant) as against the control (2.46 mg/plant).
Dual culture plate assay was carried out on Potato Dextrose Agar medium to check the ability of endospore forming phyllopshere bacterial isolates to inhibit Rhizoctonia solani causing foliar blight disease. All the isolates inhibited the mycelial growth of Rhizoctonia solani, of which GL3 and GL1 exhibited the maximum and minimum zone of inhibition (ZOI) of 8.73 and 1.00 mm respectively. All the endospore forming phyllopshere bacterial isolates tested for their indirect antagonism inhibited Rhizoctonia solani mycelial growth, of which isolate GL3 showed the maximum ZOI of 2.88 mm and the minimum was recorded by the isolate GL1 (0.50 mm). In detached leaf assay, significant difference was noticed in the lesion size appeared on the detached leaves treated with endospore forming phyllosphere bacterial isolates and water (control) on 3rd and 4th day after pathogen inoculation. Control exhibited maximum lesion area of 3.49 and 12.23 cm2 and the minimum lesion area of 0.42 and 3.11 cm2 was developed on the leaves treated with isolate WL2 on 3rd and 4th day after pathogen inoculation respectively. Based on in vitro studies on plant growth promotion and antagonistic activity against R. solani the endospore forming endorhizosphere bacterial isolates AR1, AR2, GR1, GR2, WR1 and WR2 and endospore forming phyllosphere bacterial isolates - AL1, AL3, GL2, GL3, WL1 and WL2 were selected for further pot culture study.
A pot culture experiment was conducted to evaluate the efficacy of selected endospore forming endorhizosphere bacteria for their plant growth promoting activity in Amaranthus (var. Arun). Endospore forming endorhizosphere bacteria inoculated plants showed significant increase in biometric parameters such as number of leaves, number of branches, plant height and dry matter production compared to control. Plants treated with Bacillus amyloliquefaciens GR1 exhibited the maximum shoot fresh weight of 54.30 g/plant, whereas the control plants showed the minimum of 40.24 g/plant. Shoot dry matter production was maximum with plants treated with the isolate AR2 (6.74 g/plant) and the control plants recorded 4.76 g/plant. Bacillus amyloliquefaciens GR1 treated plants produced maximum root fresh weight of 13.64 g/plant, whereas the control plants had root fresh weight of 9.88 g/plant. Maximum root dry weight was exhibited by plants treated with Bacillus amyloliquefaciens GR1 (1.98 g/plant), lowest was produced by control plants with 1.37 g/plant.
Suppression of Rhizoctonia leaf blight in the variety Arun treated with selected endospore forming phyllosphere bacterial isolates was studied by challenge inoculation with the pathogen on intact leaves. The bacterial suspension containing bacterial cells of concentration 107 cfu ml-1 was sprayed on to the intact leaves of plants one week prior to pathogen inoculation. On 3rd day after pathogen inoculation, plants treated with Bacillus sp GL3 showed the minimum percent disease index of 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen cosuppression over the pathogen control, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the Bacillus sp AL3 with with 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. No symptom development was observed in absolute control. On 5th day after pathogen inoculation, Bacillus sp AL3 treated plants showed the minimum percent disease index of 18 .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the pathogen inoculated control. pathogen inoculated control. pathogen inoculated control. pathogen inoculated control. pathogen inoculated control. pathogen inoculated control. The present study revealed that seed bacterization of amaranthus plants with endospore forming endorhizosphere and foliar spray of phyllosphere bacterial isolates improved plant growth and suppressed Rhizoctonia solani leaf blight incidence respectively and helps in better establishment of plants. Bacillus amyloliquefaciens GR1 and Bacillus sp AL3 were selected as the best isolates for plant growth promotion and disease suppression respectively.

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