Evaluation of biofilm based microbial antagonists for the management of soil borne diseases and growth promotion in cowpea (Vigna unguiculata L. Walp)
| dc.contributor.advisor | Surendra Gopal, K | |
| dc.contributor.author | Vinay Kumar, B | |
| dc.contributor.author | KAU | |
| dc.date.accessioned | 2020-03-12T06:46:46Z | |
| dc.date.available | 2020-03-12T06:46:46Z | |
| dc.date.issued | 2018 | |
| dc.description | PG | en_US |
| dc.description.abstract | The biocontrol agents play an important role in the plant disease management and growth promotion. They are eco-friendly and low cost agricultural inputs. One of the major constraints in the use of biocontrol agents, is the survivability of inoculated cultures till the end of the crop period. So, there is a need to enhance the survivability of the biocontrol agents for the management of soil borne pathogens and growth promotion. Trichoderma and Bacillus sp. are two well-known biocontrol agents for plant disease management and growth promotion. Cowpea is one of the most popular, protein rich legume crop of Kerala. One of the major constraints in the cowpea production is the diseases like collar- rot (Rhizoctonia solani) and root rot (Pythium aphanidermatum) which have become a serious threat. Since, no studies have been conducted in Kerala on the biofilm based inoculants, an attempt was made to increase the survivability of Trichoderma and Bacillus through biofilm based inoculants for the management of two major soil borne diseases and growth promotion in cowpea. Rhizosphere soil samples were collected from ten different cowpea growing areas of Thrissur district. The maximum population of Trichoderma sp. (4.8 × 103 cfu g-1) and Bacillus sp. (4.48 × 105 cfu g-1) were recorded in Chellakara and Mala, respectively. A total of nine Trichoderma sp. and five Bacillus sp. were obtained. They were screened for plant growth promoting and antagonistic activities. Among Trichoderma sp., maximum IAA production (24.03 μg ml-1) was recorded by TCK- 2 (Chalakudy) followed by TML (Mala) (14.77 μg ml-1). TML (Mala) isolate was the most efficient P solubilizer (147.2 μg/ml). Among Bacillus sp., maximum IAA production (6.20 μg ml-1) and maximum P solubilization (151.3 μg ml-1) were recorded by BCH (Chellakara) isolate. Among Trichoderma sp., TCH-1 (Chellakara) and TMT (Mttathur) were positive for HCN production and TCH-1, TMT, TMS, TPZ and TCK-1 were positive for ammonia production. Among Bacillus sp., BCH (Chellakara) and BMT (Mattathur) were positive for HCN production and all five isolates (BCH, BML, BMS, BPN and BMT) were positive for ammonia production. Both Trichoderma sp. and Bacillus sp. were screened in vitro for their antagonistic activity against Rhizoctonia solani and Pythium aphanidermatum. Among Trichoderma sp., TCH-1 (Chellakara) isolate recorded maximum inhibition (51.1%) against Rhizoctonia solani and Pythium aphanidermatum (57.7%). Bacillus sp. isolates were screened for biofilm production and highest biofilm production was recorded by BCH (Chellakara) (0.060) followed by BPN (Pazhayanur) (0.058) isolates. Based on the PGPR traits, per cent inhibition and biofilm production under in vitro, three most promising Trichoderma sp. (TCH, TMT, TPZ) and Bacillus sp. (BCH, BPN, BML) were subjected for mutual compatibility studies. All the selected Trichoderma sp. and Bacillus sp. were mutually compatible with each other. The isolates of TCH (Chellakara) + BCH (Chellakara), TPZ (Pazhayanur) + BPN (Pazhayanur) and TMT (Mattathur) + BML (Mala) were selected for the biofilm based inoculant production. Among the different carrier materials for biofilm based inoculant production talc powder was the most promising carrier material due to highest population of isolates at 90 DAI. Biofilm based inoculants were evaluated under pot culture for the management of collar rot (Rhizoctonia solani) and root rot (Pythium aphanidermatum) in cowpea under two separate experiments. Based on the biometric parameters, collar rot and root rot disease management and yield parameters, biofilm based formulation of TCH (Chellakara)+BCH (Chellakara) (T2) was the most promising treatment for the management of collar rot disease and growth promotion in cowpea, which was on par with the PGPR Mix- II (T9). Population of inoculated Trichoderma sp., Bacillus sp. and Rhizobium sp. indicated declining trend till the final harvest of the crop. The population decreased from 108 cfu ml-1 to 104 cfu ml-1. However, biofilm based inoculant showed highest population of Trichoderma sp. and Bacillus sp. at the time of harvest. The three best promising Bacillus sp. isolates were identified through 16S rRNA sequencing and identified BCH isolate as Bacillus subtilis, BPN as Bacillus velezensis and BML as Bacillus megaterium. | en_US |
| dc.identifier.uri | http://krishikosh.egranth.ac.in/handle/1/5810145225 | |
| dc.keywords | Cowpea, Vigna unguiculata, Collar rot, Anthracnose, Bacillus megaterium, Trichoderma sp., Bacillus subtilis, Rhizoctonia solani, Pythium aphanidermatum, Rhizosphere soil | en_US |
| dc.language.iso | en | en_US |
| dc.pages | 98 | en_US |
| dc.publisher | Department of Agricultural Microbiology, College of Horticulture, Vellanikkara | en_US |
| dc.sub | Agricultural Microbiology | en_US |
| dc.subject | null | en_US |
| dc.theme | Evaluation of biofilm based microbial antagonists | en_US |
| dc.these.type | M.Sc | en_US |
| dc.title | Evaluation of biofilm based microbial antagonists for the management of soil borne diseases and growth promotion in cowpea (Vigna unguiculata L. Walp) | en_US |
| dc.type | Thesis | en_US |