Phyllosphere microorganisms for the management of anthracnose disease of Cowpea (Vigna unguiculata (L.) Walp.)
| dc.contributor.advisor | Sainamole Kurian, P | |
| dc.contributor.author | Anupama P R. | |
| dc.contributor.author | KAU | |
| dc.date.accessioned | 2024-04-29T11:06:07Z | |
| dc.date.available | 2024-04-29T11:06:07Z | |
| dc.date.issued | 2022-07-08 | |
| dc.description.abstract | Microorganisms associated with aerial parts of plants such as stems (cauloshere), phylloplane (leaves), anthosphere (flowers) and carposphere (fruits) which are collectively known as phyllosphere. Phyllosphere microbes includes bacteria, filamentous fungi and yeasts. They offer natural biological control of diseases affecting aerial plant parts. Being better adapted to the phyllosphere niche, they are potential biocontrol agents which are under exploited in agriculture which allow them to adapt to the phyllosphere environment and inhibit the growth of microbial pathogens, thus sustaining plant health. Hence, microbial biocontrolbyphyllosphere microorganisms is a fast growing field of research. Considering the importance of the potential of phyllosphere antagonists, the research project entitled “Phyllosphere microorganisms for the management of anthracnose disease of cowpea (Vigna unguiculata (L.) Walp.).” was carried out. Phyllosphere microbiome enhance plant tolerance to withstand biotic and abiotic stress conditions in the current facet of climate change. A purposive sampling survey was conducted in 21 locations of Kerala where cowpea and/or yard long bean are grown as a vegetable crop. The survey covered six districts namely, Thrissur, Palakkad, Malappuram, Kozhikode, Kannur and Kasaragod and five agro ecological units. Fungi associated with anthracnose symptoms and phylloshere microrganisms associated with healthy and symptomless plants from the fields were isolated. On pathogenicity test, six fungi were confirmed as pathogens and they were identified as Colletotrichum Siamense, three isolates of Colletotrichum sp., Ectophoma multirostrata and Curvularia verruculosa based on cultural, morphological and molecular characterization.C. siamense and Ectophoma multirostrata infecting cowpea is the first report in the world. Similarly, first report of Curvularia verruculosa infecting cowpea and producing anthracnose symptoms from India. Enumeration of phyllosphere microorganisms on cowpea grown at different locations showed that population of fungi distributed on all plant parts and more abundant on flowers. Likewise, bacteria are more abundant on cowpea flowers, and fluorescent pseudomonads and yeasts are more abundantly seen on cowpea pods. Based on colony characters, a total of 183 different isolates of phyllosphere microbes were made into pure cultures and were screened for antagonism towards C. siamense. Forty one isolates expressed antagonism in varying degrees which were again subjected to dual culture screening in vitro. Five promising anatgonists were selected based on per cent inhibition of mycelium of the pathogen on PDA. The five were identified as Trichoderma longibrachiatum, Trichoderma asperellem, Bacillus amyloliquefaciens, Bacillus velezensis and Candida tropicalis based on cultural, morphological and molecular characterization. Cell free culture filtrates of promising phyllosphere antagonists showed maximum growth inhitbion of C. siamense ranging from 86 per cent for Candida tropicalis to 100 per cent for Trichoderma longibrachiatum and Trichoderma asperellem In order to study the induction of systemic resistance in cowpea by phyllosphere antagonists, a pot culture experiment was conducted and the results showed that all the antagonists accelerate the production of defence related enzymes such as peroxidase, polyphenol oxidase and phenylalanine ammonia lyase when challenge inoculated with the pathogen. Bacillus amyloliquefaciens induced higher activity of peroxidase (1.2 min-1g-1 fresh tissue over control), similarly polyphenol oxidase by Candida tropicalis (0.5min-1g-1 fresh tissue over control) and phenylalanine alanine by Trichoderma asperellem (0.8 μmol of transcinnamic acid formed g-1 fresh tissue over the control). To test the biocontrol efficacy and plant growth promotion of phyllosphere antagonists against C. siamense causing cowpea anthracnose, a field experiment was conducted. The semi trailing cowpea variety ‘Anashwara’ was used in the experiment. The treatments included conventional biocontrol agents such as Trichoderma sp. (KAU) and Pseudomonas fluorescens (KAU) and chemical check with hexaconazole (systemic), mancozeb (contact) and carbendazim + mancozeb (systemic +contact) and a control without treatments were also included along with five phyllsophere antagonists such as T. longibrachiatum, T. asperellem, B. amyloliquefaciens, B. velezensis and C. tropicalis. All the treatments were given as seed treatment, and foliar spray. Higher vigour index of seedlings was recorded in the treatment with Bacillus amyloliquefaciens (1408). Biometric observations such as plant height, number of main branches, number of pods per plant, number of seeds per pod, fresh weight of pods, pod length, days to first harvest, days to last harvest and total yieldand per cent disease incidence and severity were recorded at regular interval. Results of the field experiment indicated significant reduction in disease incidence and severity effected by phyllosphere antagonists such as T. asperellem, B. amyloliquefaciens, B. velezensis, C. tropicalis, Trcihoderma sp. (KAU), Pseudomonas fluorescens, hexaconazole, mancozeb and carbendazim + Mancozeb. In terms of yield all the five antagonists along with Trichoderma sp. (KAU) recorded significant yield increase in cowpea compared to other treatments. The bacteria, B. amyloliquefaciens has gained more attention and an emerging evidence has identified its health beneficial effects as probiotics, hence farmers can safely use this as a biocontrol agent. Focusing on efficient and safer (non pathogenic nature), the phyllosphere antagonists such as T. asperellem and B. amyloliquefaciens are selected as the best among all the treatments. So, it can be concluded that out of the eleven treatments, T. asperellem and B. amyloliquefaciens could promote the growth of the plants and reduce the disease incidence and severity than the other treatments. However, multilocational field studies should be conducted to validate the findings of the current study, so that these bioagents can be formulated and made available to the farming community. | |
| dc.identifier.uri | https://krishikosh.egranth.ac.in/handle/1/5810208469 | |
| dc.keywords | Plant Pathology | |
| dc.keywords | Vigna unguiculata (L.) Walp. | |
| dc.keywords | anthracnose disease of Cowpea | |
| dc.language.iso | English | |
| dc.pages | 84p. | |
| dc.publisher | Department of Plant Pathology, College of Agriculture ,Vellanikkara | |
| dc.sub | Plant Pathology | |
| dc.theme | the research project entitled “Phyllosphere microorganisms for the management of anthracnose disease of cowpea (Vigna unguiculata (L.) Walp.).” was carried out. Phyllosphere microbiome enhance plant tolerance to withstand biotic and abiotic stress conditions in the current facet of climate change. | |
| dc.these.type | M.Sc | |
| dc.title | Phyllosphere microorganisms for the management of anthracnose disease of Cowpea (Vigna unguiculata (L.) Walp.) | |
| dc.type | Thesis |