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20193
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Author: Luikham, Star × Start date: 2000 ×
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    ThesisItemOpen Access
    MOLECULAR CHARACTERIZATION OF AROID GERMPLASMS OF NORTH EAST INDIA – ASSESSMENT OF HOST RESISTANCE AND BIOLOGICAL MANAGEMENT OF BACTERIAL BLIGHT DISEASE
    (2019) Luikham, Star; Bora, L. C.
    Bacterial blight disease of Taro incited byXanthomonasaxonopodispv. dieffenbachia (Xad) is a quarantine importance causing extensive damage and loss to the crop in recent decades. The present study was attempted to collect, conserve and characterize the aroid cultivars/ germplasms of North East (NE) India based on 29 RAPD markers, to find out the resistant cultivars/ germplasms amongst them and also in controlling the disease through microbial based biopesticides. 64 Taro cultivars/ germplasm collected from different regions of NE along with two national released varieties,viz.,‘Muktakeshi’ and ‘SreeKiran’ as check varieties were grouped into two main clusters based on RAPD markers.Colony and morphological studies, biochemical and pathogenicity test, Field emission scanning electron microscope (FESEM)and molecular studies confirmed that the pathogen isolated from infected plant parts of colocasia was Xadwhich was short rod-shaped.Screening of the various cultivars/ germplasms against Xadin actual field condition was performed based on the disease severity and disease rating scaleand revealed that the number of resistant, moderately resistant, moderately susceptible and susceptible cultivars were 4, 21, 26 and 15 respectively, while none of the germplasms were immune and highly susceptible to the disease.Disease severity per cent ranged from 14.17 % (Nepali-2) – 67.50 % (SC-1).In vitro studies of the various bioagent combinations for four bio-formulations (Biofor-pf, Bio-time, Biogreen-5, Biozin-PTB) along with streptocycline@100 ppm as chemical check were evaluated against Xad. Highest per cent inhibition (66.22 %) was observed for the combination of five bio-agents, viz., Trichodermaviride, Beauveriabassiana, Metarhiziumanisopliae, Pseudomonas fluorescensandBacillus thuringiensis. Two moderately susceptible germplasms, i.e. ‘Pijayikochu’ and ‘SC-1’ were selected and the four bio-formulations along with streptocycline@100 ppm were evaluated for their efficacy against Xadunder pot condition, by applying these as corm treatment, soil application and foliar spray. Highest disease reduction for ‘Piyajikochu’ (71.42 %) and ‘SC-1’(72.69 %) as well asyield and yield attributing characters were recorded for the bioformulation Biogreen-5 comprising of the five bio-agents while the highest corm and cormels yield (g/plant) recorded were 1194.47 (Pijayikochu) and 1039.06 (SC-1). The present study seems to be the first report for screening of different Taro cultivars/ germplasm against bacterial blight of colocasia under field condition. Exploration of different microbe based biopesticides also seems to be the first report of investigation for controlling the disease.
  • Thumbnail Image
    ThesisItemOpen Access
    MOLECULAR CHARACTERIZATION OF AROID GERMPLASMS OF NORTH EAST INDIA – ASSESSMENT OF HOST RESISTANCE AND BIOLOGICAL MANAGEMENT OF BACTERIAL BLIGHT DISEASE
    (AAU, Jorhat, 2019) Luikham, Star; Bora, L. C.
    Bacterial blight disease of Taro incited by Xanthomonas axonopodis pv. dieffenbachia (Xad) is a quarantine importance causing extensive damage and loss to the crop in recent decades. The present study was attempted to collect, conserve and characterize the aroid cultivars/ germplasms of North East (NE) India based on 29 RAPD markers, to find out the resistant cultivars/ germplasms amongst them and also in controlling the disease through microbial based biopesticides. 64 Taro cultivars/ germplasm collected from different regions of NE along with two national released varieties, viz., ‘Muktakeshi’ and ‘Sree Kiran’ as check varieties were grouped into two main clusters based on RAPD markers. Colony and morphological studies, biochemical and pathogenicity test, Field emission scanning electron microscope (FESEM) and molecular studies confirmed that the pathogen isolated from infected plant parts of colocasia was Xad which was short rod-shaped. Screening of the various cultivars/ germplasms against Xad in actual field condition was performed based on the disease severity and disease rating scale and revealed that the number of resistant, moderately resistant, moderately susceptible and susceptible cultivars were 4, 21, 26 and 15 respectively, while none of the germplasms were immune and highly susceptible to the disease. Disease severity per cent ranged from 14.17 % (Nepali-2) – 67.50 % (SC-1). In vitro studies of the various bioagent combinations for four bio-formulations (Biofor-pf, Bio-time, Biogreen-5, Biozin-PTB) along with streptocycline@100 ppm as chemical check were evaluated against Xad. Highest per cent inhibition (66.22 %) was observed for the combination of five bio-agents, viz., Trichoderma viride, Beauveria bassiana, Metarhizium anisopliae, Pseudomonas fluorescens and Bacillus thuringiensis. Two moderately susceptible germplasms, i.e. ‘Pijayi kochu’ and ‘SC-1’ were selected and the four bio-formulations along with streptocycline @100 ppm were evaluated for their efficacy against Xad under pot condition, by applying these as corm treatment, soil application and foliar spray. Highest disease reduction for ‘Piyaji kochu’ (71.42 %) and ‘SC-1’(72.69 %) as well as yield and yield attributing characters were recorded for the bioformulation Biogreen-5 comprising of the five bio-agents while the highest corm and cormels yield (g/plant) recorded were 1194.47 (Pijayi kochu) and 1039.06 (SC-1). The present study seems to be the first report for screening of different Taro cultivars/ germplasm against bacterial blight of colocasia under field condition. Exploration of different microbe based biopesticides also seems to be the first report of investigation for controlling the disease.
  • Thumbnail Image
    ThesisItemOpen Access
    MOLECULAR CHARACTERIZATION OF AROID GERMPLASMS OF NORTH EAST INDIA – ASSESSMENT OF HOST RESISTANCE AND BIOLOGICAL MANAGEMENT OF BACTERIAL BLIGHT DISEASE
    (AAU, Jorhat, 2019) Luikham, Star; Bora, L. C.
    Bacterial blight disease of Taro incited by Xanthomonas axonopodis pv. dieffenbachia (Xad) is a quarantine importance causing extensive damage and loss to the crop in recent decades. The present study was attempted to collect, conserve and characterize the aroid cultivars/ germplasms of North East (NE) India based on 29 RAPD markers, to find out the resistant cultivars/ germplasms amongst them and also in controlling the disease through microbial based biopesticides. 64 Taro cultivars/ germplasm collected from different regions of NE along with two national released varieties, viz., ‘Muktakeshi’ and ‘Sree Kiran’ as check varieties were grouped into two main clusters based on RAPD markers. Colony and morphological studies, biochemical and pathogenicity test, Field emission scanning electron microscope (FESEM) and molecular studies confirmed that the pathogen isolated from infected plant parts of colocasia was Xad which was short rod-shaped. Screening of the various cultivars/ germplasms against Xad in actual field condition was performed based on the disease severity and disease rating scale and revealed that the number of resistant, moderately resistant, moderately susceptible and susceptible cultivars were 4, 21, 26 and 15 respectively, while none of the germplasms were immune and highly susceptible to the disease. Disease severity per cent ranged from 14.17 % (Nepali-2) – 67.50 % (SC-1). In vitro studies of the various bioagent combinations for four bio-formulations (Biofor-pf, Bio-time, Biogreen-5, Biozin-PTB) along with streptocycline@100 ppm as chemical check were evaluated against Xad. Highest per cent inhibition (66.22 %) was observed for the combination of five bio-agents, viz., Trichoderma viride, Beauveria bassiana, Metarhizium anisopliae, Pseudomonas fluorescens and Bacillus thuringiensis. Two moderately susceptible germplasms, i.e. ‘Pijayi kochu’ and ‘SC-1’ were selected and the four bio-formulations along with streptocycline @100 ppm were evaluated for their efficacy against Xad under pot condition, by applying these as corm treatment, soil application and foliar spray. Highest disease reduction for ‘Piyaji kochu’ (71.42 %) and ‘SC-1’(72.69 %) as well as yield and yield attributing characters were recorded for the bioformulation Biogreen-5 comprising of the five bio-agents while the highest corm and cormels yield (g/plant) recorded were 1194.47 (Pijayi kochu) and 1039.06 (SC-1). The present study seems to be the first report for screening of different Taro cultivars/ germplasm against bacterial blight of colocasia under field condition. Exploration of different microbe based biopesticides also seems to be the first report of investigation for controlling the disease.