Management of Penicillium rot of Khasi Mandarin (Citrus reticulata Blanco) by using native Bacillus subtilis isolates
| dc.contributor.advisor | Majumder, Dipali | |
| dc.contributor.author | Tariang, Janshame | |
| dc.date.accessioned | 2023-02-01T09:52:04Z | |
| dc.date.available | 2023-02-01T09:52:04Z | |
| dc.date.issued | 2019-11 | |
| dc.description.abstract | Mandarin orange is an important horticulture crop in India next to banana. Amongst a variety of mandarin, Khasi mandarin is widely cultivated in the North-Eastern (NE) states of India, particularly in the border areas of Meghalaya which is very popular due to its unique quality, fruit colour, sugar-acid blend and shelf life. Although Meghalaya is one of the largest producers of orange in the country, due to the problem of post-harvest diseases, there have been considerable losses to the harvested fruits and the average yield of Khasi mandarin is alarmingly low. Several losses of the fruit have been reported due to post-harvest disease Penicillium rot caused by Penicillium. spp. The present investigation was formulated with an aim to minimise the loss of the Khasi mandarin fruit due to the post-harvest disease Penicillium rot by using native B. subtilis isolates. Samples were obtained from 15 different natural habitats (crop rhizosphere, hot springs, pig manure, river bank deposits, citrus fruit surfaces, mixed manure, coal mines, limestone mines, forest, leave mould, vermi-compost, fishery ponds, oyster mushroom compost, jhum area and from bio-extract) of the 8 districts of Meghalaya (West Jaintia Hills, East Khasi Hills, Ri- Bhoi, West Garo Hills, North Garo Hills, West Khasi Hills, East Jaintia Hills and South West Garo Hills). A total of 260 isolates was collected, maximum of which was obtained from West Jaintia Hills district (94 isolates) and a majority was isolated from the rhizosphere of crops (181 isolates). Based on the morphological characters of the colonies and biochemical test viz. Gram staining test, catalase and oxidase test, 95 isolates were initially designated as B. subtilis. Further molecular identification of these isolates was done using 16S rRNA intervening sequence Bacillus genus specific primer BCF1/BCR2 which identified 69 isolates as Bacillus spp. To further confirm the isolates as B. subtilis, species specific primer EN1F/RN1R was used which further confirmed 12 isolates as B. subtilis (Bs 80, Bs 167, Bs 174, Bs 190, Bs 193, Bs 197, Bs 216, Bs 217, Bs 219, Bs 256, Bs 257 and COB5Y1). These 12 B. subtilis isolates were studied for their antimicrobial traits and all the 12 isolates were found to be negative for HCN production, negative to the presence of antibiotic biosynthetic genes coding for iturin D and fengycin B, whereas 6 isolates were positive for catalase production test and 10 isolates were positive for protease production test. Six B. subtilis isolates viz. Bs 167, Bs 197, Bs 217, Bs 219, Bs 256 and COB5Y1 were considered potential based on the antimicrobial test. Bio-assay of these 12 B. subtilis isolates against Penicillium rot pathogen of Khasi mandarin fruit revealed that maximum disease inhibition per cent against Penicillium spp. was recorded for the isolate COB5Y1 (88.11%), followed by isolate Bs 167 (80.82%), Bs 197 (54.82%) and Bs 217 (40.19%). Based on in-vitro evaluation, isolates COB5Y1, Bs 167, Bs 197 and Bs 217 were considered potential B. subtilis isolates amongst 12 B. subtilis isolates tested. Four isolates (COB5Y1, Bs 167, Bs 197 and Bs 217) were selected for field evaluation based on their performance against antimicrobial test and dual culture test. Amongst these four B. subtilis isolates, two isolates Bs 167 and COB5Y1 showed maximum disease inhibition per cent with 78.75% (21.25% disease incidence) and 65% (35% disease incidence) respectively even after storage of the fruit for upto 30days when the bio-agent was applied as liquid formulation at post-harvest stage of the fruit. There was no significant difference with the point of inoculation of the pathogen for disease development. B. subtilis isolates (COB5Y1, Bs 167, Bs197 and Bs 217) were also found to have no adverse effect on the post-harvest fruit quality such as mass loss, TSS and acidity of the fruit. The viability test revealed that B. subtilisisolates were found most viable when stored at 4°C upto 180 days. Two isolates Bs 167 and COB5Y1 were regarded as effective antagonists that could serve as potential bio-agent against Penicillium rot of Khasi mandarin in Meghalaya which need further evaluation under field condition Meghalaya. | en_US |
| dc.identifier.uri | https://krishikosh.egranth.ac.in/handle/1/5810193036 | |
| dc.keywords | Khasi mandarin, B. subtilis, Penicillium rot, habitat, bio-control, Meghalaya. | en_US |
| dc.language.iso | English | en_US |
| dc.pages | [17], 108p. | en_US |
| dc.publisher | College of Post Graduate Studies in Agricultural Sciences, CAU-Imphal, Umiam | en_US |
| dc.sub | Plant Pathology | en_US |
| dc.subject | Biological control | en_US |
| dc.subject | Mandarins | en_US |
| dc.theme | Academic Research | en_US |
| dc.these.type | Ph.D | en_US |
| dc.title | Management of Penicillium rot of Khasi Mandarin (Citrus reticulata Blanco) by using native Bacillus subtilis isolates | en_US |
| dc.type | Thesis | en_US |