Devi, R. K. TombisanaThokchom, Christina2023-03-222023-03-222022-07https://krishikosh.egranth.ac.in/handle/1/5810195661Among the major diseases of carrot, white mould constitutes an important one which is prevalent worldwide. In this study, extensive surveys were conducted during August-September, 2021 in two different districts of Meghalaya i.e., Ri- Bhoi and East Khasi Hills districts in which disease incidence in the range of 3.9-8.36% was recorded. Laitjem village of East Khasi Hills showed maximum disease incidence of 8.36%. The correlation studies of disease incidence with weather parameters (maximum and minimum temperature, evening and morning relative humidity and rainfall) revealed that temperature and rainfall had positive relation with disease incidence for both the districts. In the market surveys conducted twice in the above two districts, disease incidence ranging from 25 to 30.47% was recorded and Bara bazaar of East Khasi Hills was recorded for highest incidence (30.47% and 30.28%) in both the surveys. Fungal pathogen associated with the disease was isolated and confirmed as Sclerotinia sclerotiorum based on morphology studies and pathogenecity test of the isolated pathogen. Twenty five endophytic (ECarrot) and twenty five biofertilizing (BCarrot) bacteria were isolated from healthy carrots and soil respectively collected from different carrot growing areas of the surveyed districts. Dual culture assay of the isolates against S. sclerotiorum revealed that ECarrot9 showed maximum mycelia inhibition of 72.15% followed by BCarrot21 (65.59%), ECarrot16 (60.33%) and BCarrot8 (50.89%). Based on antagonistic potential and plant growth promoting activities, two efficient endophytes (ECarrot9 and ECarrot16) and two biofertilizers (BCarrot8 and BCarrot21) were chosen for further evaluation in the field. ECarrot9, ECarrot16, BCarrot8 and BCarrot21 were identified as Bacillus amyloliquifaciens, Stenotrophomonas maltophilia, Burkholderia ambifaria and Bacillus megaterium respectively based on 16S rRNA sequencing. All these four isolates were found to be compatible and formulated 5 consortia. Out of these, four consortia consisting of two isolates each and one consisting of all the isolates. Field evaluation at different treatment combinations showed that T10 (seed treatment with Saaf) gave lowest disease index of 1.38%. However T9 (consortium consisting of all the isolates) gave disease index of 4.16% as compared to T11 (control) which gave disease index of 19.44%. T9 significantly improved plant growth (9.33 cm) and yield upto 93.33 q/ha. Studies on mass production of the consortium with efficient carrier system may be subsequently taken up in order to provide a safer and efficient management of the disease even in post harvest conditions.EnglishThesis