Tak, Parminder SinghRubleen Kaur2024-01-032024-01-032023Rubleen Kaur (2023). Biodiversity of seed-borne pathogenic mycoflora of wheat (Triticum aestivum L.) in Punjab (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810205593A total 105 grain markets of 23 districts of Punjab were surveyed for study of seed-borne mycoflora during 2021-22 and 654 grain samples were collected. Grains were visually inspected for incidence of Karnal bunt (KB), Black point (BP) and shrivelling. Prevalence of Karnal bunt, Black point and shrivelled grains was 10.24%, 55.20% and 79.51 per cent, respectively. Grain samples from Patiala and Mansa were found to have statistically lowest KB, black point and shrivelled seeds while highest incidence was observed in Pathankot followed by Hoshiarpur and Mohali. Three pathogenic and nine opportunistic fungi were isolated from these samples. Fungal diversity in Sarhali Kalan samples (66.67%) was highest, followed by Sirhind-1, Jalandhar, Rajpura (58.3% each). Bikhi, Nabha, Dadehra, Bucho mandi, Panjgrain (16.67%) carried low mycoflora load. All the samples collected met the minimum seed certification standards for germination. Maximum vigour index I and II of 3327.6 and 26.46 was observed in grain samples collected from Doraha-1 and Shahkot, respectively. Prevalence of Alternaria spp. (94%) was highest followed by Fusarium spp. (64%), Aspergillus flavus (48%) whereas, low prevalence was observed for Exserohilum sp. and Leohumicola sp. (2% each). The fungal isolates were characterized on the basis of morphology and cultural characteristics into 11 fungal genera belonging to 7 families which included Alternaria alternata, Bipolaris sorokiniana, Curvularia verrucosa, Curvularia spicifera and Exserohilum rostratum from Pleosporaceae family (34%); Aspergillus flavus, A. japonicus and Penicillium digitatum, from Aspergillaceae (17%); Fusarium equiseti from Nectriaceae (8%); Epicoccum purpurascens from Didymellaceae (8%); Leohumicola sp. from Incertae sedis (8%), Chaetomium globosum and Pseudothielavia terricola from Chaetomiaceae (17%) and Rhizopus stolonifer from Rhizopodiaceae (8%). Sequencing of Curvularia verrucosa, Bipolaris sorokiniana, Curvularia spicifera, Aspergillus japonicus, Pseudothielavia terricola, Alternaria alternata and Fusarium equiseti was done and cultures have been deposited in MTCC repository, Chandigarh. Thirty nine fungal isolates were inoculated on three wheat varieties and determined for seed health, foliar blights and carryover studies. Opportunistic fungi such as Curvularia sp. (isolate CUS-1), Aspergillus sp. (isolates AF-1, AF-7), Rhizopus sp. (RIZO-1), Penicillium sp. were found to reduce germination under field conditions. Highest average foliar blight severity was observed in Gurdaspur (26.98%) as compared to 20.60 per cent in Ludhiana. Bipolaris isolate BIS-1, Aspergillus flavus AF-1, Curvularia CUT-1, Alternaria ALT-6 and ALT-10 resulted high severity in Ludhiana while Fusarium FUS-1, Rhizopus RIZO-1, Drechslera DRH-3, Aspergillus flavus AF-7 and Alternaria ALT-8 were highly pathogenic in Gurdaspur. The seed inoculated with these fungi induced foliar blight, affected the germination as well as severity of foliar blight however, they could not be re-isolated in all the cases indicating their primary role only up to seedling stage. Overall, Alternaria spp. had the highest frequency in grain market samples as well as carryover studies.EnglishThesis