Bhardwaj, Rachana D.Simardeep Kaur2019-07-092019-07-092019http://krishikosh.egranth.ac.in/handle/1/5810113496In the present investigation, leaves of six barley genotypes namely PL 807, BH 946, DWRUB 52, BL 1338, BL 1369 and PL 426 inoculated with Bipolaris sorokiniana were evaluated for antioxidant potential, levels of H2O2, MDA, antioxidative enzymes, non-enzymatic antioxidants, pathogenesis- related (PR) proteins and β-glucan. The disease severity was assessed at two different stages viz. GS 55 and GS 87 during 2017-18 and 2018-19. The genotype BL 1369 showed moderately resistant, PL 807 and BL 1338 moderately susceptible and the other genotypes demonstrated susceptible behavior after fungal infection. On fungal inoculation, an increase in total phenols, flavonoids, carotenoids along with the free radical scavenging activities (DPPH, NO, FRAP) was reported in BL1369 and BL 1338 during GS 55 stage whereas, in PL 807 and PL 426, decrease of DPPH. and NO. scavenging capacities and total phenols was observed. During GS 87 stage, maximum increase of catalase, ascorbate peroxidase, glutathione reductase, phenylalanine ammonia lyase, tyrosine ammonia lyase and polyphenol oxidase activities alongwith concomitant decrease of H2O2 content in the infected lower leaves of BL 1369 could be responsible for its moderately resistant behaviour. Although on fungal inoculation, chitinase activity increased in all the genotypes except DWRUB 52 and BL 1338 but maximum increase was reported in BL 1369. β-glucanase activity also increased significantly in all the leaf tissues of BL 1369. The β-glucan content decreased in DWRUB 52 and PL 426 upon fungal infection while it increased in BL 1338 and BL 1369.ennullThesis