Epidemiology, Molecular Characterization for Resistance to Turcicum Leaf Blight and Integrated Management of Major Foliar Diseases in Maize
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Date
2016-08
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University of Agricultural Science, Dharwad
Abstract
Survey was conducted during two kharif and rabi seasons (2014-15 and 2015-16) in northern Karnataka for recording foliar diseases severity. Among the foliar fungal diseases of maize turcicum leaf blight (TLB) caused by Exserohilum turcicum is major yield limiting factor. Survey study revealed that maximum disease severity (96.00 PDI) of TLB was noticed in Gurlapur village of Belagavi district. Kalburgi district remained free from all foliar diseases even at the cob formation stage. The maximum severity of TLB was recorded in 2014 kharif compared to 2015. Thirty isolates collected during survey showed morphological variation on PDA. The full length ITS rDNA region of E. turcicum was amplified with ITS-1 and ITS-4 primers. Genetic variation among isolates of E. turcicum was studied by analysis of the ITS-RFLP profile after the digestion with restriction enzymes (Taq I, and Hind II) which showed specific polymorphism.
Field experiments were undertaken during two kharif seasons at MARS, Dharwad (2014 and 2015). Among 23 inbred lines screened under artificial epiphytotic condition, three lines (PDM-74-1, 4641 and 260) exhibited moderate resistant reaction.The application of different SSR markers successfully provided the information on similarity and/or diversity as well as the heterozygosity of the allelic loci for all the 23 inbred lines. Epidemiological study revealed a positive correlation with cumulative rainfall and temperature. The multiple linear regression equation was developed and the coefficient of determinative value (R2) was more than 0.90 in two consecutive kharif seasons.
In the fungicidal management of TLB, spraying of propiconazole @ 0.1 per cent at 35, 50 and 65 days after sowing recorded least PDI (12.44) with maximum grain and fodder yield (73.01 q/ha and 10.33 t/ha). In the four integrated disease management modules, highest grain and fodder yield were recorded in chemical module (72.40 q/ha and 9.01 t/ha) with 2.58 B:C ratio.