Shanthakumar G.Purushottam Y.2022-08-082022-08-082017-07https://krishikosh.egranth.ac.in/handle/1/5810186138An investigation was carried out to assess the heterosis, combining ability and screening against turcicum leaf blight (TLB) in six inbred lines of maize using a diallel mating design (without reciprocal crosses). The six elite inbred lines viz., DMIT 121, DMIT 123, DMIT 124, DMIT 125, DMIT 113 and DMIT 118 are crossed in all possible combinations in half diallel fashion. The experiment was set up in a randomized complete block design (RCBD) with 3 replications during kharif season of 2016-17 at the Maize Research Centre, Devihosur, Haveri district, which comes under UAS, Dharwad, Karnataka. The combining ability analysis revealed presence of higher magnitude of SCA variance than GCA variance indicating predominance of non-additive gene action for all the traits except days to tasseling and silking. GCA studies revealed that the lines DMIT 123 and DMIT 118 were having good GCA for most of yield and its contributing traits as they showed significant GCA effects. Hence, these lines can be used in various hybrid breeding programmes to increase maize grain yield with superior ear traits. The crosses DH 1514, DH 1506 and DH 1501 were best specific combiners for grain yield with highest SCA effects 39.81, 28.54 and 22.6, respectively. As these crosses having one of their parents with good general combiner for all the traits having H × L or L × H GCA status indicating dominance and epistatic interactions. Field screening studies indicated there was clear difference in disease response to TLB due to good infection through artificial inoculation. The hybrids DH 1515, DH 1514 and DH 1505 categorized as highly resistant with PDI 2.13, 2.5 and 4.00 respectively, for TLB. Both the parents of these hybrids were resistant with disease score of 1 and less per cent disease index showing highly resistant reaction against turcicum leaf blight.EnglishThesis