Nautiyal, M.K.Bisht, Meenakshi2018-10-222018-10-222014-07http://krishikosh.egranth.ac.in/handle/1/5810081876The present investigation was carried out during kharif 2012 at the Norman E Borlaug Crop Research Centre, G.B. pant University of Agriculture and Technology. The study compromised of thirty-one elite lines, three testers (IR 58025A, Pusa 6A and Pant CMS 2A), one standard check (Pant Dhan 12) and ninety-three F1 hybrids. All the material was planted in Randomized Complete Block Design (RCBD) with two replications following line x tester mating design. The objectives of the present study were (i).To estimate the combining ability of CMS lines and crosses, (ii).To estimate the nature and magnitude of heterosis, and (iii). To identify superior maintainers and restorers for development of potential CMS lines and hybrids. Analysis of variance for combining ability revealed importance of non-additive gene action in the expression of various characters. The results indicated that the NDR 1425 (L5), CR 2648-6-3-2 (L7), UPR 2642-31-1-1 (L22) and KPH 371(L31) were the best combiners among lines as evident from significant GCA effects for high number of yield contributing characters and some parents showing maximum per se performance were also the best general combiner for the characters i.e. Pusa 1592-06-5-2 (L20) for panicle length, NDR 1425 (L5) and Pusa 1509-03-1-7-2 (L18) for 1000 grain weight, R 1530-1546-1-418-1 (L3) for filled grains per panicle, IRBBN 90 (L27) for unfilled grains per panicle. Moderate to high degree of heterobeltiosis and standard heterosis were recorded for grain yield per plant and most of its components. The per cent standard heterosis, for grain yield ranged between -86.397 to 33.272 per cent, suggesting good scope for identifying heterotic crosses for exploitation in optimum fertility conditions. The best heterotic hybrids, UPR 3729F6-2-4-4 x IR 58025 A (L23 x T1), MTU 1121 x Pusa 6A (L15 x T2), R 1530-1546-1-418-1 x Pusa 6A (L3 x T2) and UPR 3425-11-1-1 x IR 58025 A (L1 X T1) in normal conditions expressing higher SCA effects and per se performance, also involved good/ good combining parents into them. These crosses may be suggested for straight use in hybrid breeding. On the basis of spikelet fertility percent, lines were grouped as maintainer, restorer and partial restorer/maintainer lines. Among thirty one lines, none of the lines behave as maintainer and restorer with all the three CMS lines (IR 58025 A, Pusa 6A and Pant CMS 2A), six lines viz . , L4, L9, L10, L14, L15 and L25 behave as maintainers with both IR 58025 A and Pusa 6A CMS lines and rest behave like partial restorer/ maintainer lines.ennullThesis