No abstract

The present research investigation was conducted in order to analyze combining ability and nature of gene actions in 33 F1s of bread wheat (Triticum aestivum L. em. Thell) developed by crossing eleven lines with three testers in a line x tester mating design in terms of grain yield and associated traits. The hybrids along with the parental lines and two check varieties were planted in a randomized block design in three replications. Variance ratio between general and specific combining ability was found to be less than unity which indicated the prevalence of non-additive gene actions involved in the inheritance of these characters. Parental lines QLD 75 (3.164), followed by SOKOLL (2.888) and QLD 65 (2.819) exhibited significant GCA for grain yield, while another line PRL/2*PASTOR*2//FH6-1-7/3/KINGBIRD#1//… was observed to be the better general combiner for most other traits including maturity. Among the hybrids cross combination NAC/TH.AC//3*PVN/3/MIRLO/BUC/4/2*PASTOR/5/…x HD 3237 showed significant higher positive SCA for grain yield and biological yield per plant, whereas, F1 QLD 75 x HI 1621was a good specific combiner for harvest index (%) and number of grains per spike. The cross combination VORB/4/D67.2/PARANA66.270 x PBW 725 was observed with significant higher positive SCA for days to 75% heading, days to maturity and plant height, and another hybrid VORB/4/D67.2/PARANA 66.270 x HI 1621 exhibited significant positive SCA for 1000 grain weight and spike length.

Eleven genotypes of bread wheat were crossed with three testers in the rabi season of 2018-19 inline x tester mating fashion to obtain 33 F1 hybrids, which were evaluated with parents and two standard checks of wheat viz., UP 2855 and HD 2967. The experiment was laid out in randomized block design with three replications at Norman E. Borlaug Crop Research Centre, G.B. Pant University of Agriculture and Technology, Pantnagar in the rabi season 2019-20. Observations were recorded on various qualitative and quantitative characters including grain yield. The results obtained revealed significant differences among all the genotypes, indicating the presence of aconsiderable amount of genetic variability. The cross combinations SOKOLL x HI 1621, followed by QBP 12-11 x HI 1621, NAC/TH.AC//3*PVN/3/MIRLO/BUC/4/ 2*PASTOR/5/… x HD 3237 were observed to be the better heterotic F1s in terms of grain yield. The hybrid QLD 75 x HI 1621 was identified as the best heterotic combination for grain weight per spike and harvest index. Whereas, for grains per spike F1, NW 6036 x HI 1621, for 1000 grain weight F1, SOKOLL x HD3237, for spike length F1, NAC/TH.AC//3*PVN/3/ MIRLO/BUC/4/2*PASTOR/5/… x HD 3237, for peduncle length F1, VORB/4/D67.2/PARANA 66.270 x HI 1621 and for days to 75% heading and days to maturity F1, PRL/2*PASTOR*2//FH6-1-7/3/KINGBIRD#1//… x PBW 725 were observed to be the better heterotic combinations. The crosses with higher heterotic values may provide an opportunity for isolation of desirable purelines in advanced generations.