Variability, gene effects and inheritance of harvest index in crosses of wheat genotypes with different Rht genes

The objectives of this study were to investigate the variability, gene effe cts and mode of inheritance of harvest index in the crosses of wheat genoty pes earring different Rht genes. The parents used in the crosses were Siete Cerros (Rht-B1b), Aobakomughi (R ht-D1b), Tom Thumb (Rht-B1c), Ai-bian 1, (Rht-D1c) Sava (Rht 8) and Bankuty 1205 (rht). The data recorded for the F-1 and F-2 generations suggests tha t promissing crosses for selection of genotypes towards increased harvest i ndex (HI) are Bankuty 1205/Aobakomughi, Bankuty 1205/Sava and Sava/Ai-bian 1. For the crosses Bankuty 1205/Aobakomughi and Bankuty 1205/Sava additive- dominant model was adequate for determination of gene efects. For both cros ses higher effects of dominant genes compared to additive once have been re corded. In the crosses Siete Cerros/Ai-bian 1 and SavalAi-bian 1 KI was det ermined by additive as well as additive/ dominant [j] epistatic gene effect . For the crosses Bankuty 1205/Aobakomughi and Bankuty 1205/ Sava the mode of inheritance of HI was overdominance of the parent with higher mean value (Bankuty 1205) and for the cross Sava/Ai-bian, overdominance of the parent with lower mean value(Sava). In crosses Siete Cerros/Ai-bian 1 and Siete C erros/Tom Thumb superdominance of parent with lower mean value of HI (negat ive heterozis) have been determined.