Exploitation of heterosis in rice (Oryza sativa L.) using CMS system under temperate conditions

The present study was conducted to evaluate 36 cross combinations developed by crossing 2 CMS lines with 18 testers in line x tester mating design to identify effective restores and maintainers from elite lines and work out best heterotic combinations in terms of yield and yield components. Assessment of standard heterosis based on standard checks (SR1 and Jhelum) of effectively restored cross combinations showed that there was significant heterosis for all the traits except number of filled grains per panicle and the degree of heterosis varied from trait to trait. The entire cross combinations that showed superiority over standard checks for grain yield per plant also showed significant heterosis for majority of other traits. The best cross combination in terms of grain yield was SKAU7A x K08612 and for early maturity SKAU11A x SR2 over check SR1 only. In terms of restoration ability of genotypes 3 lines were categorized as effective restores viz. K08612, K08602 and SR2 and 5 lines were categorized as maintainers viz. SKAU405, Jhelum, SKAU407, China1007 and SKAU391. The average proportion of restorers, partial restorers, partial maintainers and maintainers were 16:22:33:27, respectively.