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 xtester mating design to identify effective restores and maintainers from elite lines and work out best heterotic combinations interms of yield and yield components. Assessment of standard heterosis based on standard checks (SR-1 and Jhelum) ofeffectively restored cross combinations showed that there was significant heterosis for all the traits except number of filled grainsper panicle and the degree of heterosis varied from trait to trait. The entire cross combinations that showed superiority overstandard checks for grain yield per plant also showed significant heterosis for majority of other traits. The best cross combinationin terms of grain yield was SKAU7A x K-08-61-2 and for early maturity SKAU11A x SR-2 over check SR-1 only. In terms ofrestoration ability of genotypes 3 lines were categorized as effective restores viz. K-08-61-2, K-08-60-2 and SR-2 and 5 lineswere categorized as maintainers viz. SKAU-405, Jhelum, SKAU-407, China-1007 and SKAU-391. The average proportion ofrestorers, partial restorers, partial maintainers and maintainers were 16:22:33:27, respectively.