Manifestation of Heterosis for Yield and Component Traits in Rice (Oryza sativa L.) under Temperate Environment

Hybrid rice technology offers a readily available opportunity to increase the productivity of rice in acceptable manner. In present study, 36 cross combinations developed by crossing two CMS lines with 18 testers in line x tester mating design were evaluated to find out best heterotic combinations in terms of yield and yield components. Assessment of heterosis based on standard checks (SR-1 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. All combinations that showed superiority over standard checks for grain yield per plant (ranged from 25.88% to 55.70%), also showed significant heterosis for majority of other traits. The best cross combination in terms of grain yield was SKAU7A x K-08-61-2 and for early maturity SKAU11A x SR-2 over check SR-1 only. Cross combinations SKAU 7A x K-08-61-2, SKAU 7A x SR-2, SKAU 11A x K-08-60-2, SKAU 11A x K-08-59-3 and SKAU 11A x SKAU-389 were found to be good specific combinations for grain yield per plant and other desirable traits and need to be tested on large scale for their commercialisation under temperate conditions.