Line × Tester Analysis for Yield and Yield Components in Rice Lines

General and specific combining ability of some rice lines and cultivars with IRRI sources were determined using the line × tester procedure (5 pure lines were crossed with 4 local cultivars as tester). Parents and their progenies were planted in a randomized complete block design with three replications in the research field of Iran Rice Research Institute. Traits such as yield and its components were recorded. Analysis of variance showed significant differences among genotypes for all traits but panicle/plant. Line x tester analysis showed that lines effect was significant for all traits at 1% level and the tester’s effect was significant for all traits but seeds/panicle at the 1% level. The significance of the line × tester effect in all of the traits except plant height، flag leaf width and seed length indicated that lines’ response was different depending on the tester they were crossed to various testers. The line PR 27137-CR 153 (with an average yield of 5. 045 t/h) had highest GCA and the cross Hassani × IR 73688-57-2 (with an average yield of 5. 613 t/h) had the highest and significant SCA. The amount of additive and non-additive variances varied in different traits resulting in a different heritability estimate. Narrow-sense heritability for most of the traits was low. The highest narrow-sense heritability was observed for the seed length (0. 27).