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The experiment was aimed at assessing the response of 30 rice genotypes to different levels of salinity using NaCl concentration as salt stress at early seedling stage under hydroponic conditions. The experiment was replicated three times in a Completely Randomized Design for two years. The 30 rice genotypes evaluated for root length, fresh root weight, dry root weight, shoot length, fresh shoot weight, dry shoot weight, seedling biomass and shoot/root length ratio. The four salinity treatments/levels (0, 4, 6 and 12 dS/m) significantly affected the response of the 30 rice genotypes for all the traits evaluated. The interaction between salinity treatments and the genotypes was significant for all traits except fresh root weight, shoot length and dry shoot weight. The genotypic response revealed reduction in performance as the salinity level increases for all the traits, 10 genotypes were tolerant at all salinity levels. The most affected seedling trait due to salinity stress was seedling biomass at 6 dS/m (54.84%) and was expressed by genotype IR29 (susceptible check), followed by ROK 24 at 12 dS/m (54.43%). Eight rice genotypes; CK73, ITA212 (FARO 35), ITA222 (FARO 36), OG0315, OG250315, OW0315, TOG 5681 and Pokkali (Tolerant Check) were classified highly tolerant by both Stress Tolerance Index (SST) and Stress Susceptible Index (SSI), while FARO 61 (NERICA L -34) and IR72 were moderately tolerant. These rice genotypes have good potentials for further salt tolerance breeding.

Salinity is a major abiotic constrain faced by farmers in most rice cultivating areas of the world and improving grain yield in rice is the most important breeding objective. Twenty seven hybrids were generated in a line x tester mating design and were evaluated with their parents in a Randomized Complete Block Design at the Fadama site of the Federal University of Agriculture, Abeokuta (FUNAAB) during the 2014/2015 and 2015/2016 cropping season. Analysis of variance revealed a highly significant difference (P0.01) among testers and lines for all traits except panicle length and a number of effective tillers per plant, respectively. Variances of Specific Combining Ability (SCA) were higher in magnitude than the corresponding General Combining Ability (GCA). The lines FARO 60 (P7), OG300315 (P10), NERICA L53 (P4) including a tester ITA 212 (P1) were the best general combiners for yield per plant. POKKALI (P3) was the best general combiner for reduced vegetative growth and ITA 212 (P1) and ITA 222 (P2) were the best general combiners for plant height. The best specific combiner for yield per plant was P1 x P4. P3 x P11 was the best specific combiner for reduced duration characters and P2 x P7 was the best specific combiner for plant height.  Estimates of narrow sense heritability (0.00 – 0.03) for all the traits under study were low which indicated preponderance of non-additive gene action governing these traits. Therefore, inter-mating among selected segregants followed by recombination breeding in an advanced generation might be advocated for improvement of the studied traits under salinity.