Abstract:

In order to clarify the phenotypic and genetic variation differences of F₁ and backcross hybrid progenies in oat （Avena sativa）， crosses were made in this study between four oat varieties： Forage （F709）， 709 （709F）， Molass （ML2） and Longyan No. 2 （L2M）. Molecular identification of hybrid F₁ plants was conducted by simple sequence repeat （SSR） and their phenotypic differences were compared. The genetic variation and diversity of the F₂ generation were also analyzed. It was found that 32 from 37 （86.5%） of F₁ plants were identified as true hybrids based on SSR. True hybrid rates of up to 88.9% were obtained for the Forage and 709 crosses， and rates of up to 84.2% were obtained for Molass and Longyan No.2. The cross mode significantly affected hybrid phenotype. The flag leaf width of F709-F₁ was 19.4% narrower than that of 709F-F₁. The grain number of the main panicle of ML2-F₁ was 12.2% less than that of L2M-F₁. The genetic variation of the F₂ population was remarkable. Significant differences were observed in the F₂ genetic variation coefficient （G_cv）， generalized heritability （H_b） and relative genetic progress （ΔG_t） of the same trait in F₁ and backcrosses. Among the F₂ population， plant height had the lowest G_cv （4.50%-10.27%） and higher H_b （33.12%-85.41%） while tiller number and effective tiller number had the greatest relative genetic progress. The H_b of peduncle length of the F₂ population from Forage and 709 was the lowest （14.13% for the F₁ cross and 23.81% for the backcross）， with the least relative genetic progress. Significant G_cv and H_b differences between the F₁ and backcrosses， were observed for grain number of the main panicle with values of 7.09% and 22.54%， respectively in F709-F₂， and 19.03% and 66.01% in the backcross._{The leaf number of the F2 population from Molass and Longyan No.2 had the highest Hb （99.53%）， indicating little environmental effect. The Hb of flag leaf width of ML2-F2 was 9.07%， and ΔGt was 2.79， while in L2M-F2， Hb was 30.23% and ΔGt was 9.77. Ten polymorphic SSR primers resulted in 73.5% polymorphism rate in the F2 population. Actual heterozygosity （0.35-0.99） was much higher than the expected heterozygosity. The Nei’s gene polymorphism and Shannon index were 0.29-0.50 and 0.53-0.71， respectively， indicating an obvious segregation and greater variation with great selection potential.}

Key words: oats, hybrid identification, phenotypic traits, genetic variation