بررسي ياختار ژنتيكي كيفيت و عملكرد علوفه در خانواده هاي تني چچم دايمي LOLIUM PERENE L تحت دو مديريت برداشت حفاظت شده و مشابه چراي دام

Genetic analysis of yield and quality traits in lull sib families of perennial ryegrass (Lolium perenne L.) Under two cutting managements

Breeding perennial ryegrass (Lolium perenne L.) for improved yield and quality traits is an important goal for improving animal performance. The objectives of this research were to determine the extent and nature of genetic variability for three quality traits namely: Digestible organic matter in dry matter (DOMD), water soluble carbohydrates (WSC), crude protein (CP) as well as dry matter yield (DM yield). Near infrared spectroscopy (NIR) were used for estimation of the quality traits. Based on plant maturity, two mid season and late groups of full sib families were developed. The progenies were grown as dense swards under two cutting frequencies (conservation and simulated grazing) over two years. The estimated of broad sense heritability were relatively high for all traits especially in mid season group. Interpretation of these values is restricted because the experimental design(measurement of full sib families variance in dense swards) did not allow estimation of nonadditive genetic variance. Consequently the contribution of such gene effects are unknown. Genotype x Environment interactions (managements and years) were present for dry matter yield and to a lesser extent, for digestibility, water soluble carbohydrates but absent for crude protein. Genetic correlation between traits were consistent. Crude protein was negatively correlated with both dry matter yield and water soluble carbohydrates, while water soluble carbohydrates was positively correlated with dry matter yield and digestibility. The genetic correlation of digestibility with both dry matter yield and crude protein was in general negative. This negative relationship was weak and inconsistent over all cuts.