تجزيه ژنتيكي عملكرد و كيفيت علوفه در والدين و خانواده هاي ناتني FASTUCA ARUNDINACEA

Genetic analysis of yield and forage quality of parents and half sib families of tall fescue (Festuca arundinacea schreb.)

In order to estimate heritability, prediction of genetic gain per cycle of selection, and relationships among forage yield and quality traits of tall fescues (Festuca arundinacea Schreb.), a polycross nursery containing twenty genotypes was established. At the harvest time, seeds of each genotype were collected. Both seed of half sib families and their clonally propagated parents were grown as spaced plants using a completely randomized design with four replications in Alborz Research Center, Karaj, Iran during 2001-2003. The data were collected and analyzed for dry matter yield, ear emergence date, plant height and plant diameter, water soluble carbohydrate (WSC), crude protein (CP) dry matter digestibility (DMD), crude fiber (CF), acid detergent fiber (ADF) and total ash over two years. The estimates of broad sense heritability (h2b) were average to high (0.44 to 0.92) for dry matter yield and morphological traits indicating the presence of genetic variation for all of them. Narrow sense heritabilities (h2n and h2op) were average to high values for dry matter yield and heading date and lower for plant height and plant diameter, indicating the importance of additive genetic variance in controlling of dry matter yield and heading date and the importance of non-additive genetic variance in controlling of plant height and plant diameter. For all of quality traits the estimates of h2b were average to high (h2b=0.31 to 0.68). The h2n and h2op estimated values were low for WSC and DMD and the same values as h2b for other quality traits indicating the presence of non additive genetic variance for WSC and DMD and additive genetic variance in controlling of other quality traits. Predicted genetic gains per cycle of phenotypic selection for dry matter yield and heading date were 20 and 14 percent improvement from the mean of population. The genetic correlation between WSC and DMD were positively significant, while the relationships between CP and WSC were negatively significant. The genetic correlation between DMD and CP were inconsistent. Dry matter yield had a negative and non significant relationships with DMD and WSC, but the genetic correlation between dry matter yield and CP were strongly negative.