General combining ability of half-sib families of tall fescue (Festuca arundinaceum Schreb)

During early stages of breeding programs for large populations of forage plants، general combining ability (GCA) can be used to select superior families for development of a synthetic variety. Tall fescue is one of fescue species that are economically important and widely used as a forage grass. Tall fescue is self-incompatible and wind cross pollinated. This study was conducted to evaluate general combining ability of 25 polycross families of the species during 2012 and 2013 at a research station in Isfahan، in center part of Iran. Number of days to pollination، plant height، number of fertile tiller، length، and width of flag leaf، spike length، seed and forage yield of the families were evaluated. For number of days to pollination، genotype 13 and genotype 23 had the most and the least GCA (6. 24 and -7. 76)، respectively. For fresh forage yield and dry forage yield، genotypes numbered 15، 18 and 19، 20، 23 and 24 had the most GCA. The six mentioned genotypes also had the most values for seed yield. It seems that crosses between the genotypes may produce synthetic varieties with high yield capacity. Cluster analysis grouped the families in four clusters. Analysis of variance showed that the third group had the highest mean for forage yield. Variation in GCA values was observed in most of the studied traits. Simultaneous studies of cluster analysis and GCA of the genotypes can help to find the best parental genotypes to produce synthetic varieties in future breeding programs.