Heritability Estimates of Zoysiagrass (Zoysia spp) for Morphological Variation and Rust Response.

Zoysiagrass (Zoysia spp) is a warm season turfgrass used for golf courses, home lawns and recreation fields. The most utilized species are Zoysia matrella and Zoysia japonica with differing leaf textures, growth habits and seed heads. Zoysia japonica has medium-coarse leaf texture, upright growth and longer seed heads, while Z. matrella has a finer leaf texture, more compact growth habit and shorter seed heads.  Hybrids between these species are viable and have been evaluated for improved tolerance to biotic and abiotic stress factors. Heritability values have been estimated in zoysiagrass for coverage, density, quality, genetic color, fall dormancy, seed head density, and limited disease and nematode resistance. Heritability and segregation of other traits have not been estimated for populations of Z. matrella and Z. japonica.  Large patch disease development was compared on 50 germplasm lines that were inoculated and incubated in controlled walk-in chamber. Nineteen lines with different leaf textures and disease responses were used to develop a parental population. The narrow sense heritability of stem and leaf color, leaf texture, growth habit, raceme length and number, floret color, and rust response were estimated in progeny from six families.Variation was observed for all traits.  Heritability estimates were calculated using ASReml software, version 3.0. High heritability was observed for leaf width (0.61); indicating that this trait in this population is mainly influenced by genetic effects. Moderate heritability estimates were obtained for stem color (0.39), flowering initiation (0.36) and rust response (0.36). Relatively low heritability values were obtained for leaf color (0.25), growth habit (0.23), raceme length (0.14) and floret color (0.10), indicating that these traits in this population are more influenced by environmental factors. Overall these results indicate that the traits are under genetic control and that improvements can be obtained through hybridization and selection of desirable individuals.