The genus Festuca L. is one of the largest in the family Gramineae whose members are widely adapted to a variety of ecogeographical regions (Yamada 2011). Festuca is comprised of some 450 species (Clayton and Renvoize 1986) that range from diploid (2n=2x=14) to dodecaploid (2n=12x=84) in chromosome number (Smarda and Stancik 2006). Tall fescue is the most economically important forage and turf-grass species in the genus and is grown throughout temperate regions of the world (Saha et al. 2005). Tall fescue is mostly used as a turfgrass in many areas of the world, including parts of North and South America, Europe, and in cooler regions of Asia, Africa, Australia, and New Zealand. The primary reason that Tall fescue does well in cold, arid, and semiarid regions is its ability to survive under drought conditions compared to other cool-season turfgrass species (Fry and Huang 2004). According to Rechinger (Rechinger 1970), Tall fescue is one of the perennial grasses that are endemic to cold and dry regions of central, northeastern, and northwestern of Iran. Cool-season grass species are typically intolerant of drought during the germination stage, thus making turf establishment difficult under conditions of low soil moisture. Seed germination usually requires supplemental irrigation (Christians 2004). Investigation of emergence and seedling performance under conditions of low soil moisture is an efficient process to screen genotypes of cool-season grassesfor drought resistance (Gazanchian et al. 2006). Plant growth parameters such as germination and subsequent seedling growth can be inhibited by soil water deficits (Hsiao and Xu 2000; Mut and Aka 2010). Traits associated with emergence and seedling establishment of cool-season grasses under water stress conditions are rapid germination, enhanced seedling vigor, larger seed size (Mut and Aka 2010), early root initiation, and rapid root extension (Johnson and Asay 1993). Berg and Zeng 2006 and Roohollahiet al. 2009 found that leaf growth decreased and root length increased slightly when exposured to drought stress. Drought plays a significant role in determining emergence rates and seedling development (Berg and Zeng 2006).
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