Abstract
Pasture grass cultivars grown for forage production in the central region of Saudi Arabia, which is dominated with desert environment, suffer a great deal of heat stress. These growing conditions greatly affect species performance and forage quality. This study was focused on evaluating productivity and forage quality of selected new pasture grass cultivars under heat stress in the central region of Saudi Arabia over a two-year period and investigating the presence of the dehydrin genes as a marker of heat tolerance in grass cultivars. Six grass cultivars were used in this study: two perennial ryegrass (Lolium perenne L.) cultivars (Aries and Quartet), two endophyte-free tall fescue (Festuca arundinacea Schreb.) cultivars (Fawn and K5666v), and two orchardgrass (Dactylis glomerata L.) cultivars (Tekapo and Niva). The results clearly showed variation in the total dry matter yield (DMY) and forage quality among the four grass cultivars. Although Fawn tall fescue showed superiority over all other grass cultivars in surviving high temperatures and producing the highest dry matter yield, the forage quality of this cultivar was the lowest among the cultivars examined. SSR markers for the amplification of dehydrin genes revealed the presence of two dehydrin genes (HVDHN1 and HVDHN9) in grass cultivars Aries, Fawn-tall fescue and Tekapo-orchard grass. Fawn had the homologues dehydrin genes. SSR markers for amplifying dehydrin gene could be valuable in grass breeding programs for selection of desirable DHN alleles under heat stress.