Selection for Stem Rust Resistance in Tall Fescue and Its Correlated Response with Seed Yield

et al., 1981) and timothy (Phleum pratense L.; Braverman, 1966; Nielson and Dickson, 1958). In addition, Genetic resistance to stem rust (caused by Puccinia graminis several cultivars of perennial ryegrass (Lolium perenne Pers.:Pers. subsp. graminicola Z. Urban) could reduce the need for fungicides to control the disease in tall fescue [Lolium arundinaceum L.) with reduced susceptibility to stem rust, developed (Schreb.) Darbysh. ( Festuca arundinacea subsp. arundinacea)] through selection in the field after natural inoculation, grown for seed. Two populations from 14 resistant forage-type plants have been released (Robinson et al., 1988; Meyer et al., (F) and 20 turf-types (T) were developed using polycross (PX) and 1989; Meyer and Rose-Fricker, 1990). These cultivars, open pollination (OP) progenies. A two-stage controlled environment however, rapidly lost resistance as generations of seed inoculation was used for screening and selection for two cycles. Direct production increased most likely because there was inselection response was determined after two artificial inoculations in a controlled environment. Indirect selection response for seed yield sufficient number of plants with resistance in base popuwas measured, using the same plants as the direct selection study, in lations or the field screening technique was not adethe field using natural inoculation for 4 yr. Plants with resistant reacquate, and because the host-pathogen interaction for tion, based on pustule type, increased from 5 to 54% in the F popularyegrass is poorly understood. tion and from 6 to 50% in the T after two cycles of PX selection and Welty and Barker (1993) surveyed 20 cultivars of tall from 5 to 63%, and from 6 to 50% in the F and T populations, fescue for resistance to stem rust. Overall, none of the respectively, after one cycle of OP followed by one cycle of PX cultivars per se were judged resistant, but some cultivars selection. In each selection scheme, the largest increase came from the first PX cycle. Seed yield of tall fescue with improved stem rust had plants with a resistant reaction from both artificial resistance was higher than for susceptible populations or cultivars inoculation in the greenhouse and natural inoculation with heavy stem rust presence (1998), but yields were similar with no in the field. The resistant plants were saved and used rust pressure (1999). These results indicate that seed yields in tall as the base populations in a selection program to imfescue can be maintained using genetic resistance to stem rust suffiprove stem rust resistance. This study reports the direct cient to slow or eliminate disease epidemic development. selection responses from two cycles of recurrent selection in controlled environment screening and the indirect responses on seed yield of tall fescue when grown T fescue is used for both forage and turf in temfor four years in the field. perate regions of the world. More than 60 000 ha of tall fescue are grown for seed in Oregon and it ranks second in hectarage among grasses grown for seed in MATERIALS AND METHODS the Willamette Valley of Oregon (Young, 2001). Stem Source plants for this study were selected from among 1400 rust was first reported in tall fescue seed production plants in a nursery established in 1990 containing 70 plants fields in Oregon in 1987 (Welty and Mellbye, 1989), and from each of 20 cultivars (Welty and Barker, 1993). Selection the economic impact of the disease has increased in criterion, as described by Welty and Barker (1993), was freerecent years. Fungicides are commonly used to control dom from stem rust symptoms after two inoculations on seedthe disease in grass seed production (Pscheidt, 1996). lings in a controlled environment chamber and two scoring Genetic host resistance to the disease, however, would periods (July 11 and 23) in 1990 after plants were transplanted provide a more environmentally sound approach for to the field. Thirty-four plants had resistant reactions in concontrol. Incorporation of host resistance has been suctrolled environment inoculations and were scored as resistant cessful in controlling rusts of wheat (Triticum aestivum in field plots. These plants were divided into two populations L.; Dyck and Kerber, 1985), barley (Hordeum vulgare based on the intended use of the cultivar from which they L.; Cotter and Levine, 1932), and maize (Zea mays L.; came. Twenty plants were placed in a turf-type population Hooker, 1985). (T) with plants coming from the cultivars Arid (6), Mesa (6), Thoroughbred (4), Finelawn I (2), Finelawn 5GL (1), and While genetic host resistance to stem rust in tall fescue Adventure (1); fourteen plants in a forage-type population had not been reported prior to our studies, it had been (F) coming from the cultivars Kentucky 31 (10) and Forager found in Kentucky bluegrass (Poa pratensis L.; Britton (3); and one plant from ‘Johnstone’, a tall fescue backcross and Butler, 1965; Elliott, 1963; Johnson-Cicalese et al., derivative from an annual ryegrass (Lolium multiflorum 1983; Pfleger, 1973; Rogerson and King, 1954; Watkins Lam.) tall fescue hybrid. USDA-ARS National Forage Seed Production Research Center, 3450 SW Campus Way, Corvallis, OR 97331. Joint contribution of the Abbreviations: AIT, average infection type; C1, cycle 1; C2, cycle 2; USDA-ARS and the Oregon Agric. Exp. Station. Contribution No. source population; F, forage-type population; PX, polycross; OP, open 11861 by the Oregon Agric. Exp. Stn., Corvallis, OR. Received 15 pollinated selection; OP-PXr, OP followed by PX selection for resisJan. 2002. *Corresponding author ([email protected]). tance; OP-PXs, OP followed by PX selection for susceptibility; SSE, super susceptible check; T, turf-type population. Published in Crop Sci. 43:75–79 (2003).