Theme 1: Grassland Ecology
Description
Annual ryegrass [Lolium perenne L. spp. multiflorum (Lam.) Husnot] is a high-quality forage utilized heavily in the Southeast for pasture and grazing. Gray Leaf Spot (Pyricularia oryzae) is a fungal pathogen that infects gramineous species and is a common problem in perennial and annual ryegrass stands. This study was designed to screen for resistance to P. oryzae in the annual ryegrass cultivar Vertyl (PI 619473, FRA) and a heat-tolerant germplasm (HTARG5) derived from Marshall (PI 600770, USA) with intent to use recurrent phenotypic selection to crossbreed the two accessions. Marshall was also included as a susceptible reference cultivar. Two experiments were conducted, the first with 100 plants screened at 12-wk old and the second with 180 plants screened at 6-wk old. Plants were spray inoculated with a spore solution of 1 x 105 conidia mL-1 and incubated for 72h at 30:25°C (D:N), ≥85% RH. Percentage disease severity (DS) was assessed 3wk post inoculation by dividing the number of diseased leaves by the total number of leaves per plant. Germplasm accession was used as a main effect and was significant in both Exp. 1 (P=0.0341) and Exp. 2 (P=0.0036). For Exp. 1, mean DS was significantly greater in heat-tolerant germplasm (29.3) than Vertyl (19.4) (LSD = 8.1). For Exp. 2, mean DS for Vertyl, Marshall, and the heat-tolerant germplasm were 44.82, 61.02, and 62.55, respectively. Disease severity in Vertyl was significantly lower (LSD = 12.1) than both Marshall and the heat- tolerant germplasm. Mortality was also recorded, however, there was no significant difference between accessions for either experiment. These results confirm that Vertyl has significantly greater resistance to gray leaf spot than Marshall and can be a quality candidate for selection breeding.
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Screening Annual Ryegrass for Increased Tolerance to Blast (Pyricularia oryzae)
Annual ryegrass [Lolium perenne L. spp. multiflorum (Lam.) Husnot] is a high-quality forage utilized heavily in the Southeast for pasture and grazing. Gray Leaf Spot (Pyricularia oryzae) is a fungal pathogen that infects gramineous species and is a common problem in perennial and annual ryegrass stands. This study was designed to screen for resistance to P. oryzae in the annual ryegrass cultivar Vertyl (PI 619473, FRA) and a heat-tolerant germplasm (HTARG5) derived from Marshall (PI 600770, USA) with intent to use recurrent phenotypic selection to crossbreed the two accessions. Marshall was also included as a susceptible reference cultivar. Two experiments were conducted, the first with 100 plants screened at 12-wk old and the second with 180 plants screened at 6-wk old. Plants were spray inoculated with a spore solution of 1 x 105 conidia mL-1 and incubated for 72h at 30:25°C (D:N), ≥85% RH. Percentage disease severity (DS) was assessed 3wk post inoculation by dividing the number of diseased leaves by the total number of leaves per plant. Germplasm accession was used as a main effect and was significant in both Exp. 1 (P=0.0341) and Exp. 2 (P=0.0036). For Exp. 1, mean DS was significantly greater in heat-tolerant germplasm (29.3) than Vertyl (19.4) (LSD = 8.1). For Exp. 2, mean DS for Vertyl, Marshall, and the heat-tolerant germplasm were 44.82, 61.02, and 62.55, respectively. Disease severity in Vertyl was significantly lower (LSD = 12.1) than both Marshall and the heat- tolerant germplasm. Mortality was also recorded, however, there was no significant difference between accessions for either experiment. These results confirm that Vertyl has significantly greater resistance to gray leaf spot than Marshall and can be a quality candidate for selection breeding.
