title: Latitudinal variation in ambient UV-B radiation is an important determinant of Lolium perenne forage production, quality, and digestibility.
abstract: Few studies to date have considered the responses of agriculturally important forage grasses to UV-B radiation. Yet grasses such as Lolium perenne have a wide current distribution, representing exposure to a significant variation in ambient UV-B. The current study investigated the responses of L. perenne (cv. AberDart) to a simulated latitudinal gradient of UV-B exposure, representing biologically effective UV-B doses at simulated 70, 60, 50, 40, and 30° N latitudes. Aspects of growth, soluble compounds, and digestibility were assessed, and results are discussed in relation to UV-B effects on forage properties and the implications for livestock and bio-ethanol production. Aboveground biomass production was reduced by approximately 12.67% with every 1 kJ m(-2) day(-1) increase in biologically weighted UV-B. As a result, plants grown in the highest UV-B treatment had a total biomass of just 13.7% of controls. Total flavonoids were increased by approximately 76% by all UV-B treatments, while hydroxycinnamic acids increased in proportion to the UV-B dose. Conversely, the digestibility of the aboveground biomass and concentrations of soluble fructans were reduced by UV-B exposure, although soluble sucrose, glucose, and fructose concentrations were unaffected. These results highlight the capacity for UV-B to directly affect forage productivity and chemistry, with negative consequences for digestibility and bioethanol production. Results emphasize the need for future development and distribution of L. perenne varieties to take UV-B irradiance into consideration.
authors.affiliation: Institute of Biological Environmental and Rural Sciences, Aberystwyth University, Ceredigion, SY23 3DA, Wales, UK.
authors.forename: David
authors.initials: D
authors.lastname: Comont
authors.forename: Ana
authors.initials: A
authors.lastname: Winters
authors.forename: Leonardo D
authors.initials: LD
authors.lastname: Gomez
authors.forename: Simon J
authors.initials: SJ
authors.lastname: McQueen-Mason
authors.forename: Dylan
authors.initials: D
authors.lastname: Gwynn-Jones
mesh_terms: D000818:Animals; D056804:Biofuels; D018533:Biomass; D002417:Cattle; D003373:Coumaric Acids / Q000032:analysis; D004063:Digestion; D004307:Dose-Response Relationship, Radiation; D005419:Flavonoids / Q000032:analysis; D005632:Fructose / Q000032:analysis; D005843:Geography; D005947:Glucose / Q000032:analysis; D008129:Lolium / Q000737:chemistry / Q000254:growth & development / Q000528:radiation effects*; D013395:Sucrose / Q000032:analysis; D014466:Ultraviolet Rays
chemical_list: D056804:Biofuels; D003373:Coumaric Acids; D005419:Flavonoids; D005632:Fructose; D013395:Sucrose; D005947:Glucose
keywords: Carbohydrate; digestibility; forage quality; growth; phenolics; ultraviolet-B.