Abstract

Our experiment aimed at assessing the influence of ultraviolet-B (UV-B) radiation on the growth and colonization of roots of two invasive rangeland species: houndstongue (Cynoglossum officinale L.) and downy brome (Bromus tectorum L.) with arbuscular mycorrhizal fungi (AMF). As a result, after 13 weeks of growth in the presence of 8 kJ*m^-2 UV-B radiation (estimated as 23% of ozone layer depletion), a significant reduction of houndstongue’s lamina length, leaf area, shoot and root dry mass was noted. As for downy brome, only the stem length and shoot dry mass were negatively affected. Nevertheless, the intensity of UV-B radiation downy brome developed a similar number of inflorescence. For both species in the presence of elevated UV-B_BE radiation, a significant reduction in the AMF colonization was noted, especially for hyphae and arbuscules. In conclusion, the elevated UV-B radiation may affect the performance of both weeds and relate with their competition abilities.

Key words: Arbuscule, downy brome, growth, houndstongue, hyphae.