Ultraviolet-B Radiation and Plant Competition: Experimental Approaches and Underlying Mechanisms¶

Abstract

Under realistic stratospheric ozone depletion scenarios, ultraviolet-B radiation (280-320 nm) (UV-B) influences plant morphology and plant competitive interactions. Influence of UV-B on plant competition can be studied using a variety of experimental and analytical approaches including inverse yield-density models and allometric, neighborhood or sizestructure analyses that provide links between plant and ecosystem responses. These approaches differ in their abilities to extract information regarding competitive interactions and their morphological underpinnings. Only a limited number of studies have been carried out to investigate UV-B effects on plant competition, and most of these have used the replacement series approach, which has received much criticism. Nonetheless, results to date indicate that slight differences in UV-B-induced morphological responses of species grown within associations can alter canopy structure thereby influencing photosynthetically active radiation (PAR) interception and relative competitive ability. Because the response of individuals of the same species is expected to be uniform, UV-B may influence intraspecific competition less than interspecific competition. Before we can make clear generalizations and predictions concerning the effects of this radiation on plant competition, an understanding is crucial of the mechanisms underlying UV-B-induced shifts in competitive interactions by assessing competition over time.

Influence of R/FR ratio on response of maize, lettuce, and Amaranthus retroflexus L. to UV‐B radiation

“…These morphogenetic and physiological effects of R/FR ratio could trigger processes that determine differential interspecific competitive hierarchies between plants under UV‐B stress. Susceptibility of weed and crop species to UV‐B radiation varies with species (Dai et al, 2004; Wang et al, 2007) and increased UV‐B radiation can change the competitive interactions between a crop and weeds (Furness et al, 2005a, 2005b). The present study suggests that the effects of UV‐B radiation are not altered by changes in R/FR ratio.…”

Growth and allocation in seedlings of three shade intolerant species: the role of biotic and abiotic factors

“…However, UV-C does not reach the Earth's surface and much of the UV-B is absorbed by stratospheric ozone. Plant responses to UV radiation include reduced plant height, stem length elongation, leaf area, leaf elongation, root length, rhizome internode elongation, and changes in the number of leaves, branches or tillers(Furness et al 2005;Caldwell et al 2007). Changes in plant morphology are often accompanied by modification in the partitioning of biomass).…”