title: Solar Ultraviolet-B Radiation Affects Seedling Emergence, DNA Integrity, Plant Morphology, Growth Rate, and Attractiveness to Herbivore Insects in Datura ferox.
abstract: To study functional relationships between the effects of solar ultraviolet-B radiation (UV-B) on different aspects of the physiology of a wild plant, we carried out exclusion experiments in the field with the summer annual Datura ferox L. Solar UV-B incident over Buenos Aires reduced daytime seedling emergence, inhibited stem elongation and leaf expansion, and tended to reduce biomass accumulation during early growth. However, UV-B had no effect on calculated net assimilation rate. Using a monoclonal antibody specific to the cyclobutane-pyrimidine dimer (CPD), we found that plants receiving full sunlight had more CPDs per unit of DNA than plants shielded from solar UV-B, but the positive correlation between UV-B and CPD burden tended to level off at high (near solar) UV-B levels. At our field site, Datura plants were consumed by leaf beetles (Coleoptera), and the proportion of plants attacked by insects declined with the amount of UV-B received during growth. Field experiments showed that plant exposure to solar UV-B reduced the likelihood of leaf beetle attack by one-half. Our results highlight the complexities associated with scaling plant responses to solar UV-B, because they show: (a) a lack of correspondence between UV-B effects on net assimilation rate and whole-plant growth rate, (b) nonlinear UV-B dose-response curves, and (c) UV-B effects of plant attractiveness to natural herbivores.
authors.affiliation: Ifeva, Departamento de Ecologia, Facultad de Agronomia, Universidad de Buenos Aires, Avenida San Martin 4453, (1417) Buenos Aires, Argentina (C.L.B., A.L.S., M.J.Y.).
authors.forename: C. L.
authors.initials: CL
authors.lastname: Ballare
authors.forename: A. L.
authors.initials: AL
authors.lastname: Scopel
authors.forename: A. E.
authors.initials: AE
authors.lastname: Stapleton
authors.forename: M. J.
authors.initials: MJ
authors.lastname: Yanovsky