Growth and physiological responses of an invasive alien species, Silene noctiflora, during two developmental stages to four levels of ultraviolet-B radiation

Few studies have considered the effects of ultraviolet-B (UVB) radiation during different developmental stages of plants, especially on invasive alien species. We studied growth and physiological responses of night-flowering catchfly (Silene noctiflora) to UVB radiation during 2 developmental stages. Silene noctiflora plants were grown under biologically effective UVB (UVBBE) radiation of 0, 4, 8, and 16 kJ.m(-2).d(-1) in controlled-environment growth chambers. Growth and physiological parameters of plants were measured during vegetative and reproductive stages. In general, enhanced UVB radiation reduced stem height and diameter, leaf area, and total dry matter. It also decreased leaf weight ratio, leaf area ratio, stomatal number, net CO2 assimilation, water use efficiency, and chlorophyll concentration but increased specific leaf weight, epidermal cell size, transpiration, UV-absorbing compounds, and epicuticular wax. Plants were taller and had higher chlorophyll, UV-absorbing compounds, and wax but lower ethylene evolution in the reproductive stage than in the vegetative stage. Overall, S. noctiflora plants were damaged by a four-fold increase of UVB radiation, as was apparent from reduced total seed yield. They acclimated under ambient UVB and a two-fold increase of UVB in their reproductive stage. These results mean that this plant may remain an invasive species under increased UVB radiation.