Meeting Abstract
Plants have mechanisms to sense dangerous ultraviolet radiation and regulate their responses to changes in their light environment. In particular, plants exposed to UV-B (280 to 315 nm) display unique responses such as inhibited growth and production of UV-protecting pigments. These responses are the can be either global or tissue specific. Little bluestem (Schizachyrium scoparium) were sampled at a field site in Travis County, Texas. We chose 3 minimally invasive methods commonly used to measure plant responses to UV stress: UV absorbance spectra taken from leaf extract pigments, reflectance spectrophotometry of leaves, and leaf chlorophyll and flavonoid content. Results indicate that individual plants maintain different protections from UV radiation including changes in leaf structure and composition from bunch to bunch, even within the same field site (120 m2). For instance, there were significant differences between two bunches four meters apart for absorbance, reflectance, chlorophyll, and flavonoids. The consequence of this variation can be seen by comparing a result to the outcome of modifying the UV environment: the 67.9% decrease in absorbance at 300nm between two untreated bunches eight meters apart is comparable to the 69.5% decrease in absorbance in one bunch after one week’s time under a UV-B excluding cellulose acetate filter. However, across 10 bunches many pairs showed no differences or differences in only some parameters. Overall, these results inform the design of further research into plant responses to UV-B radiation by demonstrating the need for large samples including many individuals to ensure that the results are actually a response to the treatment and not natural variation between individual plants.
