This study investigated four different mechanisms of growth performance of a native chaparral species, Venegasia carpesioides, and a weedy species, Nicotiana glauca. The research group hypothesized that one or more of the following variables would be higher for the weedy species than the native species: photosynthetic rate, conductance, fluorescence, and electron transport rate (ETR). This hypothesis was formulated in order to provide a plausible explanation for why weedy species often outcompete native species when grown in proximity to each other, especially in a chaparral environment experiencing drought conditions. This hypothesis was tested by obtaining two groups of each species and testing these variables using a LI-6400XT gas exchange system. The results obtained showed that the photosynthetic rate, fluorescence, and ETR were higher for the native plant species than for the weedy plant species; a Student t-Test showing statistically significant differences between those values, while there was no statistically significant difference for conductance between the two species. Using Nicotiana glauca and Venegasia carpesioides as model specimens, the results did not support our hypothesis that weedy plant species outcompete native plant species by one of the four mechanistic variables measured.
Blair, Emily J.; Coffman, Zach G.; and Jones, Celina Y., "Measuring Performance of a Weedy Species (Nicotania glauca) vs. a Native Species (Venegasia Carpesioides) on the Pepperdine Campus" (2014). Pepperdine University, All Undergraduate Student Research. Paper 110.