PS 27-128
Seed source geography influences phenology and gas exchange rates of Pityopsis graminifolia populations
The limited availability of native plant materials challenges restoration success across a wide spectrum of natural communities. Although plant materials are being produced, the provenance of commercial varieties is limited, and materials are being purchased for use in widespread locations to which they may not be well-adapted. There is a need to understand relationships between seed source locations and plant performance. We have initiated common garden studies of herbaceous perennials of the longleaf pine ecosystem. The study includes grasses, composites, and legumes. Here we report results from comparing populations of Pityopsis graminifolia produced from seed collected in 12 populations from the middle and southern Atlantic coastal plain (MAC, SAC) ecoregions and one lot from a commercial source. We sowed seed in Fafard 3B media in cells measuring 2.5 cm diameter x 15 cm deep and germinated them under mist. Seedlings were transferred to a hand-watering regime to maintain soil at field capacity and were fertilized at week 2. At approximately 15 weeks, we measured morphological characteristics including leaf number and size, presence of inflorescences, and number of basal shoots, and measured net photosynthesis using a CIRAS-2 portable system. We used ANOVA to test for an ecoregion effect on all metrics.
Results/Conclusions
We found SAC populations were phenologically advanced, with significantly (P<.05) more plants having flowered and produced more basal shoots than the MAC populations. We found on average that MAC plants photosynthesized at higher rates than SAC populations. Early growth of southern populations may put them at a disadvantage in more northern sites where late frosts may injure tender new growth; however, southern types may be better adapted to maintaining favorable carbon balances under higher temperatures. This study will continue as P. graminifolia and 5 additional species are out-planted to three common garden locations for continued evaluation.