Abstract Detail

Ecophysiology

Mirza, Humera [1], Arteaga, Marc [1], Santiago, Louis [1].

Using Eco-Physiology to Inform Conservation Outcomes: Photosynthetic Responses to Salinity in Two Endangered Alkali Vernal Pool Species of Atriplex.

Vernal pools are unique seasonal wetland habitats that host many threatened and endangered (sensitive) plant species. Alkali vernal pools, a particular type of vernal pool that occurs on saline soils, pose additional environmental challenges to plant growth. Yet the salt tolerance of many sensitive species that grow on these soils is unknown, making it difficult to predict conservation outcomes. In order to determine the salt tolerance of photosynthesis and growth in Atriplex coronata and Atriplex parishii, plants were grown from seed in a greenhouse where five individuals of each species including Barley were treated with salt solution (Na₂CO₃) and the other five were kept as a control group. When the plants had a few mature leaves, we measured the photosynthetic chlorophyll fluorescence weekly until plants wilted or flowered. We considered three parameters to analyze plant stress level under salinity treatment:  the maximum electron transport rate (ETRmax) and the maximum photochemical efficiency (Fv/Fm) at two light levels:  dark and high light. The data was analyzed by performing t-test (two samples assuming equal variance). There were no significant differences found for ETRmax between the control and experimental groups of either Atriplex species. However, Barley had significantly lower (P<0.05) ETRmax and Fv/Fm in the experimental group, suggesting that it is a less salt tolerant species, common for C3 plants. A. coronata had significantly lower Fv/Fm in darkness in the control group but no difference was at high light. On the other hand, there was no significant difference found in A. parishii for either of the parameters. We present our experimental data in the context of ancillary data on plant community composition and soil chemistry to quantify the biotic and abiotic factors that shape the habitat for these sensitive species. In conclusion, A. coronata appears to be closing stomates leading to photoinhibition, whereas A. parishii has an overall lower photosynthetic rate but suffers less apparent damage, suggesting a tradeoff. In the future, we plan to treat plants with multiple saline solutions and mimic the field site’s abiotic factors, such as inundation and temperature, and also increase the sample size to obtain more accurate results to be compared with the field site data collected over a period of two years. Overall, our study indicates that a finer understanding of stress-induced differences in physiology could help predict conservation outcomes by determining the relative stress resistance of contrasting endangered plant species.

1 - University of California, Riverside, Botany and Plant Sciences, Botany and Plant Sciences department,, Batchelor Hall, University of California, Riversid, Riverside, California, 92521, United States
2 - University of California, Riverside, Botany and Plant Sciences, Botany and Plant Sciences department,, Batchelor Hall, University of California, Riversid, Riverside, California, 92521, United States

Keywords:
ecophysiology
threatened species
endangered species
Atriplex coronata
Atriplex parishii
Chlorophyll fluorescence
salinity tolerence.

Presentation Type: Oral Paper
Number: EPH1006
Abstract ID:700
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize,Physiological Section Best Paper Presentation