Abstract Detail

Physiology

Grinovich, Brandon Reed [1], Davis, Stephen [2], Holmlund, Helen [3].

Photosynthetic Performance of an Evergreen Fern (Dryopteris arguta) during Protracted Drought in California.

Over the last six years, chronic drought has affected the entirety of California’s natural landscapes, causing significant dieback in many native species, including those found in evergreen chaparral shrub communities. Seasonal evergreen fern species also grow in the understory of the chaparral shrubs, but the impact of chronic drought on such species is poorly understood. Previous work has shown that the Coastal Wood Fern (Dryopteris arguta) shows the highest tissue dehydration tolerance of eight chaparral fern species, withstanding leaf water potentials below -8 MPa. This remarkable ability to withstand dehydration even in unusually harsh conditions makes D. arguta an interesting subject for investigating fern mechanisms for dehydration tolerance and survival during chronic drought. We hypothesized that, contrary to the strategies of other chaparral fern species, Dryopteris arguta would maintain photosynthetic activity even when dehydrated to low water potentials. In order to learn more about the survival mechanisms of D. arguta, we used an Li-6800 gas-exchange system to construct A/C_i curves. We also used a Scholander-Hammel pressure chamber to measure water status throughout a summer dehydration process from May through July 2018. During the dry-down period, leaf water potentials decreased from -2 MPa to -4 MPa. Photosynthetic parameters likewise decreased by approximately a factor of two (maximum carboxylation rate, Vcmax; maximum electron transport rate, Jmax), matching the degree of dehydration. These results show that leaf tissue dehydration to -4 MPa reduces, but does not halt, the photosynthetic activity of D. arguta during summer dry periods and explains, in part, the benefits of an evergreen habit. Future research may explore the effects of greater tissue dehydration on the photosynthetic rate of this evergreen, dehydration-tolerant fern growing in dryland chaparral communities.

1 - Pepperdine University
2 - Pepperdine University, NATURAL SCIENCE DIV, 24255 Pacific Coast Highway, Malibu, CA, 90263, United States
3 - University of CA, Santa Cruz, Ecology and Evolutionary Biology, 130 McAllister Way, Santa Cruz, CA, 95060, USA

Keywords:
drought
Dryopteris
Chaparral
fern.

Presentation Type: Poster
Session: P, Physiology Posters
Location: Arizona Ballroom/Starr Pass
Date: Monday, July 29th, 2019
Time: 5:30 PM This poster will be presented at 6:15 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PPS004
Abstract ID:838
Candidate for Awards:Physiological Section Best poster presentation,Physiological Section Physiological Section Li-COR Prize