Presentation Title

Decline in Photosynthesis and Stomatal Conductance by Goldback Ferns During Seasonal Desiccation in the Santa Monica Mountains

Faculty Mentor

Stephen Davis

Start Date

17-11-2018 12:30 PM

End Date

17-11-2018 2:30 PM

Location

HARBESON 28

Session

POSTER 2

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

Many species of ferns in the Santa Monica Mountains of southern California possess physiological mechanisms that allow them to withstand protracted summer drought. Two of these species, Pentagramma triangularis (gold back fern) and Pellaea andromedifolia (coffee fern), utilize desiccation tolerance as a drought survival mechanism. We understand few details of this survival mechanism. We chose to examine maximum photosynthetic performance and stomatal controls of leaf water loss throughout the desiccation process of Pentagramma triangularis, growing in its natural setting, in Newton Canyon of the Santa Monica Mountains, 20 km from Pepperdine University in Malibu. We used a field portable gas-exchange system (Li-Cor 6800) to measure dark respiration (Rd), maximum photosynthesis under saturating light (Amax), stomatal conductance to water vapor diffusion (Gs), as well as chlorophyll fluorescence parameters in the dark (Fv/Fm) and light throughout the summer as soil moisture was depleted and ferns desiccated to air dryness (<-30MPa). We found that stomatal aperture decreases markedly as P. triangularis approaches deep desiccation while photosynthetic rates as well as fluorescence parameters decreases to zero. These results support our initial hypothesis that the desiccation process of Pentagramma triangularis utilizes stomatal control to the very entry into deep desiccation.

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Nov 17th, 12:30 PM Nov 17th, 2:30 PM

Decline in Photosynthesis and Stomatal Conductance by Goldback Ferns During Seasonal Desiccation in the Santa Monica Mountains

HARBESON 28

Many species of ferns in the Santa Monica Mountains of southern California possess physiological mechanisms that allow them to withstand protracted summer drought. Two of these species, Pentagramma triangularis (gold back fern) and Pellaea andromedifolia (coffee fern), utilize desiccation tolerance as a drought survival mechanism. We understand few details of this survival mechanism. We chose to examine maximum photosynthetic performance and stomatal controls of leaf water loss throughout the desiccation process of Pentagramma triangularis, growing in its natural setting, in Newton Canyon of the Santa Monica Mountains, 20 km from Pepperdine University in Malibu. We used a field portable gas-exchange system (Li-Cor 6800) to measure dark respiration (Rd), maximum photosynthesis under saturating light (Amax), stomatal conductance to water vapor diffusion (Gs), as well as chlorophyll fluorescence parameters in the dark (Fv/Fm) and light throughout the summer as soil moisture was depleted and ferns desiccated to air dryness (<-30MPa). We found that stomatal aperture decreases markedly as P. triangularis approaches deep desiccation while photosynthetic rates as well as fluorescence parameters decreases to zero. These results support our initial hypothesis that the desiccation process of Pentagramma triangularis utilizes stomatal control to the very entry into deep desiccation.