Savage, Jessica , Cavender-Bares, Jeannine , Verhoeven, Amy .
Variation in the photochemistry of six co-occurring willow (Salix) species and their nonphotochemical energy dissipation during an experimental dry-down.
In Minnesota, many willow (Salix) species co-occur within the same landscape, and even the same wetland. Several of these species, though closely related, demonstrate different physiological responses to drought. While some experience rapid senescence, indicating a drought “avoidance” strategy, others maintain their leaves at more negative water potentials, indicating a drought “tolerance” strategy. It was hypothesized that these differences in leaf senescence rates would coincide with different photoprotective strategies in the species. In order to investigate the extent of nonphotochemical energy dissipation during dry-down, we conducted a controlled greenhouse drought experiment on six sympatric willow species from Minnesota. Before the onset of the drought and twice during the progression of the drought, chlorophyll fluorescence was measured, and leaf punches were collected for xanthophyll pigment analysis with HPLC. All species experienced a decrease in photochemical quenching and an increase in non-photochemical quenching during the drought. In most species, as chlorophyll levels decreased, the total xanthophyll pool and the proportion of zeaxanthin and antheraxanthin increased. By late in the drought, species began to demonstrate differences in their dark-adapted quantum yield and their total xanthophyll pool sizes. This experiment demonstrated that these closely related, co-occurring species not only differ in their drought-induced leaf senescence but also in their photoprotective ability.
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1 - University of Minnesota, 100 Ecology Bldg, 1987 Upper Buford Circle, St Paul, Minnesota, 55108, USA
2 - University of St. Thomas, Department of Biology, 2115 Summit Avenue, Saint Paul, MN, 55105, USA
nonphotochemical heat dissipation
leaf senescence .
Presentation Type: Oral Paper:Papers for Sections
Location: Williford C/Hilton
Date: Wednesday, July 11th, 2007
Time: 3:45 PM