Diurnal patterns of photosynthesis, chlorophyll fluorescence, and PRI to evaluate water stress in the invasive species, Elaeagnus umbellata Thunb.

Abstract

Photosynthesis, chlorophyll fluorescence, and hyperspectral reflectance were used to evaluate diurnal changes of Elaeagnus umbellata to quantify physiological responses of the invasive species during times of stress. Field measurements showed that E. umbellata is able to maintain higher levels of photosynthesis relative to nearby Quercus alba plants, with less water loss. Plants subjected to progressive drought were able to recover photosynthesis one day following re-watering. Laboratory and field measurements revealed decreasing DF/F 0 m values in response to drought stress, with little corresponding decrease in photochemical reflectance index values. This research supports the view that xanthophyll cycle dissipation is not the photoprotective mechanism at work for Elaeagnus species under water stress. Elaeagnus umbellata maintains photosynthetic carbon assimilation even under drought conditions, in part, due to chemical dissipation of excess light, and in part because of morphological features that limit excess radiation while maximizing photosynthetic carbon gain. These characteristics may contribute to the invasive success of E. umbellata.

Affecting Factors and Recent Improvements of the Photochemical Reflectance Index (PRI) for Remotely Sensing Foliar, Canopy and Ecosystemic Radiation-Use Efficiencies

“…Canopy PRI values were higher on cloudy days with low irradiance than on sunny days [130], and were correlated most strongly with RUE under clear or slightly overcast skies [123]. For some vegetation such as Elaeagnus umbellate, a drought-tolerant invasive species, PRI decreased slightly during water stress because of the plant's special physiological and morphological characteristics [122].…”

“…Changes in pigment concentrations due to water stress, however, could also potentially affect the seasonal variability of PRI [118][119][120], but these changes varied between species such as Umbilicaria arctica and U. hyperborean [118]. PRI clearly differentiated between normal and stressed holm oaks but was not very informative under a severe drought [121], and could generally detect the physiological status of water-stressed plants but was not useful for the drought-tolerant species Elaeagnus umbellate [122].…”

Influence of foliar application of silicon on chlorophyll fluorescence, photosynthetic pigments, and growth in water-stressed wheat cultivars differing in drought tolerance

“…Although drought stress inhibits a variety of physiological processes in plants, its most significant inhibitory effect can be observed on photosynthesis (Chen et al, 2011). In particular, PSII photochemistry has been shown to be sensitive to water deficit conditions (Baker and Rosenqvist, 2004;Naumann et al, 2010). For example, water deficit conditions considerably damage the oxygen evolving complex of PSII and the PSII reaction centers in most plants (Naumann et al, 2010).…”

“…In particular, PSII photochemistry has been shown to be sensitive to water deficit conditions (Baker and Rosenqvist, 2004;Naumann et al, 2010). For example, water deficit conditions considerably damage the oxygen evolving complex of PSII and the PSII reaction centers in most plants (Naumann et al, 2010). Such drought-induced damage to PSII reaction centers has been ascribed to the degradation of structural proteins (Ohashi et al, 2006).…”

Photosynthetic characterization of three dominant plant species in the saline–alkaline soil of the Yellow River Delta, China

“…Photosynthesis is an essential process for developing the simulation models that enable estimating plant growth and productivity. Higher photosynthetic rates reflect the potential of a species to accumulate more biomass (Naumann et al 2010).…”