High C3 photosynthetic capacity and high intrinsic water use efficiency underlies the high productivity of the bioenergy grass Arundo donax

Abstract

Arundo donax has attracted interest as a potential bioenergy crop due to a high apparent productivity. It uses C3 photosynthesis yet appears competitive with C4 grass biomass feedstock’s and grows in warm conditions where C4 species might be expected to be that productive. Despite this there has been no systematic study of leaf photosynthetic properties. This study determines photosynthetic and photorespiratory parameters for leaves in a natural stand of A. donax growing in southern Portugal. We hypothesise that A. donax has a high photosynthetic potential in high and low light, stomatal limitation to be small and intrinsic water use efficiency unusually low. High photosynthetic rates in A. donax resulted from a high capacity for both maximum Rubisco (Vc,max 117 μmol CO2 m−2 s−1) and ribulose-1:5-bisphosphate limited carboxylation rate (Jmax 213 μmol CO2 m−2 s−1) under light-saturated conditions. Maximum quantum yield for light-limited CO2 assimilation was also high relative to other C3 species. Photorespiratory losses were similar to other C3 species under the conditions of measurement (25%), while stomatal limitation was high (0.25) resulting in a high intrinsic water use efficiency. Overall the photosynthetic capacity of A. donax is high compared to other C3 species, and comparable to C4 bioenergy grasses.

Agronomic and physiological response of giant reed (Arundo donax L.) to soil salinity

“…The physiological performances of potted giant reed in the control treatment were comparable with those reported in other experiments made with plants grown either in pots or in open field conditions: the mean seasonal stomatal conductance (0.298 mol m -2 s -1 ) and assimilation rates (21.4 μmol m -2 s -1 ) in control plants were similar to those reported by Sanchez et al (2015) in potted plants grown in greenhouse, by Cosentino et al (2016) in two-year old fully irrigated plants in open field conditions, and by Webster et al (2016) in natural stands. We are not aware of research reporting leaf water potential of giant reed under salt stress conditions; however, Cosentino et al (2016), in plant irrigated with 50% ETM, and Mann et al (2013), under mild drought (9% soil moisture, soil matric potential, Ψm = -0.5 MPa), reported leaf water potential values proximal to the values (-2.08 MPa) measured in our S3 treatment.…”

“…donax is a C3 species with particularly high assimilation and transpiration rates (Rossa et al, 1998;Webster et al, 2016) that are comparable to several C4 species. Presently, A. donax is not considered a halophyte because it primarily invades freshwater habitats (Nakley and Kim, 2015), but its salt tolerance has been proved worldwide: California, South Africa (Bell, 1997;Rossa et al, 1998), and Australia (Williams et al, 2008).…”

Rising CO2 from historical concentrations enhances the physiological performance of Brassica napus seedlings under optimal water supply but not under reduced water availability

“…Intrinsic water-use efficiency was calculated as A max /g s . The ratio (A max /g s ) is considered to be more reliable than the water-use efficiency calculated from CO 2 assimilation to transpiration rate because it is not affected by the VPD inside the leaf chamber (Webster et al 2016). All the data were collected after the leaf achieved a steady state, and minimum fluorescence (F s ) and maximum fluorescence (F m 0 ) were recorded by ensuring a light-saturating pulse of 8000 μmol m À2 s À1 .…”

Impact of high phosphorous and sodium on productivity and stress tolerance of Arundo donax plants

“…Arundo donax L., the giant reed, is a non-food perennial rhizomatous invasive grass species belonging to Poaceae family (Pilu et al , 2012). A. donax is one of the most efficient C3 plant species, able to colonize a wide spectrum of habitats worldwide, from very wet loam to relatively dry sandy soils (Webster et al , 2016). A. donax displays a high photosynthetic rate and a fast-growing habit that make its cultivation suitable for biomass and bioenergy production (Webster et al , 2016; Sánchez et al , 2016).…”

“…A. donax is one of the most efficient C3 plant species, able to colonize a wide spectrum of habitats worldwide, from very wet loam to relatively dry sandy soils (Webster et al , 2016). A. donax displays a high photosynthetic rate and a fast-growing habit that make its cultivation suitable for biomass and bioenergy production (Webster et al , 2016; Sánchez et al , 2016). In addition, the tolerance to abiotic stress of A. donax has been already demonstrated across a range of stressful conditions, thus allowing the exploitation of degraded and marginal lands with A. donax crops (Calheiros et al , 2012; Nackley and Kim, 2015).…”