Ecotypic responses of switchgrass to altered precipitation

Abstract

Anthropogenic climate change is projected to alter precipitation patterns, resulting in novel environments for plants. The responses of dominant plant species (e.g. Panicum virgatum L. (switchgrass)) to climate changes can drive broader ecosystem processes such as primary productivity. Using a rainfall mesocosm facility, three ecotypes of P. virgatum (collected from Kansas, Oklahoma and Texas, USA) were subjected to three precipitation regimes (average, -25%, +25%) to determine the physiological and growth responses to altered precipitation in a common garden setting. Results showed mean maximum photosynthetic rates, stomatal conductance, transpiration, midday water potential and dark-adapted chlorophyll fluorescence were lowest in the Kansas ecotypes. Increased precipitation treatments raised the mean midday water potentials and lowered water-use efficiency. Aboveground biomass responded positively to changes in precipitation, but flowering initiation was later and rates were lower for Texas ecotypes. In general, ecotype origin was a better predictor of differences in physiological responses and flowering, whereas the precipitation treatments had greater control over biomass production. Depending on the growth variable measured, these results show responses for P. virgatum are under varying ecotypic or environmental control with few interactions, suggesting that future predictions to climate change need not inherently consider localised adaptations in this economically important and widely distributed species.

QTL and Drought Effects on Leaf Physiology in Lowland Panicum virgatum

“…Classic physiological studies addressed differences in leaf performance between ecologically differentiated upland and lowland switchgrass populations with distinct vegetative phenotypes and ploidy levels [32,34]. Evidence for local adaptation [35,36] has also led to more recent experiments focused on inter-population variation in productivity and physiological performance [6,33,[37][38][39][40]. Results from these experiments support differences in seasonal patterns of photosynthetic performance that complement adaptive variation in phenology [33,39,40].…”

Genotypic variation in traits linked to climate and aboveground productivity in a widespread C4 grass: evidence for a functional trait syndrome

“…In comparison, Hartman et al (2012) found no differences in A CO2 per unit transpiration among three latitudinally separated P. virgatum populations, yet significantly higher photochemical efficiency in southern populations.…”

Water Use Efficiency by Switchgrass Compared to a Native Grass or a Native Grass Alfalfa Mixture

“…In contrast, switchgrass has been reported to be impacted by changes in water availability. Earlier reports [20,35] indicated that WUE declines with increased water availability in switchgrass. Stout et al [21] indicated soil attributes, such as water holding capacity, make the largest contribution to WUE in switchgrass under variable precipitation scenarios.…”

“…However, other factors besides photosynthetic pathway affect WUE. Switchgrass biomass production is strongly driven by precipitation, but as precipitation increases, WUE decreases [20]. Precipitation variability can impact switchgrass WUE and yields [21].…”