Compensatory photosynthesis in Pseudoroegneria spicata

Understanding plant ecophysiological functioning is critical in
formulating effective ecologically-based strategies to conserve and
enhance resiliency and resistance in sagebrush steppe, as well as
improving their restoration following degradation by interactive effects
of climate change, wildland fire, and invasive annual grasses. 
Recent research has shown increased reproductive photosynthesis following
floral defoliation can be important to reproductive potential, yet how
this is expressed in plant material selected for different functional
attributes is unknown.  To address this, we measured
photosynthetic gas exchange in clipped and unclipped basal florets and
flag leaves of two germplasms of the native perennial bunchgrass,
bluebunch wheatgrass, var. Anatone and var. Columbia, selected for higher
reproductive culm production.  Clipping induced a stronger direct
compensatory reproductive photosynthetic response in basal florets of
Anatone compared to Columbia germplasm individuals, with no indirect
compensatory response apparent in unaffected distal florets of either
germplasm.  Flag-leaf photosynthesis did not differ between the
germplasm lines, but Columbia flag leaves did show evidence of increased
photosynthesis on culms with clipped basal florets.  These
findings suggest selection for increased flowering culms may alter
reproductive herbivory tolerance, a feature important in the convergence
of herbivory and drought tolerance traits.  Such information
could help in planning effective seed mixes to enhance population
stability across highly variable sagebrush steppe ecosystems, as well as
directing future plant material selection to improve restoration success
in these economically important rangelands.