Cool temperature effects on photosynthetic parameters of two biomass fuel feedstocks in a low light intensity environment

Abstract

The ability to attain the feedstock production goal in the USA for biofuel production is limited by available arable land, cool temperatures, and periods of low light intensity. This study investigates the effects of warm and cool temperatures growth conditions in a low light regime on the photosynthesis and growth of switchgrass (Panicum virgatum cv. Alamo) and giant miscanthus (Miscanthus giganteus). Alamo switchgrass did not acclimate to low light conditions and had a 47% lower growth and significantly lower mean light saturated photosynthetic rate (A_sat = 10.3 μmol m⁻²s⁻¹) at 14/12°C day/night, compared with 28/25°C (A_sat = 18.8 μmol m⁻²s⁻¹). In contrast, photosynthesis of giant miscanthus acclimated to low light conditions, but there was no significant decrease in quantum requirement or light saturated photosynthetic rates in cool growing conditions (A_sat = 8.2 μmol m⁻²s⁻¹ and 7.0 μmol m⁻²s⁻¹ for warm and cool conditions, respectively). In summary, giant miscanthus growth and photosynthesis is relatively more tolerant of cool temperature than switchgrass, but is severely limited by low radiation. In contrast, Alamo switchgrass growth and photosynthesis is very sensitive to cool conditions, but is able to maintain higher growth than miscanthus at low radiation conditions.

Keywords:

• CO₂ response curve
• fluorescence kinetics
• light acclimation
• stomatal conductance

Acknowledgements

Thanks to Debbie Wiley who assisted with growing, pest maintenance and watering the plants while they resided in the BIOL/VBI plant growth facility.

This work was supported by the Southeastern Sungrant initiative under grant No. DTOS5907G00050.