|HUI, DAFENG - Tennessee State University|
|YU, CHIH-LI - Tennessee State University|
|DENG, QI - Tennessee State University|
|DZANTOR, E - Tennessee State University|
|ZHOU, SUPING - Tennessee State University|
|DENNIS, SAM - Tennessee State University|
|SAUVE, ROGER - Tennessee State University|
|JOHNSON, TERRANCE - Tennessee State University|
|SHEN, WEIJN - Guangzhou University|
|LUO, YIQI - University Of Oklahoma|
Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2018
Publication Date: 2/8/2018
Citation: Hui, D., Yu, C., Deng, Q., Dzantor, E.K., Zhou, S., Dennis, S., Sauve, R., Johnson, T.L., Fay, P.A., Shen, W., Luo, Y. 2018. Effects of precipitation changes on switchgrass photosynthesis, growth, and biomass: A mesocosm experiment. PLoS One. 13(2):e0192555. https://doi.org/10.1371/journal.pone.0192555.
Interpretive Summary: The warm-season grasses common in Southern Plains grasslands usually face a shortage of water that reduces their growth and biomass production. For crops such as switchgrass, which is grown to produce biomass feedstock for bioenergy production, water shortages reduce biomass yield. Warm-season grass like switchgrass are adapted to survive periods of water shortage, but understanding the threshold degree of water shortage beyond which growth becomes limited is needed to devise improved stand management strategies and to predict yield given variable precipitation. We conducted a two-year precipitation simulation experiment using large pots (95 L) in an environmentally controlled greenhouse in Nashville, TN. Five precipitation treatments (ambient precipitation, and -50%, -33%, +33%, and +50% of ambient) were applied to "Alamo" switchgrass plants one year after they were established from tillers. Increased precipitation resulted in increased aboveground biomass, except there was no difference in biomass between +33% and +50% precipitation. Biomass increased with precipitation because plants grew taller and because plants produced more growing stems. This demonstrates switchgrass growth may be reduced by water shortage even in average years. This information can assist growers and breeders by illuminating water level of water shortage may impact yield and provide a target for improving drought tolerance.
Technical Abstract: Climate changes, including chronic changes in precipitation amounts, will influence plant physiology and growth. However, such precipitation effects on switchgrass, a major bioenergy crop, have not been well investigated. We conducted a two-year precipitation simulation experiment using large pots (95 L) in an environmentally controlled greenhouse in Nashville, TN. Five precipitation treatments (ambient precipitation, and -50%, -33%, +33%, and +50% of ambient) were applied in a randomized complete block design with "Alamo" switchgrass plants one year after they were established from tillers. The growing season progression of leaf physiology, tiller number, and height and aboveground biomass were determined each growing season. Precipitation treatments significantly affected leaf physiology, growth, and aboveground biomass. The photosynthetic rate in the +50% treatment was 18.7 µmol CO2 m-2s-1, significantly higher than other treatments. The biomass in the +50 % treatment was twice that in the -50% treatment. Compared to the ambient treatment, the -33% treatment did not influence leaf physiology, plant growth, and aboveground biomass, but the -50% treatment significantly reduced plant height and aboveground biomass. This study demonstrated that while switchgrass is a drought tolerant grass, severe drought significantly reduces its growth and biomass, and that high precipitation stimulates photosynthesis and growth.