Interannual Variations of Switchgrass Physiology, Growth, and Soil Respiration under Precipitation Changes

Adrian Harris, Tennessee State University


Plant ecophysiology, biomass, and yield are often influenced by climatic factors such as precipitation. But the interannual variations of switchgrass photosynthesis, biomass, and soil respiration have not been well investigated, particularly under different precipitation changes. We have conducted two long-term precipitation experiments with switchgrass under precipitation changes, one in a greenhouse and another one in a field, since 2014. The experiments used a randomized block design with 5 precipitation treatment levels (–50%, –33%, ambient, +33%, and +50% of ambient precipitation). Five blocks were used for the greenhouse experiment and four blocks were used for the field study. We measured switchgrass leaf physiology (photosynthesis, stomatal conductance, transpiration and water use efficiency), biomass, and soil respiration over the years. The results showed that there were large interannual variations of these variables among years. Precipitation treatment significantly influenced leaf photosynthesis, biomass, and soil respiration, but the variations in the field were not similar to those in the greenhouse as expected. Strong interannual variations were found for photosynthesis, biomass, and soil respiration. Our results indicated that while switchgrass is a drought tolerant grass, extreme precipitation changes can significantly influence switchgrass growth and soil respiration. When comparing the greenhouse data to the field data, the trends were similar for the treatments, but there were no consistent trends with for photosynthesis and soil respiration among years.

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Recommended Citation

Adrian Harris, "Interannual Variations of Switchgrass Physiology, Growth, and Soil Respiration under Precipitation Changes" (2020). ETD Collection for Tennessee State University. Paper AAI28154415.