Comparison of Periodic Drought At Two Different CO2 Levels.

Future climate change predictions include the possibility of decreased rainfall and periods of
drought during the growing season for many potato producing regions in the United States.
Such occurrences may be of particular concern for rain-fed areas or where management practices
are already affected by limited water resources. While it is generally presumed that water use
efficiency will increase in response to higher CO2 levels, no experimental data is available to
evaluate the vulnerability of potato (Solanum tuberosum L.) to episodic drought periods when
grown under CO2 enrichment. A study consisting of two experiments was conducted in 6 naturally
sunlit Daylit growth chambers located at USDA-ARS facilities in Beltsville, MD, USA using the
Kennebec variety. Treatments included ambient (400) and elevated (800 ppm) CO2 concentrations
and short-term (ten to twenty day) drought cycles applied at no (control, C), post tuberinitiation
(R), or both vegetative and reproductive (VR) developmental stages. Measurements
including leaf and whole plant gas exchange, plant development, and time-series dry weight data
were used to evaluate the sensitivity of the plants to the drought timing under either growth
CO2. Such information is needed to determine appropriate adaptation strategies to climate
change and can yield valuable insight for future irrigation practice.