|RESOP, JONATHAN - University Of Maryland|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2014
Publication Date: 10/29/2014
Citation: Fleisher, D.H., Barnaby, J.Y., Sicher Jr, R.C., Resop, J., Timlin, D.J., Reddy, V. 2014. Potato gas exchange response to drought cycles under varying radiation environment and CO2. Agronomy Journal. 106:2024-2034. DOI: 10.2134/AGRONJ.14.0220.
Interpretive Summary: Potato is the fourth most commonly grown crop in the world based on area. Potato is also known to be drought sensitive. This is problematic for two reasons. One, because many regions in the world, including parts of the United States, are rain-fed and farmers do not always have access to irrigation water, and, two, because climate change predictions suggest rainfall patterns will decrease over many of these productive regions. Strategies for farmers to adapt their water management practices need to be developed in anticipation of these changes in weather. However, little is known how potato growth and yields will be impacted by these increased periods of drought and how higher carbon dioxide concentrations influence water management. Two experiments were conducted on potato plants exposed to short-term periods of drought and different carbon dioxide levels. The data showed that growth rates and yield decreased for plants exposed to just an 11 day period of drought. Higher carbon dioxide levels helped reduce some of this impact on yield and also reduced water requirements for the plants. Such findings will help farmers and consultants adapt their water management practices in the future conditions of increasing carbon dioxide and decreasing water availability. The data are also useful for scientists to study desirable breeding characteristics for new potato varieties and improve ways in which agricultural systems can be adapted to climate change.
Technical Abstract: Episodic drought is likely to increase in potato (Solanum tuberosum L.) production regions according to climate change predictions. Future carbon dioxide concentrations (CO2) will influence the impact of water stress, but little is known regarding short-term drought and CO2 effects on photosynthesis and transpiration. Two experiments, differing in the quantity of solar radiation, were conducted in soil-plant-atmosphere-research (SPAR) chambers. Plants were grown at ambient (aCO2) and twice-ambient CO2 (eCO2) and received one of three irrigation treatments: no water stress (C), or short-term (11 to 16 day) water-withholding during both vegetative and post-tuber initiation stages (VR), or post-tuber initiation (R) only. Seasonal net photosynthetic rate (AN) declined according to C, R, and VR treatments for both CO2 levels. AN was greater for eCO2 versus aCO2 C and R treatments, but similar for VR. Water use efficiency (WUE) increased for eCO2 at all irrigation levels. Canopy conductance to CO2 transfer (Tau) and water vapor (Gv), light use efficiency (alpha), daily AN, and evapotranspiration (E) immediately decreased at the onset of each drought cycle. There was no consistency with respect to the rate of decrease among R or VR treatments at either CO2 level. Gv declined more sharply than AN, resulting in higher WUE during the drought, particularly for eCO2. Relative responses to drought and CO2 were similar among both experiments, but the significance of responses among treatments was greater under higher solar radiation. These findings were similar to those reported under longer-term potato water-withholding studies, suggesting that interactions between CO2 and drought on potato carbon assimilation and water use are likely to be conserved across production zones with varying radiation and rainfall patterns. Such trends will be useful for developing adaptive management responses for irrigation practice under future climates.