Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 19, 2006
Publication Date: November 12, 2006
Citation: Fleisher, D.H., Timlin, D.J., Reddy, V. 2006. Potato Gas Exchange and Canopy Development Responses to Drought and Atmospheric Carbon Dioxide. 2006 ASA-CSSA-SSSA Annual Meeting. P. 47.
Potato is very sensitive to drought, with yield reduction occurring under moderate levels of water stress. Projected increases in global atmospheric carbon dioxide concentration (CO2) may help mitigate the impact of drought on potato production. Despite the agronomic importance of this crop, studies on the interaction of water stress and CO2 on seasonal potato growth and development have not been conducted. A soil-plant-atmosphere research (SPAR) chamber experiment was conducted using 12 chambers with six chambers maintained at either ambient (370 ppm) or elevated (740) CO2. Varying amounts of irrigation were supplied to each chamber on a daily basis according to 90, 75, 50, 25, and 10% of the daily water uptake measured for the control chamber of each CO2 treatment (100%). Elevated CO2 increased end of season biomass at each irrigation level as compared to ambient CO2. The maximum increase was 44% at the 10% irrigation treatment. Yield response was nonlinear and peaked at moderate levels of water stress (between the 50 and 75% irrigation treatment). Plant yield at elevated CO2 was consistently higher than ambient CO2 at each irrigation treatment. Harvest indices increased with drought, reaching a maximum value of 0.6 with elevated CO2. Water use efficiency (WUE) increased with drought and ranged from 5 to 15 and 11 to 30 kg yield m-3 for ambient and elevated CO2 respectively (tuber fresh weight basis). Leaf appearance and expansion rates, and stem elongation rates were linearly correlated with irrigation. The length of time for which leaves continued to appear in the canopy was reduced by 8 days at elevated CO2. Lateral branch formation was suppressed under elevated CO2 for most of the treatments allowing the additional assimilate to be partitioned to below ground organs. Seasonal net assimilation data showed enhanced growth at increased CO2 primarily during the middle and end of the growing season as compared with ambient CO2. These results indicate that potato productivity is improved under enriched CO2 under drought conditions.