Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/24/2012
Publication Date: 1/24/2013
Citation: Fleisher, D.H., Barnaby, J.Y., Sicher, Jr., R.C., Resop, J.P., Timlin, D.J., Reddy, V. 2013. Effects of elevated CO2 and cyclic drought on potato under varying radiation regimes. Agricultural and Forest Meteorology. 171-172:270-280. Interpretive Summary: Climate change predictions suggest that drought will become more frequent, affecting agricultural production in many areas of the world. Potato is grown intensively in the United States and is water sensitive. Yields will decrease when rainfall or irrigation drop to levels even slightly lower than usual over the course of an entire growing season. Little is known, however, how potato plants will respond to shorter periods of drought just one to two weeks in length. Since climate change predictions also include higher levels of atmospheric carbon dioxide concentration, multiple experiments were conducted to study potato yield under short periods of water stress and different levels of carbon dioxide. The results show that potato plants under short periods of drought will start to grow more tubers, and less leaves, than those potatoes not under water stress. However, because they grow less leaves, yield will decrease over the course of the season compared to non-stressed plants. Results also showed that yields will increase when carbon dioxide levels rise above the current level in the atmosphere. Such findings will help farmers and crop consultants more efficiently manage their water resources today and in the future as drought becomes more frequent. The data is also useful for scientists to develop mathematical tools to help improve management practices for agricultural systems.
Technical Abstract: Two experiments were conducted to evaluate effects of short-term drought on different growth stages of potato (Solanum tuberosum L. cv Kennebec) under ambient and elevated atmospheric carbon dioxide concentrations (CO2). Drought cycles were applied at post-tuber initiation (R) or at both vegetative and post-tuber initiation (VR) growth stages. The experiments E1 and E2 were run in the same growing season in outdoor sunlit soil-plant-atmosphere research chambers. Identical temperature regimes were used, but planting dates differed in order to allow for variation in solar radiation (daily average photosynthetically active radiation (PAR) of 43.9 mol per square meter per day in E1 and 24.7 in E2). Despite this variation, most results were consistent among the experiments. Total dry matter production was reduced proportionately based on the number of drought cycles, with VR plants generally producing less biomass as compared to non-droughted controls. Harvest index and the ratio of tuber to total dry matter growth rate increased with drought frequency, suggesting that tuber sink strength was higher for VR plants than R. Harvest index, the ratio of tuber to total plant growth rate, and tuber dry matter for VR and R treated plants were also higher at elevated versus ambient CO2. Water use efficiency for water deficient versus water sufficient plants was correlated with harvest index and also increased at the higher CO2 concentration. As there was also little influence of drought or CO2 on leaf extension characteristics, differences in dry matter production and allometric responses were assumed to predominantly be a function of assimilation rate and carbon partitioning. These results confirm potato drought sensitivity in terms of yield response is influenced by developmental stage and atmospheric CO2 concentration.