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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Adaptive Cropping Systems Laboratory » Research » Publications at this Location » Publication #305299
Title: Improving potato drought simulations: Assessing water stress factors using a coupled model

Author
item Fleisher, David
item DATHE, ANNETTE - Norwegian University Of Life Sciences
item Timlin, Dennis
item Reddy, Vangimalla

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/21/2014
Publication Date: 1/3/2015
Citation: Fleisher, D.H., Dathe, A., Timlin, D.J., Reddy, V. 2015. Improving potato drought simulations: Assessing water stress factors using a coupled model. Agricultural and Forest Meteorology. 200:144-155 DOI: 10.1016/J.AGRFORMET/2014.09.018.

Interpretive Summary: Crop models are valuable tools that use mathematics to predict how farm management options, like irrigation, can influence growth and yield. This is important for crops like potato that are very sensitive to water supply. Because most potato models use simple approaches to simulate, or replicate, water stress responses, more realistic equations are needed. A study was done to improve the mathematical parts in a potato model that describe water stress responses. The research found that the new water stress equations could accurately mimic the effects of different quantities of irrigation water on potato. The results showed that it was important for models to capture how water stress reduces potato growth rate within the growing season as well as how the stress causes changes in the way the potato plant increases the mass of the tubers. Farmers, crop consultants, and scientists studying climate change impacts can use the improved models to more confidently evaluate water management strategies for potato.

Technical Abstract: Effective water management is important for drought sensitive crops like potato (Solanum tuberosum L.). Crop simulation models are well suited for evaluating water limited responses in order to provide management and phenotypic-trait recommendations for more efficient production practice. There is considerable variation in how water stress components are implemented with regards to simulating soil, plant, and atmospheric relationships, thereby influencing the utility of model recommendations. Four water-stress factors were developed and implemented in the potato model SPUDSIM in order to assess the contribution each factor provided for improving modeling accuracy. Iterative comparisons versus experimental data consisting of six irrigation treatments were used. Factors included F1, shifts in carbon allocation among shoot and root organs based on soil moisture availability, F2, coupled response of leaf water potential on leaf expansion, F3, and on stomatal conductance, and F4, increased tuber sink strength. F2 and F3 accounted for up to 88 percent of the improvement in root mean square error for total biomass. However, F1 and F4 were necessary to accurately simulate yield. F4 was also required to reproduce trends of increasing water-use efficiency and harvest index with declines in water availability. When the full 4-factor model was considered, simulated responses for total, leaf, stem, and tuber dry weights were within 11 percent of observed values. Daily comparisons for canopy net photosynthesis and evapotranspiration indicated F3 was required to accurately simulate water use, but was too sensitive to very low leaf water potentials. The calibration coefficients used in the model remained stable over all six irrigation treatments, suggesting the full model can be utilized to evaluate water management strategies for potato.