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United States Department of Agriculture

Agricultural Research Service

Research Project: MECHANISTIC PROCESS-LEVEL CROP SIMULATION MODELS FOR ASSESSMENT OF AGRICULTURAL SYSTEMS

Location: Crop Systems & Global Change

2012 Annual Report


1a.Objectives (from AD-416):
The overall objective is to refine and improve existing simulation models for corn and potato by developing new, and improving existing functional relationships between physiological processes and nutrients in the soil and plant tissues. Results of this research will be used to address existing knowledge gaps in the models. The modified models will be evaluated by testing simulated responses at plant component and whole plant levels. The specific sub-objectives are to improve simulation of the above- and below-ground potato and corn processes in the areas of: (1) water and nutrient stress effects on growth, development, morphology, and yield, and (2) response of root growth and activity (water and nutrient uptake) to soil nutrients (N, P and K), and water. The model and new components will be evaluated using experimental data. The potato and corn models, along with a rye cover crop model and existing models for soybean and corn, will then be used for assessment of the environmental consequences of agricultural management practices on carbon sequestration and nutrient balances. These practices include fertilizer applications, rotations, and cover crops.


1b.Approach (from AD-416):
Mechanistic models for soybean (GLYCIM), cotton (GOSSYM), corn (MAIZSIM) and potato (SPUDSIM) have been developed in previous projects by this group. The proposed research will broaden the capabilities of the corn and potato models by utilizing data from experiments carried out in unique, state-of-the-art sun-lit growth chambers and field plots. Short and long term experiments will be employed to test hypotheses and develop algorithms for plant processes to be used in the computer models. Data collected by collaborators will be used to test and evaluate the models. A simple Rye model will be developed to simulate a cover crop during the fall-winter season. A computer graphical user interface will be developed using components from the existing software program, GUICS, to allow a user to simulate long term crop rotations over multiple growing seasons. Advanced data management capabilities will be added to the interface to help with interpretation and management of input and output data. Tools for weather generation and estimation of soil hydraulic properties will be added to the interface to provide a wide range of environmental conditions for assessment. All crop models will be used within the new interface to assess the environmental and economic impacts of climate change on carbon sequestration, and nitrogen and water balances for relevant production systems.


3.Progress Report:
Experiments were conducted in outdoor Soil Plant Atmosphere Research (SPAR) growth chambers to (1) evaluate effects of periodic drought on potato growth and gene expression at two different stages of development, and at ambient and elevated atmospheric CO2 concentration, and (2) quantify the long-term growth response of potato to three different levels of atmospheric CO2 concentration where a heat stress cycle was imposed to evaluate metabolic responses to elucidate possible adaptation responses to climate change. Another SPAR experiment was carried out to evaluate the energy balance inside SPAR chambers in an effort to validate plant responses to carbon dioxide measured inside growth chambers versus those reported in open-face field CO2 enrichment studies. Collaborations with potato growers in Maryland's Eastern Shore and Presque Isle, Maine were undertaken to collect periodic samples of potato production under different site-specific growing conditions for calibration of the SPUDSIM potato model. Work was completed evaluating methods to improve experimental protocols when utilizing sophisticated plant measurement systems for estimating climate change responses on potato. A SPAR study was carried out to quantify relationships among stomatal conductance, abscisic acid (ABA), water uptake and photosynthesis using different levels of water stress and CO2. Simulations to assess climate change impacts on corn production were carried out for four U.S. and international sites (U.S. [Iowa], France, Brazil, and Tanzania) using MaizSim. Model results are being compared to those from other models as part of the Agricultural Model Improvement Program (AgMip) collaboration. Continued collaboration with scientists in Ft. Collins, Colorado for the corn model evaluation and implementation. Also continued collaboration with the Vegetable Crops Research Unit in Prosser, Washington and the University of Maryland to validate and test the potato model. Water stress and uptake routines were fully integrated into the potato model SPUDSIM and tested using SPAR chamber data and datasets from Prosser, Washington. The potato model SPUDSIM was coupled with geospatial databases to simulate potential production capacity in Maine. The progress is fully described in the report for project 1265-61660-006-11R. Continued work with the Natural Resources Conservation Service (NRCS) to evaluate the APEX model for use in the Conservation Effects Assessment Project program (CEAP). The progress is fully described in the reports for projects 1265-61660-006-01R and 1265-61660-006-09S. Improved temperature response functions for leaf growth were incorporated into MaizSim and tested using field and SPAR data. The progress is fully described in the report for project 1265-61660-006-10S. Controlled environment experiments were carried out to study cotton and soybean growth, photosynthesis, and soybean seed yield response to phosphorus nutrition under current and projected atmospheric CO2 concentration. A new diffusive root model was incorporated into MaizSim and SpudSim. The progress is fully described in the report for project 1265-61660-006-03S.


4.Accomplishments
1. The response of leaf growth and development to elevated temperatures simulated by the corn model MaizSim was improved. Improved leaf addition and leaf growth functions that respond realistically to high temperatures near and above the maximum temperature for corn were developed using data both from the literature and from outdoor sunlit controlled environment chambers. The model simulated leaf growth and biomass accurately over a wide range of conditions without field calibration. This work is useful to scientists, growers, and those who develop policy who need to assess the impacts of elevated temperatures on corn development and yield.

2. Elevated CO2 concentrations did not result in additional requirements for phosphorus for potato growth. In these experiments, photosynthetic rate and dry matter production were enhanced by elevated atmospheric CO2 concentration as compared to ambient levels at three levels of phosphorus fertilization. Phosphorus fertilization above the currently recommended rate did not result in yield increases at elevated CO2. Additionally, the findings indicate that this fertilization effect does not change even when soil phosphorus levels are below recommended levels for plant nutrition. This information is useful to scientists, growers and those who develop policy who need to assess the impacts of elevated atmospheric carbon dioxide on nutrient requirements of crops.

3. An automated methodology for conducting crop management analyses along the U.S. Eastern Seaboard was developed for the potato model SPUDSIM. Spatially referenced weather and soil databases from the National Oceanic and Atmospheric Administration (NOAA) and Natural Resources Conservation Service (NRCS) were used as input. This allows the simulation of potato yields over large areas to assess climate effects on potato production in this area. This research is useful to scientists, growers and those who develop policy related to food security and large scale yield estimates.

4. Mathematical models and an accompanying experimental procedure were developed to minimize measurement errors that are common to a widely used leaf photosynthesis measurement device. The new protocols improve accuracy of data used for developing mathematical models of photosynthesis. This research is useful to scientists and others who measure and quantify photosynthesis in plants.


Review Publications
Reddy, V., Fleisher, D.H., Timlin, D.J., Anbumozhi, V., Reddy, K.R., Yang, Y. 2012. Monitoring the vulnerability and need for adaptation planning for food security. In: Anbumozhi, V., Breiling, M., Pathmarajah, S., Reddy, V.R. editors. Climate Change in Asia and the Pacific: How can countries adapt? 1st edition. New Delhi, India: SAGE Publications India Pvt Ltd. p. 36-46.

Yang, Y., Timlin, D.J., Fleisher, D.H., Lokhande, S., Chun, J.A., Soo-Hyung, K., Staver, K., Reddy, V. 2012. Nitrogen concentration and dry matter accumulation in maize crop: Assessing maize nitrogen status with an allometric function and a chlorophyll meter. Communication in Plant and Soil Analysis. 43(11):1563-1575.

Wang, Q., Fleisher, D.H., Reddy, V., Timlin, D.J., Chun, J.A. 2012. Quantifying the measurement errors in a LI-6400 gas exchange system and their effects on the parameterization of Farquhar et al. model for C3 leaves. Photosynthetica. 50(2):223-238.

Anbumozhi, V., Breiling, M., Pathmarajah, S., Reddy, V. 2012. Climate change in Asia and the Pacific: How can countries adapt? New Delhi, India: Sage Publications. 400 p.

Fleisher, D.H., Wang, Q., Timlin, D.J., Chun, J.A., Reddy, V. 2012. Response of potato gas exchange and productivity to phosphorus deficiency and CO2 enrichment. Crop Science. 52:1803-1815.

Last Modified: 8/1/2014
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