Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 8/29/2012
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Process-level crop models are critical components of agricultural decision support systems. Crop models that respond to biophysical constraints (e.g. weather, soil type, water, and fertilizer supply) and genetic factors can be used to study effects of climate change, land use, and on-farm management practices. Simulating root growth is critical to understand nutrient and water uptake dynamics of the plant, because uptake can only take place in soil layers containing active roots. Potato (Solanum tuberosum L.) is an ideal crop to simulate root processes because growth and yield are sensitive to drought and nutrient deficiencies starting at mild stress levels. The focus of the current work was to incorporate a diffusive root growth model into an existing potato crop model and to validate against observed data. Experimental data were simulated using the potato model SPUDSIM and the soil model 2DSOIL, both developed in the Crop Systems and Global Change Laboratory of USDA-ARS in Beltsville, Maryland. In SPUDSIM, carbon distribution between root, shoot, and tubers is estimated as a function of hourly photosynthetic rate, temperature, physiological age, and the carbon, nitrogen, and water status of the plant. The crop model is coupled to 2DSOIL, which simulates water, heat, and solute (in the form of nitrate) movement, and plant root activity in a two-dimensional soil profile. In 2DSOIL, root growth and movement is estimated taking bulk density, temperature, and water, and nutrient status of the soil into account. Root movement is simulated in two dimensions according to a diffusive scheme. Experimental data from a study conducted in our Soil Plant Atmospheric Research (SPAR) chambers were used to validate the modified model. Data, consisting of leaf, stem, tuber, and root mass at harvest, from six different water and nutrient treatment levels were utilized. Evapotranspiration data were available for all chambers, and soil water data obtained with TDR probes in five different depths were available for three chambers. The diffusive root growth module was calibrated using the experimental root data, taking measured water status of the chambers into account. Experimentally observed carbon allocation shifting towards the root system for stressed plants could be confirmed by modeling results. The model reproduced decreasing shoot and tuber growth of potato under water stress accurately. Modeled and measured soil water profiles and plant transpiration agreed well. The new diffusive root growth model will improve simulation of water and nutrient stress, as well as providing information on root architecture valuable for plant breeders.