Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/1999
Publication Date: 11/1/2000
Citation: Rasse, D.P., Ritchie, J.T., Wilhelm, W.W., Wei, J., Martin, E.C. 2000. Simulating inbred-maize yield with ceres-im. Agronomy Journal 92:672-678. Interpretive Summary: Technical Abstract Simulation models can be used to help growers evaluate the impact of cultural practices, and the time of application of these practices, on crop productivity. Prior to this work, no simulation model was designed to accommodate the unique cultural practices associated with production of hybrid seed corn. An existing (and widely tested) model of corn growth, CERES-Maize, was changed to simulate growth and development of inbred corn and to accept the unique operations associated with seed corn production (planting the field to a male and female parent in specific rows, detasseling, and removal of male rows after pollen shed). Computer code and equations necessary to describe the changes in corn production from regular grain to seed corn where based on information and number collected in central Nebraska. The reliability of the modified model (CERES-IM) was tested against field observations on crop growth and yield from sites in Michigan. Over all the 35 test sites, the average simulated yield was 75 bu/ac, compared to an average measured yield of 73 bu/ac. Output from the CERES-IM model suggests that the specific time at which the male row is removed from the field greatly influences yield of hybrid seed.
Technical Abstract: CERES-Maize, which was designed for simulation of hybrid maize (Zea mays L.), cannot be applied directly to seed-producing inbred maize because of specific field operations and physiological traits of inbred maize plants. We developed CERES-IM, a modified version of CERES-Maize 3.0 that accommodates these inbred-specific operations and traits, using a set of phenological measurements conducted in Nebraska (NE), and further tested this model with a set of field data from Michigan (MI). Detasseling (i.e., removal of the tassels from the female plants) was conducted prior to silking. Male rows were removed approximately 10 d following 75% silking. The thermal time from emergence to the end of the juvenile phase (P1) and the potential number of kernels per plant (G2) were assessed from field data, and were the only two coefficients allowed to vary according to the inbred line. Rate of leaf appearance of the inbreds was accurately simulated using a measured phyllochron interval of 54 degree-days (°Cd). Simulation of detasseling and male-row removal improved grain yield simulation for inbreds. For a set of 35 inbred-site-year simulations, the model simulated grain yield with satisfactory accuracy (RMSE = 429 kg/ha). Average grain yields were 4556 and 4721 kg ha-1 for the measured and simulated values, respectively. CERES-IM simulations suggest that the effect of male-row removal on grain yield is extremely sensitive to the precise date at which this operation is conducted. This would explain the inconsistent effect of male-row removal on female grain yields reported in the literature.