Simulating Inbred‐Maize Yields with CERES‐IM

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 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.