Soybean Reproductive Development: Adapting a Model for European Cultivars

Abstract
The objective of this study was to simulate reproductive development and yield potential of new soybean [Glycine max (L.) Merr.] lines that might be grown in different European locations. The SOYGRO model was adapted to European crop conditions with respect to genetic parameters for pod set, pod growth, seed set, and seed enlargement. The structure of reproductive development in the model takes into account the hierarchy in assimilate partitioning for pod addition, shell growth, and seed initiation. This aspect was described in relationship with canopy photosynthesis, temperature, and photoperiod. A sensitivity analysis was conducted on yield variations with 11 parameters representing phenological traits, characteristics of pod and seed development, and foliage growth in order to identify the main genetic parameters. Field determinations of pod numbers computed from R5 to R7 on current cultivars and new lines belonging to indeterminate and determinate types showed two kinds of fruiting processes, which appear to be independent of growth habit and maturity group. Based on the comparison of the dynamics of observed pod addition for the reference cultivars, a simple procedure was proposed to calibrate the genetic parameters for new cultivars. This new procedure allowed validation of pod production and yield and provided good agreement with field data collected in several locations in Europe.