Abstract
Individual variability generally exists in crop fields. It increases with an increase in plant population density, water or nutrient deficiency, or spatio-temporal irregularity , and often results in a reduction in yield. As individual variability exists in a community but is expressed through individuals, we studied it by applying two models, one at the stand level and the other at the individual level. The crop model PILOTE and the functional structural plant model (FSPM) GreenLab were applied to a field of maize (Zea mais L.) to provide a numerical description of the crop at different levels. The delay and slower increase in LAI and in total dry matter at stand level compared to individal level, led us to hypothesize that uneven emergence could have an effect on variablity. We derived a theoretical distribution of germination dates, which supported this hypothesis. In parallel, we used GreenLab to analyse possible sources of variablity in acumulated biomass within a dynamic system, and to estimate possible parameters from experimental data. Using PILOTE and GreenLab, we successfully identify two typical types of individual variability in the maize field: variability in development over time and variability in competition for space during growth. Our method could be used in future research on the cause and influence of individual variabilty on performance, and to identify the link between an FSPM based on individual plants and a crop model at stand level.