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Predicting crop growth and yield with precision are one of the main concerns of the agricultural science. For these purpose mechanistic models of crop growth have been developed and tested worldwide. The feasibility of an expolinear (1997/1998, 1998/1999 and 2002/2003 (1997/1998, 1998/1999 e 2002/2003

Models may be useful tools to design effi cient crop management practices provided they are able to accurately simulate the eff ect of weather variables on crop performance. Th e objective of this work was to accurately simulate the eff ects of temperature and day length on the rate of vegetative node expression, time to fl owering, time to fi rst pod, and time to physiological maturity of faba bean (Vicia faba L.) using the CROPGRO-Fababean model. Field experiments with multiple sowing dates were conducted in northwest Spain during 3 yr (17 sowing dates: 12 used for calibration and fi ve for validation). Observed daily minimum and maximum air temperatures were within the range of -9.0 and 39.2ºC and observed photoperiods within 10.1 to 16.6 h. Optimization of thermal models to predict leaf appearance raised the base temperature (Tb) from the commonly used value of 0.0 to 3.9ºC. In addition, photothermal models detected a small accelerating eff ect of day length on the rate of leaf appearance. Accurate prediction of the fl owering date required incorporating day length, but the solved Tb approached negative values, close to -4ºC. All the reproductive phases aft er fl owering were aff ected only by temperature, but postanthesis Tb was also >0ºC and approached values close to 8ºC for time to fi rst pod set and 5.5ºC for time from fi rst pod to physiological maturity. Our data indicated that cardinal base temperatures are not the same across all phenological phases. A. Confalone,Abbreviations: CLDL, critical long day length; EM, emergence; FL, fi rst fl ower; PM, physiological maturity; PPSEN, slope of relative response of development vs. photoperiod; PTD, photothermal day; SH, fi rst pod; SSE, sum of squared errors; Tb, base temperature; TD, thermal day; Topt1 and Topt2, temperatures between which development proceeds at the maximum rate; Tx, temperature at which the phenological development fails due to excessively high temperature; TRIFOL, rate of appearance of leaves on the main stem.

N-fixing legume crops may be a good component of a general plan to improve cropping system efficiency. For this purpose, crop suitability to specific environments must be established. Vicia faba and Pisum sativum, 1991). In the family of models produced it will select those that best express the crop phenologic response in different phenologic stages.