Comparing observed with simulated data in 1994, the modi®ed model decreased the root mean square error
(RMSE) for biomass at harvest and seed yield from 1714 to 466 and from 940 to 333, respectively. For 1995, the validation
year, RMSE for biomass decreased from 1366 to 352, although the yield was now overestimated with no signi®cant change in
RMSE. The average simulated harvest index (HI) for 1995 was greater than for 1994, the reverse of the measured values