(international Journal of Biosciences (IJB
In order to investigation of CROPGRO-Soybean model under four sowing date management in some of growth unlimited cultivars of soybean in Karaj, this experiment carry out as a randomized complete block design in split plot arrangement with four replications in 2010. Treatments were different planting date 19 May, 29 May, 9 Jun, 19 Jun as main plot and four growth limited cultivars of soybean (Wiliams and Zan) as sub plot. Result showed that variety dimension of RMSE for biomass had 356.41-1207.33. Also variety dimension of Wilmot coefficient (d) calculated between 0.898-0.989. The Wiliams cv in planting date 19 May with RMSE= 356.41 kg/ha and d=0.989 have been highest of model coefficient efficiency. In all of treatments variety dimension of R2 curve 1:1 measured and predicted rates, equal to 0.855-0.988 and correlation coefficient at (p< 1%) was significant .The variety dimension of RMSE for grain yield all of the treatments had 151.94-880.66 kg/ha. Also variety dimension of d coefficient calculated between 0.505-880.66 kg/ha.