Abstract: By the method of yield component, a simulation model on barley yield f ormation was established, which could be available for different barley cultivar s in different areas. The establishment process of the model was as the followin g. With the yield components of different cultivars under optimal conditions in Wuhan, Yangzhou, and Kunming as the bases, the regression equations of the relat ive values of ears per plant, kernels per ears, and thousand-grain weight with the accumulated photosynthetic effective radiation (∑PAR) were established, and the functional relations between the ears per plant, kernels per ears, and thou sand-grain weight under actual conditions as well as their potential values und er optimal conditions and the variables soil moisture regime and nutrient conten ts under actual conditions were formed. The model more comprehensively considere d the internal and external factors of barley growth and development. The intern al factors reflecting the genetic properties of cultivar included potential ears per plant, potential kernels per ear, potential thousand grain weight, and grai n-filling duration; while the external factors included ∑PAR and soil moistur e regime and nutrient contents. Field experiments with different barley cultivar s at different sowing dates were conducted in Wuhan, Kunming, and Yangzhou, and the data obtained were used to calibrate and validate the model. The results sho wed that the model better simulated the yield components and theoretical yield, with the average absolute values of relative error (RE) of ears per plant, kerne ls per ear, and thousand-grain weight being 196%, 188% and 167%, respe ctively. The correlation coefficient from y=x regression analysis on the sim ulated and observed values of the three yield components and theoretical yield w as between 09464 and 09987, indicating that this model was more predictab le and applicable.

Key words: shelter forest,  , Landsat TM, SPOT5, Three-North region.