مسعود بازگیر - Assistant Professor, Department of water Resources, Ilam University, Ilam, Iran
سعید بازگیر - Assistant Professor, Department of Physical Geography, University of Tehran, Tehran
جواد میرزایی - Assistant Professor, Department of water Resources, Ilam University, Ilam, Iran

Talandasht plain, a semi-arid area in Kermanshah province is well known for itswheat and barley rainfed agriculture. The main objective of this study was, toassess the actual yield of wheat and barley and to determine the reasons of the lowproduction. The potential yield of both crops has been simulated at three differenthierarchical levels, using a semi quantitative crop growth model. The RPP ofwheat and barley was 7.67 t/ha and 4.78 t/ha, respectively. Values for WPP rangebetween 3.43 and 3.94 t/ha for wheat and between 2.70 and 3.06 t/ha for barley.The LPP range from 2.84 to 3.60 t/ha for wheat, and from 2.21 to 2.79 t/ha forbarley. Wide gaps between the simulated yields and the observed yields for wheatand barley were obtained. The most important yield limiting factor was watershortage. Therefore, further research is recommended for water conservationtechnique and improvement of agricultural management level in the study area.

Crop growth modelling, Yield gap analysis, wheat, Barely, Rainfed, Kermanshah