Ezzatollah Askari Asli - Ardeh - Department of Engineering Biosystem, Faculty of Agriculture & Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
Gholamreza Taghizadeh - Department of Engineering Biosystem, Faculty of Agriculture & Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
Ebrahim Taginezhad - Department of Agricultural technology engineering, Faculty of Agriculture & Natural Resources Moghan, University of Mohaghegh Ardabili, Ardabil, Iran

In many research institutes, it is necessary to thresh the product in clusters. For this purpose, a laboratory threshing unit is used. The purpose of this study was to investigate the effect of some factors including to common barley varieties in Ardabil province (Aras and Sahra), cluster amount (۱۰ and ۱۵ g), blade speed (۴۵۰, ۶۰۰ and ۷۵۰ rpm), threshing time (۱۰, ۲۰ and ۳۰ s) and the blade clearance from the bottom of the cylinder (۲.۵ and ۳.۵ mm). An inverter was used to change the speed of the thresh blade. A four-factor randomized complete block design (RCBD) was used to analyze the data. The results of analysis of variance showed that the effects of independent factors as well as the interactions of independent factors including cluster amount, blade clearance, blade speed and threshing time on threshing losses and damaged grains percent (except for the main interactions of blade speed in experiment with Sahra variety) was significant. The lowest and highest mean of damaged grain percent belonged to Aras and Sahra varieties, respectively. In general, threshing losses of Aras variety were higher than Sahra variety, but the damaged grains percent of Aras variety was lower. According to the results of the interactions of four factors,  two factors the device evaluation, the best working conditions (minimum threshing loss and lowest damaged grains percent) in exchange for tests with cluster amount of ۱۵ g, blade clearance of ۳.۵ mm, blade speed ۶۰۰ rpm and the threshing time was ۳۰ s.

threshing losses, Laboratory threshing, damaged grains percent, Barley