In order to evaluation of influence of sulphur fertilizer on grain yield and the some of physiological indices of canola, an split plot experiment based on randomized complete block design was conducted in Research Farm Islamic Azad University, Ardabil branch in 2007. Factors were: sulfur fertilizer at four levels (0 as control, 25, 50 and 75 kg S/ha) in the main plots and canola cultivars at three levels (Fornax, Opera and Slmo) in the sub plots. The results showed that various levels of sulfur fertilizer affected yield and yield components of canola. Means comparisons in compound of treatment cultivar× levels of sulfur showed that maximum grain yield was obtained by the plots which was applied 75 kg sulfur/ ha with opera cultivar. Similar results were obtained in grain per pod, pod per plant and thousand kernel weights. Investigation of variances of dry matter accumulation indicated that in all of treatment compounds, it increased slowly until 212 days after sowing with increasing of sulphur fertilizer and then increased rapidly till 296 days after sowing. From 296 days after sowing till harvest time, it decreased due to increasing aging of leaves and decreasing of leaf area index. Increase in S levels also significantly increased the crop growth rate and the maximum of it was observed by the plots that received 75 kg S/ha with opera cultivar. In addition, in all of treatment compounds, CGR increased slowly until 240 days after sowing and then decreased slowly till 254 days after sowing. From 254 days after sowing till harvest time, it decreased due to increasing aging of leaves and decreasing of leaf area index. Thus, it can be suggested that in order to increasing of grain yield, dry matter accumulation, crop growth rate and the other of physiological indices should be applied opera cultivar with 75 kg S ha-1 in conditions of Ardabil Plain.
