Cultivar selection and proper planting density could be employed for increasing grain yield. A field experiment was designed and conducted using a randomized complete block design with four replications at Research Station of Shiraz University Agricultural College in 2000/01 cropping season. The soil texture was silty clay loam. Effect of three plant densities 30, 50, and 70 plants/ m2 on yield and yield components of two winter rapeseed (Brassica napus L.) cultivars (Talayeh and Okapi) was evaluated. The results indicated that increasing plant density from 30 to 70 plants/m2 was associated with a significant decrease in number of pods/plant in both cultivars. Increase in plant density from 30 to 70 plants/m2 resulted in a significant increase in plant height and reduced branching. Maximum yield per unit area in Talayeh and Okapi was achieved at 50 and 70 plants/m2 density, respectively. Effect of plant density on seed per pod, thousand seed weight, harvest index and seed protein percentage was not significant. In both cultivars the highest mean value of oil and protein percentage was obtained at 30 plants/m2 density, with the higher plant densities reducing both oil and protein percentage.
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