The objective of the study was to evaluate the effects of row spacing and seeding rates on agronomical traits of three spring canola (Brassica napus L.) cultivars in Iran during 2003-2004. Traits evaluated were plant height, number of seeds pod-1, number of pods main stem-1, number of pods plant-1, 1000-seed weight, seed yield, and seed oil content. The experimental lay-out was split-split plot based on randomized complete block design with 4 replications. 3 row spacing of 12, 18 and 24 cm constituted the main plot, 2 seeding rates of 4 and 6 kg ha-1 as split plot and 3 spring canola cultivars of Hyola 401, Hyola 60 and RGS-003 (lately-used hybrid, new hybrid and new cultivar, respectively) comprised the split-split plot. Results showed that the highest seed yield was obtained at 12 cm row spacing, followed by 7.4% reduction in seed yield as row spacing increased to 24 cm. An increase in seeding rates from 4 to 6 kg ha-1 resulted in a decrease in number of pods plant-1 but other traits were not influenced. The highest number of pods plant-1
was obtained by applying 4 kg ha-1 seeding rates. The hybrid Hyola 401 had better performance than two other cultivars in plant height, number of grains pod-1, number of pods main stem-1, seed yield and seed oil content. The interaction of row spacing × seed rates and also row spacing × cultivars were significant only for the number of pods main stem-1. The lowest one was obtained at 12 cm row spacing with 6 kg ha -1 seed rates. RGS-003 at 12 cm row spacing showed the highest number of pods main stem-1, statistically equal to Hyola 401 grown at 24 cm row spacing.
