Abstract

Since the most widespread limiting factor in agricultural production is water stress, a two year field experiment was carried out in Karaj, Iran during 2008 to 2010 growing seasons to assess the effect of water stress on yield and yield components of spring rapeseed (Brassica napus L.) cultivars in winter planting to find the most tolerant cultivars. The experiments was laid out in a four-replicated-randomized complete block, split plot design with two irrigation levels (I: I₁= irrigation on the basis of 80 ml evaporation from the class A pan (normal irrigation) and I₂= interruption of irrigation from the flowering stage (water stress) as the main plot) and cultivar including C₁: RGS 003, C₂: Amica, C₃: Sarigol, C₄: Option 500, C₅: Hyola 401, C₆: Hyola 42, C₇: Hyola 60, C₈: Hyola 420, C₉: Hyola 330, C₁₀: Hyola 308, C₁₁: Kimberly, C₁₂: RGS 006, C₁₃: 19-H, C₁₄: Syn-3, C₁₅: PR-401/16, C₁₆: PP-401/15E, C₁₇: PP 308/8, C₁₈: PP 308/3, C₁₉: ORS 3150-3006, C₂₀: ORS 3150-3008, C₂₁: RG 4403, C₂₂: RG 405/03, C₂₃: RGAS 0324 and C₂₄: RG 405/02 as subplot. The results of combined analysis of two years revealed that under normal irrigation condition ORS 3150-3008 and under water stress condition RG 405/03 cultivars produced the highest seed yield by average of 2285 and 1544 kg ha^-1, respectively.

Key words: Rapeseed, Brassica napus L., spring cultivars, water stress, yield and yield components, winter planting.