. 2010. Impact of production practices on fiber yield of oilseed flax under Canadian prairie conditions. Can. J. Plant Sci. 90: 61Á70. Flax (Linum usitatissimum L.) cultivars commonly grown in western Canada have been developed primarily for seed production. These cultivars tend to be shorter, have lower fibre content, and have lower above-ground biomass than cultivars developed specifically for fibre production. Linseed production is the dominant flax product in western Canada and fibre is a co-product of oilseed production. The objectives of these studies were to evaluate the effects of northern European fibre flax production practices under western Canadian soil and climatic conditions. A number of cultivars in narrow band and solid-seeded planting geometries to determine if they had similar responses. When flax was planted at recommended seeding rates for linseed production, seed and fibre yields were not affected by planting geometry. Increasing the seeding rate from 40 to 120 kg ha Á1 did not affect seed yield regardless of location or seeding date. Even though fibre content was not affected by seeding rate, higher seeding rates increased stem numbers, decreased stem size, reduced the variability in stem size and increased fibre yield. Delaying planting until the end of May increased fibre yields by an average of 35% with no corresponding decrease in seed yield. Since the relative seed and fibre yield responses of a wide range of cultivars were similar with solid seed and narrow band planting geometries, plant breeders can effectively select for higher fibre producing lines using narrow band seed openers using row spacings up to 30 cm apart.Key words: Linseed, row spacing, seeding rate, cultivar, fibre, fibre Irvine, R. B., McConnell, J., Lafond, G. P., May, W. E., Hultgreen, G., Ulrich, A., Stonehouse, K., Chalmers, S. et Stevenson, F. C. 2010. Incidence des pratiques culturales sur le rendement en fibres du lin dans les Prairies canadiennes. Can. J. Plant Sci. 90: 61Á70. Les varie´te´s du lin (Linum usitatissimum L.) couramment cultive´es dans l'ouest du Canada ont essentiellement e´te´de´veloppe´es pour la production de graines. Ces cultivars sont plus trapus et moins fibreux, et ont une plus faible biomasse ae´rienne que les cultivars cre´e´s pour la production de fibres. Les graines demeurent le principal produit tire´du lin dans l'Ouest canadien, les fibres constituant un sous-produit de l'extraction de l'huile. L'e´tude devait pre´ciser l'incidence des pratiques du nord de l'Europe servant a`produire de la fibre de lin en sol canadien, dans les conditions climatiques propres a`l'Ouest du pays. Plusieurs varie´te´s ont e´te´seme´es en bandes e´troites et en culture dense pour ve´rifier comment elles re´agiraient. Quand on se`me le lin aux densite´s recommande´es pour la production grainie`re, la ge´ome´trie de la plantation n'a aucune incidence sur le rendement en graines ou en fibres. Augmenter la densite´de semis de 40 a`120 kg par hectare ne modifie pas le rendement grainier, peu importe l'emplace...