effect of time of sowing, seed rate and nitrogen level on the fibre yield and quality of flax (Linum usitatissimum L.)

Field plot experiments were carried out in Northern Ireland from 1982 to 1984 to determine the effects of sowing date, seed rate and nitrogen level on the fibre yield and fibre quality of flax. Sowings on 12 April 1983 (cv. Hera) and 26 April 1984 (cv. Belinka) produced higher straw and fibre yields and had higher fibre quality than earlier or later sowings. Field establishment was sensitive to the soil conditions following sowing. The straw yield, total fibre yield and incidence of lodging increased with plant density and to a lesser extent with nitrogen level. Fibre fineness and quality was enhanced at higher plant densities, but the fibre became coarser at higher nitrogen levels although this had only a slight effect on overall quality. It was concluded that flax should not be sown before there is a likelihood of good soil conditions for several weeks after sowing and that plant counts of about 1800/m² are a suitable compromise between high fibre yield and quality and the risk of lodging. No justification was found for increasing nitrogen level above the 25 kg/ha currently being recommended in Northern Ireland.