Impact of the seeding rate on flax stem stability and the mechanical properties of elementary fibres

• This work is an innovative study on the impact of flax seeding rate on plant stability.
• A drastic evolution of fibre length and stem diameter was highlighted.
• High seeding rate induces a drop on fibre mechanical performances.
• The plant lodging stability is affected for high level of plant density.

Cultivation of flax fibres (Linum usitatissimun) for composite reinforcement must provide fibres with good mechanical properties, but also a high fibre yield and lodging stability in order to ensure a stable and satisfactory income for the farmer. This work proposes a study of the impact of the seeding rate on these key parameters. We studied the Aramis variety with 4 different seeding rates (1200, 1500, 1800 and 2500 seeds/m2). The results indicate the significant impact of the seeding rate on the stem’s morphological parameters; its increase induces a progressive decrease of the scutched fibre length and of the stem diameter. At the same time, the higher seeding rates obtained improved the scutched fibre’s yield (+11% between 1200 and 2500 seeds/m2) but, conversely, induced a drop in the elementary fibre’s tensile properties and in the flax stem’s lodging stability, mainly due to the large decrease in the stem’s diameter. This work shows that a compromise must be found to optimize the fibre yield, the mechanical performance and the plant’s stability; it underlines the relevance of using a conventional seeding rate, close to 1800 seeds/m2.