Résumé
Flax fibres are renewable alternatives to synthetics, backed by well-established supply chains. However, they are vulnerable to prolonged droughts, which threaten their yield, quality and use under future climate scenarios. While drought effects on yields are documented, impacts on technical fibres remain underexplored. Our work provides an illustrative case study of how drought affects the composition and structure of bast fibre elements and impacts fibre extractability at pilot scale. Using a broad set of complementary techniques, we investigated two batches of flax (Damara variety), grown under contrasting water conditions and industrially processed. Our results revealed no major disruption in fibre composition or cell-wall organization under drought, but subtle biochemical and microstructural adjustments. These included enhanced mannans' acetylation and enrichment in hydrophobic n-alkanes, consistent with lower but more tightly bound water evidenced by hygroscopic measurements. Protein biosynthesis also increased, with specific upregulation of proteins involved in cell wall remodelling, defense and stress response. At a macromolecular level, drought-stressed fibres displayed polymers modified compared to control ones,and exhibited more pronounced kink-bands consistent with increased extraction difficulty and reduced yields. Overall, flax largely preserved its structural integrity under drought conditions; however, the minor alterations observed impaired its processability, potentially compromising its sustainable use under future climate scenarios.