Hemp (Cannabis sativa L.) for high-value textile applications: The effective long fiber yield and quality of different hemp varieties, processed using industrial flax equipment

Abstract

Industrial hemp (Cannabis sativa L.) has great potential as a sustainable source of textile fiber; yet, to develop a viable European hemp-for-textile chain, agronomic practices and primary processing need optimization to current industrial standards. A straightforward approach is to process hemp using existing, modern equipment for flax (linen). Here we extensively evaluated the quantity and quality of fiber extracted from field-retted hemp stems, scutched on the industrial flax processing line. Varieties from diverse European origin (USO 31, Dacia Secuieni, Bialobrzeskie, Futura 75, Carmagnola Selezionata, Santhica 27 and Santhica 70) were sown in randomized field experiments in Belgium, which has a rich long-standing tradition in high-quality linen production. Biomass yield and the quantity of long fiber processed were assessed across three growing seasons (2017–2019; plot size: 15–45 m2). In 2018, we also determined the quantity of tow (short fiber) and, the quality of long fiber in terms of fiber tenacity and elongation. The quantity of total fiber extracted (i.e. long fiber plus tow) accounted for 36.2% of the initial straw yield, indicating high processing efficiency. Approximately equal amounts of tow and long fiber were extracted. Mean long fiber yield approximated one ton per hectare; yet yield variation between varieties was considerable (range long fiber yield: 0.6–1.4 ton/hectare). Despite significant variation between harvest years in straw yield, the quantity of long fiber extracted held relatively constant. Fiber tenacity of long hemp was overall high and comparable to flax (range: 37.6–45.3 cN/tex). Results indicate that field-retted hemp has potential to be processed into quality fiber on the industrial flax line and, that fiber yield can likely further be improved by genotype selection. Harvest mechanization, focused on the collection of parallel hemp stem portions of appropriate length for the flax scutching line (ca. 1 m), seems warranted to make this approach economically viable. Additional research on the fiber properties following hackling and wet-spinning will be needed to fully explore the potentiality of long hemp as a flax supplement for textile applications.