Hemp for textiles : plant size matters

Abstract

Fibre hemp (Cannabis sativa L.) may be an alternative to cotton and synthetic fibres as a raw material for textile yarn production in the European Union. The agronomic options to manipulate plant development and crop growth with the aim to optimise hemp long fibre production were investigated. Field trials with factors sowing density, sowing date, harvest time and variety were conducted. Stems were traditionally processed by retting, drying, breaking, and scutching. Following standard protocols, almost 1500 hemp stem samples were analysed. Varieties differ widely in their fibre content, but this thesis shows that when variety and plant size are known, the amounts of fibres, wood, and retting losses are known. The dry weight of the stems at harvest, not the factors underlying this weight, are determinant. In retted stems the dry matter is split-up into fibres and wood in a fixed way. The options to manipulate this ratio by crop management, given variety, are very small and for practical reasons they can be neglected. In fibre hemp two bast fibre types occur. Primary or long fibres are valuable for yarn spinning. Secondary fibres are too short and their presence hampers the production of fine yarns. This thesis shows that the secondary fibre front height increases with plant weight. Although a causal relationship between secondary fibre formation and flowering does not exist, the secondary fibre front is found higher in flowering plants when compared to non-flowering plants of the same height. This is likely to be caused by the higher weight or momentum of flowering plants as compared with non-flowering plants of the same height.Consequently, a harvest before flowering is preferable. This was shown in a greenhouse experiment, in which the short-day response of hemp was used to create size ranges of flowering and non-flowering plants. To produce high-quality raw materials for textile production, short crops should be grown. The options to produce plants with the desired size are manifold. Since sowing density, sowing date, and harvest time do not have an additional effect on the primary fibre content besides the indirect effect through stem weight, any combination of these factors could be chosen to optimize plant size.

The potential of volatile organic compounds for the detection of active disease in patients with ulcerative colitis

“…Finally, the significance of the classification model was assessed using a permutation test with 1000 iterations. 33,34 In the final step, the compounds selected as discriminatory between active and non-active UC (via RFE) were used in unsupervised random forests (URF) 35 to visualise the differences between active UC, UC patients in remission and non-UC colitis patients. The differences between chromatograms of all three groups were demonstrated using principal component analysis (PCA) performed on the proximity obtained from URF.…”

Antioxidant and antimicrobial activity of two standardized extracts from a new Chinese accession of non‐psychotropic Cannabis sativa L.

“…Cannabis sativa L. (Cannabaceae) is one of the most remarkable plant species for its unparalleled versatility in several fields including medical, food and textile. Indeed, in addition to the well‐known therapeutic properties against several diseases (Novack, 2016; Russo, 2017), it is an excellent source of nutrients (Callaway, 2004; Kaul et al, 2008; Prociuk et al, 2008; Smeriglio et al, 2016) and an environmentally friendly raw material for the manufacturing processing (Mutje, Lopez, Vallejos, Lopez, & Vilaseca, 2007) and textile industry (Westerhuis, 2016).…”

Pineapple residues for high quality fiber and other applications : with a case study from Costa Rica

“…Hazarika et al (2017b) have spun PALF yarn at 90 tex subsequently using machines for jute softening, flax carding, jute drawing and apron-draft spinning. As a reference, linen (flax) yarn can be as fine as 15 tex, hemp eventually 25 tex (Westerhuis, 2016). Bottlenecks to valorization options Despite the large amount of biomass available and the need for more environmental-friendly ways to dispose pineapple residues up to date there are no large-scale initiatives to bring any of the identified valorization options described in Chapter 3 to scale.…”