Yield and quality of bast fibre from Abutilon theophrasti (Medic.) in southwest Germany depending on the site and fibre extraction method

Abstract

Natural fibres are environmentally friendly and therefore often used in the automotive industry as an alternative to glass or mineral fibres. In order to meet the demands of natural fibres for the European automotive market, mainly flax and hemp are cultivated in Europe, but the import of other fibres, like kenaf, is also necessary. To increase the possibilities of fibre use and to reduce the dependency of fibre import, additional fibre plants from European countries could be a solution. An alternative fibre crop with fibre properties described as suitable for high value fibrous applications, could be Abutilon theophrasti (velvetleaf). However, there are no European studies about the cultivation of velvetleaf published. Besides cultivation, economically and ecologically acceptable fibre extraction methods are essential for successful implementation of velvetleaf in Europe.Field trials at three different sites are carried out and, in addition, the effect of water shortage on biomass and fibre yield is investigated. Furthermore, four different fibre extraction methods, known for other fibre plants (chemical and mechanical extraction, water and dew retting) are investigated concerning linear density, breaking tenacity and tensile elongation at break.Over the two experimental years and three different sites, velvetleaf biomass yield varied between 5.2 and 12.8 t ha−1 dry matter (DM), and the fibre yield ranged from 0.7 to 2.4 t ha−1 DM. Additional irrigation significantly increased the fibre yield in 2016 by 29%.Among the different methods for fibre extraction, water retting and chemical extraction by 4% sodium hydroxide solution showed the lowest values of linear density (57 and 58 dtex, respectively). Over all extraction methods, the linear density ranged from 53 to 115 dtex. The highest breaking tenacity was determined for chemical extraction by 0.4% sodium hydroxide solution (52.4 cN tex−1) and water retting (50 cN tex−1).Generally, cultivation and fibre extraction of velvetleaf are possible under the conditions in southwest Germany. Due to the different fibre characteristics of velvetleaf compared to flax, hemp, and kenaf, this plant should be assessed in future research for its applicability as a renewable resource for industrial fibres.