Vergleichende Bewertung der Ertragsfähigkeit und Faserqualität von Lein (Linum usitatissimum L.), Hanf (Cannabis sativa L.) und Fasernessel (Urtica dioica L.) zur Produktion hochwertiger Industriefasern

In Central Europe flax, hemp, and fibre nettle are generally available for the production of natural fibres for industrial use. However, cultivation of natural fibres is only competitive if growing methods are optimised and if the produced fibre is of high quality. Therefore, productivity and quality of the indigenous fibre crops were compared over a period of two years and the influences of genotypes and environment were examined. So as to gain information about yield and quality during maturation, various samples were taken within the vegetation period. For hemp, the influence of locational factors was scrutinised over a period of one year. Flax, as well as short fibre flax, achieves higher fibre yields than linseed. The seed yield of short fibre flax falls behind that of linseed, but surpasses the seed yield of flax. The fibre yield rises with an increase of seed density. Higher seed density leads to finer fibres and increases the specific tensile strength of fibres. Raising the N-fertilisation does not affect the fibre yield but furthers the risk of lodging, while mechanical properties decrease. The fibre yield rises until the end of flowering. The mechanical properties do not change after blossom, so that the crop can be harvested at the point of capsular maturity. Hemp trials showed no significant deviation in yield at different locations in spite of varying soil quality. Moreover, an increase in seed density and N-fertilisation did not result in higher yields. In contrast, the fibre quality was affected by soil properties, i. e. clay soils lead to a higher strength of fibres compared to sandy soil. Higher seed densities also improve the fibre strength, whereas high N-fertilisation diminishes the mechanical properties of fibres. Both factors have no effect on the yield. Late ripening hemp genotypes produced a higher fibre yield than early ripening varieties. This can be enhanced by a later date of harvest. Early flowering species do not achieve any increase in fibre yield after flowering. With respect to fibre nettles, clones obtain a higher fibre yield than seedlings. By an increase of plant density with up to 5 plants/m² fibre content as well as fibre yield can be considerably enhanced. The fibre yield goes up during the vegetation period. The fibres become finer and more durable, while the mechanical properties of seedlings exceed those of clones. Of all the species looked at, flax shows the highest variability of yield components depending on the year, whereas fibre nettle has the most constant parameters of yield. Fibre nettle, though, shows the highest variability in the parameters of quality. Generally, the cultivation of hemp achieves the highest fibre yield. However, the results of the highestquality flax varieties can be compared to mediocre hemp species. Due to the low fibre content, the fibre yield of fibre nettle falls clearly behind the yield of flax, short fibre flax and even linseed. Taking into account that the fibres differ in their quality, flax, hemp and fibre nettle are suitable for various use, whereby the production of each plant can be optimised for a best outcome.