Kvalita vlákna a kritéria dvojího využití lněného semena

Fibre quality and criteria of dual-purpose use of linseed (Linum usitatissimum L.)

Kvalita vlákna a kritéria dvojího využití lněného semena

Heinrich Rennebaum, Eckhard Grimm, Kristina Warnstorff und Wulf Diepenbrock

Martin-Luther-Universität Halle-Wittenberg, Institut für Acker- und Pflanzenbau, Ludwig-Wucherer-Str. 2, D-06099 Halle (Saale), Germany

Linseed primarily grown as oil crop is also a source of stem fibres. Utilization of these fibres in composite materials and other non-woven products demands for an evaluation of the mechanical characteristics. This aspect is considered here.

Samples were taken from field trials (Bonn, Germany, 1995-1997). Fibres were isolated mechanically on a laboratory machine (Laborflachsbrecher Flaksy, Bahmer). Stress strain plots were recorded using a universal testing instrument (Universalprüfmaschine 1446, Zwick). Fibre thickness was determined by a two-axial laser micrometer (ODAC 15XY-J, Zumbach). The following data were obtained from the analysis of 11 genotypes. The fibre content of the technical stem (unbranched part of the main stem) was 22.5 - 25.4 %. Fibre thickness and fineness amounted to 0.10 - 0.18 mm and to 6.3 - 16.9 tex, respectively. Modulus of elasticity tested at a grip distance (GD) = 50 mm was 12 - 18 GPa. Tensile strength reached 350 - 600 MPa (GD = 2 mm). Tests at different grip distances reflect the load of different cellular components. Plain breaks through the specimen at GD = 2 mm are mostly correspond to the stability of the secondary cell walls, fraying breaks at GD = 50 mm to that of the pectin lamellae.

Optimum growth of linseed for the use of oil and fibres was found at population densities of 800 seed m-2 and nitrogen supply of 50 - 80 kg ha-1. Selection criteria for the assessment are oil yield, straw yield, the length and fibre content of the technical tem, fineness and tensile strength of fibres. The primary data were standardized (SAS procedure: STANDARD). Three factors were extracted (procedure: FACTOR): A (oil yield and fineness), B (fibre content and tensile strength) and C (length of the technical stem and straw yield). The genotypes were grouped in five clusters by the procedure FASTCLUS. Misclassification was corrected by the discriminant analysis (procedure: DISCRIM). The clustering was found strongly depend on the test year. Three groups of linseed genotypes with graduated suitability for dual-purpose use were identified. 'Atalante' was the best cultivar in this test. 'Lifete', 'Flanders', 'Gold Merchant', 'Bolas' (rp = +2), McGregor and Linetta (rp = +1) were found suitable for a dual-purpose use. Four cultivars ('Lifredo', 'Kreola', 'Ceres', 'Hella') were hardly or not recommended.