Selection Criteria for Short-fibre Flax

The industrial utilization of short fibres of Linum usitatissimum L. is advantageous for the environment and conserves natural resources due to savings in the production and waste management process. In 1990 a project was started to breed flax for short fibres in combination with oil production. In field experiments 22 (1990) and 20 (1991) varieties and progenies of earlier crosses, respectively, were tested. Phenotypic variation and linear correlations of parameters characterizing yield and its stability were examined with regard to their suitability as selection criteria. The results were as follows: A total harvest of 3 t/ha of short fibre and oil was produced, most of it fibre. The cross progenies tested in 1991 showed a high genetic potential for the combined use of fibre and oil, but their maturity needs to be synchronized better. Simultaneous selection of short-fibre flax genotypes for fibre content and seed yield on the one hand, or for oil content and fibre yield on the other, seems to be practicable. The plants should not exceed I m in height. Thousand-seed weight and oil content were not correlated in the progenies, thus making it possible to select for small-seeded genotypes.     

Determination of effective diffusion coefficients for gaseous and dissolved organic substances in soil material using a 'stopped elution' method with HPLC and GC

Non-steady-state diffusion of chemicals in soil can be described by Fick's second law using suitable effective diffusion coefficients. In this study a ‘stopped elution’ method was used to determine experimentally these effective diffusion coefficients for gaseous and dissolved substances in dry and water-saturated soil. For this purpose a high-performance liquid chromatography (HPLC) apparatus and a gas chromatograph (GS) were used in combination with soil-filled columns. The method is based on the observed spreading of a substance moving through a soil column. This broadening is the result of several processes, one of which is diffusion. A suitable experimental design permits the separate measurement of that part of the widening caused by diffusion. The measured effective diffusion coefficients were compared with theoretical values calculated using predictive algorithms from the literature. For liquid-phase diffusion the maximum deviation between the calculated and the measured values was 34%. The experimental results for gaseous diffusion showed systematic upward deviation from the calculated Coefficients. This might be caused by the diffusion of molecules in the adsorbed state, a phenomenon that had been neglected in the calculations.