Influence of varied cultivation conditions on the development of fibres of two fibre hemp varieties

In 1992 and 1993 field tests on the medium-early maturing monoecious fibre hemp variety Felina 34 and the late maturing dioecious variety Kompolti Hibrid TC were performed to test the influence of the factors: spatial arrangement (150, 250 and 350 plants/m(2)) and nitrogen fertilization (in the steps: without N, 60 kg Nma and 120 kg Nma) on the following parameters of fibre quality: primary fibre diameter and wall thickness, fibre tenacity and composition of the fibre portion consisting of primary and secondary fibres. Both varieties developed 7 to 8 layers of primary or long fibres. The layer thickness of the total primary fibres was greater for both varieties in the precipitation rich year 1993 than in the dry year 1992 and also correspondingly greater with Kompolti Hibrid TC than with Felina 34. Also with increasing nitrogen fertilization and lower stand densities were the layer thicknesses increased. The increase of the primary fibre layer thickness was caused by an increase in the primary fibre diameter. The portion of extensively filled primary fibres (higher rating), shown by the total primary fibre population of the corresponding cross section cuts, was for Kompolti Hibrid TC in both test years in total higher and more balanced, while Felina 34 showed, especially in 1992, thinner walled fibres. The highest fertilization level also had a negative influence on the degree of fibre filling. Secondary or short fibres, which for many fields are useless, were observed in Kompolti Hibrid TC especially in 1993. Drawn from the stem dry mass the quantitative analysis resulted in 17,9 to 19,8% primary fibre content and from 5,8 to 6,7% secondary fibre content. The tenacity of the fibre containing bark stripes from the middle of stems of Kompolti Hibrid TC (1993) was significantly different between the three fertilization levels. The highest tenacity was to be observed in the unfertilized level with 75,8 cN/tex and it decreased with increasing fertilization intensity to 69,9 resp. 63,7 cN/tex.