Quality Aspects in Hemp Fibre Production—Influence of Cultivation, Harvesting and Retting

For hemp cultivar Fedrina 74 we investigated the influence of different sowing dates in 1997 and 1998. The highest yields occurred with early sowing dates, at the middle of April. The pure fibre content of the plants of the last sowing date increased rapidly, reaching the same amounts as earlier sown plants. We measured the influence of harvesting technique and retting duration on strength and fineness. Comparison of the results of the purely visual assessment of the degree of retting with the Near Infrared Spectroscopy (NIRS) results shows a good correlation. The NIRS method can supply a reproducible method of analysis for retting. In 1998 we examined damage to the fibres due to the wet conditions during retting. In 1997 an increase in retting time led to a decrease of fibre bundle width. In the North German region, with high humidity in autumn, early sowing is advantageous. For both years early sowing in combination with early harvesting proved the optimal way to get a good yield and a secure collection of the stems after retting.