The effect of cultivar and seed density on the production and fibre content of Cannabis sativa in southern England

Interest has increased in Cannabis sativa L. due to renewed demand for natural fibres and deregulation of the crop in the UK. The UK production potential and agronomic requirements of the crop were investigated by growing the cultivars Fedora 19, Felina 34, Futura 77, Uniko B and Kompolti, with a range of maturity and genetic backgrounds, at 200 and 400 seeds m(-2) in a replicated experiment over the period 1994-1995. Adverse seedbed conditions in 1994 resulted in a low percentage of seed producing plants, but under good conditions in 1995 a high percentage of seeds produced plants. Plant densities ranged from 52 to 120 m(-2) in 1994 when little self-thinning occurred. In 1995 plant densities ranged from 160 to 347 m(-2) and were subject to significant self-thinning, particularly at the higher seed density, which reduced the maximum stem population at harvest to 227 m(-2). Cultivar effects on stem density were small. Stem yields between 6.3 and 12.9 t DM ha(-1) and bast fibre yields between 1.3 and 3.5 t ha(-1) were recorded, the later maturing Futura 77 and Kompolti consistently produced the highest yields. Under the conditions of these experiments a stem density in excess of 100 m(-2) was required for maximum yield. Chemical stem analysis indicated that genetic differences had a greater impact on the content of stem bast fibre than stem density. (C) 1998 Elsevier Science B.V.