Plant Population Effects on Fibre Hemp Morphology and Production

Abstract This paper reports on a 4-year study into the effect of plant density on the morphology and production of fibre hemp. At high density (180-270 plants m2), strong competition for light early in the growing season promoted internode extension (primary growth) and inhibited increase of stem diameter (secondary growth). In relating plant density to fibre hemp production it can therefore be said that a high plant population favours a high yield of long bast fibres for the textile industry. Demands only for high total yield can however be satisfied by targeting 30-45 plants mr2. This is further supported by results of self-thinning, showing plant loss in 1999 was negligible at low density (30-90 plants m2), while at high density (180 and 270 plants m2) 50% and 60% of the initial stand was lost, respectively. In view of this result, and because of the fact that no significant morphological difference was found between 180 and 270 plants m2, it is also worth to note that when growing for long bast fibres 180 plants m2 should be chosen instead of 270 in order to save seed costs.