TWO SUBSTRATES FOR CUT FLOWER HELICONIA IN SOILLESS CULTURE

Cut-flower production of two Heliconia psittacorum cultivars: ‘Teide’ and ‘Guajara’, was evaluated using two substrates, basalt tuff ("picón" or volcanic lapilli) and coconut fibre, in soilless culture in a climate-controlled greenhouse. Earlier studies using tuff produced satisfactory results, but the present experiments showed that coconut fibre increased flower production by 40 to 45%. The fibre substrate also improved quality in terms of individual stem length and overall weight, and the weight/length ratio was also increased, particularly for ‘Teide’ which has a tendency to produce overlong, thus weaker, stems. However, in the fibre substrate, new shoot production was so great that competition for light eventually caused a significant decrease in flower bud production, resulting in the need to renew the crop annually instead of every two years where tuff is used. Trials are underway to clarify the extent to which the coconut fibre itself is responsible for this excessive vegetative growth.