Promotion of flowering in waratahs (Telopea speciosissima)

R. McConchie, A. Bokshi, C. Dillon, C.A. Offord, E.W. Hoffman
The profitability of the waratah cut flower industry in Australia is currently limited by unpredictable flowering resulting in uncertain returns. Under natural conditions, floral induction occurs on one- to two-year-old stems, with anthesis occurring the following spring. Over the past five years we have been investigating control of flowering in waratah, to reduce the unpredictability and to extend the current 8-week flowering season. Previous research conducted on Protea 'Carnival' has resulted in successful floral initiation and alteration of the flowering period through exogenous application of the cytokinin benzyladenine (BA) to vegetative buds. The aim of this study was to test whether the application of BA could force flowering on waratah stems less than one year old. Plant material was grown in a commercial plantation at The Oaks, NSW Australia. Immediately after harvest on the 9th October 2014, four plants of 'Starfire' and two plants of the 'Brimstone Passion' were pruned back to the original woody framework removing all green shoots. New vegetative shoots that grew from the woody framework were labelled. On 25th February 2015, when the stems were four months old, half of the new stems on each plant were randomly selected for BA (2000 mg L-1) application to the vegetative bud and the remaining buds were treated with water (control). The bud height and diameter were measured throughout the growing season until flower harvest. For 'Starfire' the BA treatment showed significant floral bud conversion (40%) (P=0.016), compared with 7% conversion for the control treatment. However, the floral conversion for 'Brimstone Passion' was not significant, with only 15% floral conversion occurring on BA treated stems. Treatment with BA on four-month-old stems resulted in a significant increases in the bud size over the experimental period with the control treatment displaying only small increases in bud height and diameter. The results indicate that the use of exogenous applications of cytokinin could be used to promote floral induction in commercially produced cut flower waratahs.
McConchie, R., Bokshi, A., Dillon, C., Offord, C.A. and Hoffman, E.W. (2018). Promotion of flowering in waratahs (Telopea speciosissima). Acta Hortic. 1201, 399-404
DOI: 10.17660/ActaHortic.2018.1201.53
cytokinin, anthesis, floral-conversion

Acta Horticulturae