INFLUENCE OF INDUCED DORMANCY AND BULB STORAGE TEMPERATURE ON FLOWERING OF VELTHEIMIA BRACTEATA 'LEMON FLAME'

Veltheimia bracteata is a bulbous indigenous South African plant. Under natural growing conditions in South Africa it is evergreen, and dormancy has to be induced in order to possibly manipulate the flowering date. In the Netherlands, where it is grown as a dormant bulb, dormancy and flowering was influenced by storage temperature during dormancy. Plants of the yellow-flowered cultivar ‘Lemon Flame’ were lifted, defoliated, dried off for three weeks under greenhouse conditions, then stored at constant temperatures of 15 ^oC, 20 ^oC and 25 ^oC as well as under greenhouse conditions for eight weeks, after which the bulbs were planted and grown under greenhouse conditions. Other treatments were the removal of the previous peduncle and defoliation. All non-temperature treatments and storage at 20 ^oC and 25 ^oC retarded emergence of new growth by about three weeks compared to the control, while storage at 15 ^oC retarded emergence by six weeks. The delay of emergence of the inflorescences followed a similar pattern with a delay of nine weeks recorded for the 15 ^oC storage treatment. All the treatments involving lifting of the bulbs showed a 30 to 70 percent inhibition of formation of inflorescences. There was a significant relationship between bulb mass and flowering irrespective of the storage treatment, with the smaller bulbs tending not to flower. There was no statistically significant delay in the date of opening of the first flowers of the inflorescences between the different treatments. Peduncle length and number of florets per inflorescence were reduced by all treatments except the 20 ^oC and 25 ^oC storage treatments. These results differ significantly from those obtained in the Netherlands and indicate that this cultivar reacts poorly to induced dormancy.

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