Articles
CONTROL OF GROWTH AND FLOWERING IN BANKSIA ASHBYI, LEUCOSPERMUM PATERSONII AND LEUCADENDRON “SAFARI SUNSET”
In all cases active vegetative growth takes place during spring and summer, cessation of elongation at the end of summer, and inflorescence initiation during autumn.
During autumn sprouting, but not elongation of axillary buds, can be forced by pruning in Banksia and Leucadendron.
The ability of a meristem to initiate an inflorescence depends on the shoot growth rate during spring and summer.
Based on shoot growth data it appears that inflorescence initiation in these plants is controlled by the long-short day sequence.
This suggestion was proved to be correct in Leucospermum patersonii, grown under phytotron controlled conditions.
In this case long-days not only influenced the rate of vegetative growth before inflorescence initiation, but also activated the axillary buds, so that the initiation could occur under short-day conditions.
Short-days are needed further during the development of the inflorescence primordia.
Inflorescence development in L. patersonii and B. ashbyi can be accelerated by moderate temperatures, especially during the primordial stage.
The spread of the B. ashbyi flowering over a period of 6 months is due to the stage of inflorescence development at the beginning of winter.
The effects of benzyl adenine and gibberellic acid on Leucospermum inflorescence development and on Banksia shoot growth are reported and concidered from the standpoint of controlling the flowering period.