Exogenous Cytokinin Induces “Out of Season” Flowering in Protea cv. Carnival

Abstract

<jats:p>The cytokinin concentration in the xylem sap of <jats:italic>Protea</jats:italic> L. cv. Carnival (<jats:italic>Protea compacta</jats:italic> R. Br. × <jats:italic>Protea neriifolia</jats:italic> R. Br.) shoots was determined at regular intervals from 11 weeks before until 10 weeks after spring budbreak. Cytokinin levels were high during the early phases of spring shoot growth. Benzyladenine (BA) at 50, 250, or 500 mg·L<jats:sup>−1</jats:sup> was applied to entire shoots on 22 Feb., 12 Apr., and 22 May 2001 (fall in the southern hemisphere) or only to terminal buds on 22 May 2001 at 500 mg·L<jats:sup>−1</jats:sup>. Most of the terminal buds sprouted and initiated an inflorescence when BA application at 500 mg·L<jats:sup>−1</jats:sup> in May was directed only to terminal buds, whereas lower flowering percentages (0%–35%) were achieved when the entire shoot was treated. After whole shoots were treated with BA in Apr. 2001, between 5% and 45% floral reversion was observed. High flowering percentages of 87% to 93% were recorded when BA was applied at 500 mg·L<jats:sup>−1</jats:sup> to the terminal bud in the dormant state or up to the stage when sprouting buds reached the green point development stage. Later applications were less effective, inducing 42% to 43% inflorescence initiation. The flowering time of BA-induced inflorescences was advanced by more than 2 months compared with flowers that initiated naturally on the spring flush.</jats:p>

Comparative transcriptomics reveals a reduction in carbon capture and flux between source and sink in cytokinin-treated inflorescences of Jatropha curcas L.

“…This might be due to the increased abortion of flowers and also reduction in photoassimilates/photosynthates accumulation (Pan et al 2014;Pan et al 2016). No change was observed in number of leaves surrounding inflorescence following BA application at different intervals (TR15 and TR30) which might be attributed to the fact that the cytokinins are most effective when applied at the early stage of development whereas the surrounding leaves were matured at the time of BA treatment (Hoffman et al 2009). Further, yield parameters such as seed number, seed size and seed weight were recorded (after 80 days of treatment).…”

Impact of Temperature on Autumn- and Spring-initiated Inflorescence Systems within a Biennial Pruning System of Protea ‘Pink Ice’ Cut Flowers

“…commercial importance, further studies should aim to increase and favor the number of these shoots with inflorescences initiating in autumn, to reap the benefit of their desired advanced flowering times. Focus should be placed on the characterization of autumninitiated shoots, together with developing pruning regimes in combination with plant growth regulator applications, to promote inflorescence initiation on the autumn flush (Hoffman et al, 2009). In addition, autumninitiated inflorescences commence development during favorable temperature periods and flower quality is likely to be maintained even under slightly higher temperatures driven by climate change.…”