Flowering of Sturt's Desert Pea ('Swainsona formosa') is Affected by Changes in Glucose Concentration in Shoot Apices

Abstract

Sturt's desert pea ('Swainsona formosa') is an Australian native legume used as an ornamental pot plant and is also suitable for hanging baskets and as a cut flower. One of the impediments to the commercialisation of S. 'formosa' as a pot plant is its inability to produce flower under low light conditions. The work reported here investigated the effect of high light intensity (800 ± 50 μmol m⁻²s⁻¹) and low light intensity (150 ± 10 μmol m⁻²s⁻¹) on the flowering of 'S. formosa' with particular emphasis on the changes of glucose concentration in shoot apices from the vegetative to floral stages. Plants grown under high light initiated flowers within 45 days from seed germination, while plants grown under low light intensity remained vegetative and produced no flowers during the 60 days of experimental period. Using HPLC, trace amounts (0.52 mg g⁻​¹) of glucose were detected under high light intensity at the beginning of transition from vegetative to floral stage (40 days after germination) which increased to 2.70 mg g⁻​¹ with progressive floral development. No glucose was detected in shoot apices of plants grown under low light during the experimental period. Results indicate that adequate glucose production may be required for floral initiation and development in 'S. formosa'.