The Effects of Temperature and Photoperiod on Flowering of Sturt's Dersert Pea ('Swainsona formosa'), An Australian Native Legume

Abstract

Sturt's Desert Pea (SDP) is a legume native to Australia. This plant has enormous potential as a flowering pot plant, suitable for hanging baskets and as cut flowers, due to its spectacular and striking flowers. Commercial success of SDP relies on consistent production of quality plants. Therefore, the aim of the work reported here is to establish the most suitable environmental conditions for production of plants. The two environmental conditions investigated were temperature and photoperiod. Constant temperatures of 25°C, and differential temperatures of 10°C night and 22°C day, and 18°C night and 30°C day were applied. The experimental plants were set in growth cabinets under 12 hours light and 12 hours dark with light intensity simulating that of natural conditions and ranging from 150 to 900 μmol m⁻²s⁻¹. The highest number of flowers per plant was produced on plants grown under temperature of 18°C night and 30°C day. To determine the effect of photoperiod on flowering, an experiment was conducted in which plants were treated for short days (8 hours light and 16 hours dark), neutral days (12 hours light and 12 hours dark), and long days (16 hours light and 8 hours dark). The temperature was set at 18°C night and 30°C day. Plants grown under long days produced flowers faster than did other treatments. The highest number of flowers was produced on plants grown under day neutral conditions.