Light Intensity Effects on Meadowfoam Growth and Flowering

Date of flowering influences meadowfoam (Limnanthes alba Hartweg ex Bentham) adaptation, economic yield, and management. The objective of this experiment was to determine the effects of photosynthetic photon fluxes (PPF) before and after photoperiodic floral induction (PF1) on meadowfoam growth and flowering. ‘Mermaid’ growth and flowering responses to PPF of 150, 300, 450, 600, 750, and 900 μmol m⁻² s⁻¹ were investigated in a controlled environment. Treatments were initiated either 24 d before or at PF1. Increasing PPF, both before and at PF1, reduced days to first flower, flowering duration, total flowers produced per plant, flowers with bad stamens, and plant height and dry weight at maturity. More flowers were produced when PPF treatments were initiated 24 d before PF1 compared with those initiated at PF1. Light intensities 600 μmol m⁻² s⁻¹ after PF1 enhanced flowering and maturity, and decreased plant size, flower number, and duration of flowering. After PF1, 450 to 600 μmol m⁻² s⁻¹ PPF appeared optimum for a balance of flower production and plant growth in controlled environments. Higher PPF before PFI, however, may increase the potential number of flowering stems and flowers, but it did not substitute for long daylength required for floral induction. Results suggest that in western Oregon low light intensity during fall and winter months may contribute to excessive vegetative growth of Mermaid meadowfoam at the expense of seed production. Oregon Agric. Exp. Stn. Tech. Paper no. 10071.