Light Environment and Phytochrome-Controlled Germination in Piper auritum

Abstract

1. The heterogeneity of the light environment (in time and space) in a tropical rain forest understorey and its effect on germination response of the heliophile tree Piper auritum was studied in the field and the laboratory. 2. In the laboratory we found responses to a range of R: FR (red: far-red) ratios and to the length of exposure to them. Blue light promoted a small effect on germination. Piper auritum germinated even at very low levels of red light (0.005 μmol m −2 s −1 ). 3. In the rain forest R: FR ratios were typically low (0.25-0.41), with sporadic high values. In field conditions, seed germination was controlled by the R: FR ratio during periods of diffuse illumination. Sunflecks had no effect on germination