Seed germination and early development in seedlings of Noveloa coulteriana (Podostemaceae)

Abstract

Unlike other aquatic plants, in Podostemaceae sexual reproduction is the primary mode of reproduction. Thus, germination and seedling establishment are essential processes in the life history of these plants, as they determine their distribution, survival, and abundance. Few studies have examined germination and early seedling development of the Mexican species of this family. In this paper, we experimentally evaluated the influence of light quality (white, red, far red, and darkness), storage time (three months, six months, and 10 years) and temperature (constant 25°C and alternate 15–25°C) on Noveloa coulteriana germination. Seeds were positive photoblastic, and showed high germination capacity in white and red light treatments (>80%). In contrast to previously studied Mexican podostemads, N. coulteriana seeds are recalcitrant. Seeds were also thermoblastic; germination rate was slower in alternate temperature compared to constant temperature. Additionally, using electron microscopy, we observed ex situ seedling development during one month (until its senescence). Micromorphologically, N. coulteriana seedlings showed the characteristic developmental pattern of the subfamily Podostemoideae, where the embryonic shoot and root meristems are lost. Our results indicate that environmental factors such as light quality or temperature fluctuation modify seed germination of N. coulteriana and may play an important role in the reestablishment of natural populations.