Crossed Effects of Light and Temperature on the Growth and Maturation of Gametophytes in Costaria costata and Undaria pinnatifida

摘要

We examined for differences in the growth and fertility of microscopic stages between Costaria costata and Undaria pinnatifida in crossed temperaturexirradiance (12, 17, 22°CX20, 60 umol photons nrV) and daylengthxirradiance (8, 12, 16, 24 hx20, 60 umol photons m~V) experimental designs. After 13 days in culture, maximum gametophyte growths of the two species were obtained under the following combinations of factors: 17°C x60 umol photons nrV and 24 h daylength><60 umol photons m~2s_l. C. costata gametophytes produced sporophytes about 6 days earlier than those of U. pinnatifida. Sporophyte densities were highest in the 12 h daylength><60 umol photons rrrV combination after 20 days in C. costata (9.7 plants mirr2) and 26 days in U. pinnatifida (9.1 plants mnr2). However, optimal growth conditions for the microscopic sporophytes differed between species: 17°CX60 umol photons rrr2s~' for C. costata, 12°CX60 umol photons nr2s ~' for U. pinnatifida. Thus, C. costata gametophytes grew faster and produced sporophytes earlier than those of U. pinnatifida, even though the haploid gametophytes of the two species responded similarly to environmental conditions. Optimal growth temperatures for the microscopic sporophytes also differed between species.