Effects of daylength,irradiance and settlement density on the growth and reproduction of <Emphasis Type="Italic">Undaria pinnatifida</Emphasis> gametophytes |
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Authors: | Email author" target="_blank">Han?Gil?ChoiEmail author Young?Sik?Kim Soon?Jeong?Lee Eun?Jeong?Park Ki?Wan?Nam |
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Institution: | (1) Faculty of Biological Science and Research Institute for Basic Science, Wonkwang University, Iksan, Jeonbuk, 570-749, Korea;(2) School of Marine Life Science, Kunsan National University, Kusan, Jeonbuk, 573-701, Korea;(3) Department of Marine Biology, Pukyong National University, Busan, 608-737, Korea |
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Abstract: | The effects of daylength, irradiance and spore settlement density on the growth, maturation and sporophyte production of Undaria pinnatifida (Harvey) Suringar gametophytes were examined using a factorial experimental design in culture. The growth of Undaria gametophytes increased with increasing daylength (8, 12 and 16 h), but the maximum fertility occurred at a daylength of 12
h followed by 8 and 16 h. Gametophytes grew better at the 16 h daylength under the same mean daily irradiance (MDI) of 20
μmol photons m−2 s−1. However, the fertility was higher at the short daylength (8 h), indicating that the maturation of U. pinnatifida gametophytes is influenced by daylength rather than by the MDI. Vegetative growth and sporophyte production of gametophytes
were better at 60 μmol photons m−2 s−1 than at 30 μmol photons m−2 s−1 under a 8:16 h LD (Light: Dark) cycle, and their growth and maturation were density-dependant in 16 and 12 h daylength, respectively.
These results suggest that the U. pinnatifida gametophytes require a certain amount of light for the growth and reproduction, and intraspecific competition occurred under
the optimal growth and maturation conditions. However, the sporophyte recruits per unit has been enhanced with increasing
spore settlement density at 8 and 12 h daylengths indicating that high settlement density gives a benefit for maintaining
population, even though the sporophyte production of each female plant is inhibited. In conclusion, the vegetative growth,
reproduction and sporophyte production of U. pinnatifida gametophytes are retarded at a low irradiance above growth saturation and a high settlement density, and are determined by
daylength. |
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Keywords: | gametophytes growth light settlement density reproduction Undaria pinnatifida Phaeophyta |
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