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Algae 1999;14(4): 229-235. |
| Effects of Auxin and Thallus Extracts on Growths, Sporulation and Spore Release in Ulva pertusa Kjellman
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| Young-Seok Han, Tae-Jin Han
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Department of Biology, University Inchon
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| ABSTRACT |
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Transformation of vegetative cells into reproductive states in Ulva pertusa blades is known to be strongly controlled by environmental factors. When Ulva discs were grown for 9 days at different IAA concentrations (10 super(-6), 10 super(-5), 10 super(-4) and 10 super(-3M) under white light of 100 μmol·m super(-2)·s super(-2) with a 12:12LD cycle, the growth and sporulation were significantly inhibited at the highest concentrations(10 super(-3)M) while no such effect was found in lower concentrations. Growth rate of Ulva pertusa decreased with increasing concentrations of maternal thallus extracts given into the growing medium. In contrast, the amount of chlorophyll content increased by about 50% in the presence of various concentrations of thallus extracts compared with that of control. The rate of sporulation decreased with increasing thallus extracts concentrations. The time taken for induction of 50% sporulation was 3 days in control, 4 days in 1ml, 5 days in 3ml and 7 days in 6ml of thallus extracts added to the medium. Different photon irradiances caused differences in growth and sporulation rate with time. At 100μmol·m super(-2)·s super(-1), the sporulation rate reached 100% in 4 days whereas discs incubated at 10μmol·m super(-2)·s super(-1) sporulated up to 70% for 8 days. Neither significant growth nor sporulation was detected in the dark.
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| Key words:
growth, IAA, irradiance, sporulation, thallus extracts, Ulva pertusa |
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