Abstract
Plurizoids of Desmotrichum undulatum (J. Ag.) Reinke, grow into microthalli bearing macrothalli under a wide range of temperature (4 "-30 "C) and light conditions: short day (SD) 1000, 2000, 4000 Lux; long day (LD) 500, 1000, 2000 Lux. At 35 "C microthalli die. It is mainly the temperature which modifies the n~orphological expression of the macrothallus: (1) Higher temperatures (ca 20 "-30 "C) support the development of uniseriate macrothalli; lower temperatures (ca 4 "-16 "C) of pluriseriate ribbon-like thalli; and intermediate temperatures (ca 16 "-20 "C) of proximally pluriseriate and distally umseriate macrothalli.
These morphological expressions form a graded series. (2) Higher temperatures promote the growth rate of macrotalli; the rapid growth is soon overtaken by intense zoidogeneses which ends the vegetative growth of very small microthalli. (3) Temperature influences the time span before the onset of zoidogenesis; the time span varies from ca 1 week at 20 "C to ca 13 weeks at 4 "C. The
result is that at lower temperatures (4 "-12 "C) the final macrothalli size is much larger than at higher temperatures, not withstanding a lower growth rate. Under short-day conditions the onset of zoidogenesis IS advanced, particularly so at lower temperatures. Therefore, the largest macrothalli are formed at lower temperatures and under long-day conditions; this corresponds to late spring in nature. Maximum microthalli length in culture (at 8 "C) was ca 60 cm Such macrothalli conform to the description of Punctaria latifolia also in other respects. Therefore D, undulatum (including D. balticum and D scopulorum) is
thought to be synonymous with P. latifolia. The seasonal occurrence of macrothalli (winter-spring) and the geographic distribution are in accordance with results obtained in culture.
These morphological expressions form a graded series. (2) Higher temperatures promote the growth rate of macrotalli; the rapid growth is soon overtaken by intense zoidogeneses which ends the vegetative growth of very small microthalli. (3) Temperature influences the time span before the onset of zoidogenesis; the time span varies from ca 1 week at 20 "C to ca 13 weeks at 4 "C. The
result is that at lower temperatures (4 "-12 "C) the final macrothalli size is much larger than at higher temperatures, not withstanding a lower growth rate. Under short-day conditions the onset of zoidogenesis IS advanced, particularly so at lower temperatures. Therefore, the largest macrothalli are formed at lower temperatures and under long-day conditions; this corresponds to late spring in nature. Maximum microthalli length in culture (at 8 "C) was ca 60 cm Such macrothalli conform to the description of Punctaria latifolia also in other respects. Therefore D, undulatum (including D. balticum and D scopulorum) is
thought to be synonymous with P. latifolia. The seasonal occurrence of macrothalli (winter-spring) and the geographic distribution are in accordance with results obtained in culture.
| Original language | English |
|---|---|
| Pages (from-to) | 321-335 |
| Number of pages | 15 |
| Journal | Marine Ecology Progress Series |
| Volume | 4 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 31-Mar-1981 |