ISSN:
1432-2048
Keywords:
Blue light
;
Geographical distribution (alga, daylength)
;
Photoperiodism
;
Phytochrome
;
Reproduction (alga)
;
Rhodochorton
;
Rhodophyta
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Six geographical isolates of Rhodochorton purpureum (Lightfoot) Rosenvinge (Rhodophyta, Nemalionales) formed tetrasporangia only in short days at 10°C. For most isolates, the critical day-length increased with latitude of origin from 9.5 h for an isolate from California to 14.5 h for one from Antarctica. Tetrasporangium production could be induced by 9–15 short-day cycles followed by a further 22–28 cycles in long days. A night-break consisting of 1 h of white light in the middle of a 16-h dark period inhibited the short-day response of isolates from low latitudes, but not those from higher latitudes. When a similar night-break was given in the middle of a 14-h dark period, however, the response of all isolates was at least partially inhibited. Night-breaks given at any time in the central 7 h of a 14-h dark period were equally inhibitory. Broad-band red light (0.3–0.4 mmol m-2), given as a night-break, caused 50% inhibition of the short-day response. At a slightly higher photon exposure (0.6 mmol m-2, given as 1 μmol m-2 s-1 for 10 min), narrow-band red (662 nm) and blue (448 nm) light caused similar inhibition, but green (547 nm) and far-red (731 nm) were ineffective as night-breaks. The inhibitory effect of a 10-min night-break with red light could not be reversed by subsequent exposure to an equal photon exposure of far-red light. These results add to the existing evidence that the pigments mediating photoperiodic responses among algae are more varied than those among flowering plants.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00392985
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