Re: Aquatic Plants Digest V1 #342
Frank you wrote
> Subject: Re: adjusting daylength (to flower horemanii)
> For anyone who has experimented with artificial light to change daylength in
> order to flower plants (as per discussion for E. horemanii), how important
> is the annual cycle?
This is entirely species and genus specific
> - - When a short day (e.g. 8-hours) is needed for flowering, is a
> complementary long day followed by transition periods needed?
No it is only the night length that is important. Some plants require
only a single long or short day to initiate flowering and some require a
defined period of time at that day length. It also may be linked to
temperture as well. Some plants will also not flower unless both the day
length and the temp are in the correct range. Also you need to watch out
for lights switched on during the night a few minutes can destroy the
long night. So if you do this no peeking at the tanks late at night after
the programmed lights have gone out.
> - - Or, can a short day immediately follow a 12-hour day?
A species of grass that is used here for research only requires a single
day to initiate flowering (very handy for them to find genes specificaly
up regulated upon flowering initiation)
> - - In either case, for how many weeks is the short day needed to trigger the
Probably less than a week below the critical level, I can't answer that
one for sure. Eight hours should be sufficient and if that is held for a
week that should also do for a starting point.
> - - And what about concomittant changes in temperature, light intensity, etc
temp see above, light intensity is probably not so important because it
is naturally variable depending upon the specific micro environment of a