The "minimal daylength" required to prevent flowering of Arabidopsis will
probably vary depending on the ecotype. My experience with Columbia was that
among plants grown under 12hL/12hD (fluorescent lights, only), only a few out
of perhaps a thousand flowered after 2.5 - 3 months; whereas, when grown under
14hL/10hD, essentially all plants flowered within about 6-7 wks. Rosette
growth seemed to be significantly enhanced under the shorter daylength.
Hope this helps, George Karlin-Neumann (Stanford)