Perhaps we have clarified a bit about the timing of tobacco plants beginning to flower. This possible insight comes from a study of the weed,
Arabidopsis thaliana, which has replaced tobacco in basic botany research. [Nobody will fund anything having to do with tobacco these days.]
The revelation is the result of the stunningly unremarkable discovery that
indoor artificial lighting and temperature control are not natural. Doh! We now have a couple of decades of laboratory data on
Arabidopsis, including all sorts of detailed genetic and enzymatic interactions and effects, but nearly all of the research was undertaken using the very same "standardized lighting and temperature" conditions. That makes for tidy comparisons.
In the discussion in the link below, a small number of adventuresome researchers finally got around to comparing indoor-grown and outdoor-grown
Arabidopsis. They looked at the activity of a particular gene that is known to influence the transition between vegetative growth and flowering, then looked at the possible causes for the differences they documented.
https://phys.org/news/2018-09-morning-gene.html
I'll just get directly to the
punchline:
- standardized "daylight" fluorescent lighting has a different spectrum from sunlight, and this influences the amount of activity of a gene that can trigger flowering
- daily cycling of growing temps--to mimic outdoor conditions--results in a different time of day during which this gene is most active
In my own tobacco seedling production, the trays are on wire shelves on my back porch, and exposed to natural sunlight and day/night cycles. Although the porch temperature is not the same as outdoor temp during the early spring, it does cycle somewhat during the day/night cycle. I have seldom experienced significantly early tobacco blossom formation.
So, no direct answers here. But some of our confusion may be the result of the complex interactions between
- different light spectrum
- different day/night lighting cycles
- different ambient temperatures
- different ambient temperature day/night cycles
And everybody's seedling production conditions are different from everybody else's.
Bob