UV light or photoinhibition

Rrog said:

Plants have constant repair mechanisms for UV exposure, including the "bulging" (pyrimidine dimer) you mention. This is a hazard for humans, not so much for plants.

I suspect the cloning "drift" people describe occasionally as being attributed to the lack of UV over generations, not the exposure to UV. Over the last buncha years, most indoor grows haven't seen much UV at all.

Click to expand...

I clone under just hps and then add uv in flower. . I and many others ran this plant into i think gen 24... then you have others that have problems after a couple and they have never heard of uv bulbs... i would blame bad clone/grow practice definitely.

Bad practices won't change DNA or gene expression. You need long term threatening environmental pressures to turn genes on and off, generally. Like heat to create the expression of heat shock proteins. Likely something similar with drought, etc. but these are temporary expressions.

This genetic drift described lasts, and I'm not sure is reversible. My inclination is that the lack of UV over generations of a clone might turn a gene on or off. Sometimes. On some strains. Central to this is the testimony that the negative traits are not seen on the same strain raised outside. That's very telling