

I'm certain that nobody has ever tested liquid smoke in their tobacco transplant water. Presumably, it would increase nicotine production earlier in the plant's growth period, and possibly reduce the effects of some pathogens and pests. Testing this would require careful control (no liquid smoke) transplants of the same tobacco variety within the same bed, with some separating distance.
"...sunflowers grown in soil treated with liquid smoke had larger, thicker, and greener leaves and appeared less prone to pests and disease."

Liquid smoke treatments may enhance a plant's natural defenses
Richard Ferrieri never thought a simple bottle of liquid smoke would change the trajectory of his team's research. Originally, Ferrieri and a team of researchers at the University of Missouri focused on studying how soil, saturated by the intense smoke caused by wildfires, alters plant growth...
Bob
EDIT: The research paper (open access)

Treatments with Liquid Smoke and Certain Chemical Constituents Prevalent in Smoke Reduce Phloem Vascular Sectoriality in the Sunflower with Improvement to Growth
Many higher plants possess a physiological organization that is based upon the carbon economy of their parts. While photosynthates are partitioned according to the relative strength of the plant’s sink tissues, in many species there is also a very close relationship between partitioning...
