Can a dye be absorbed by citrus plants to adjust color of the fruit?

I have always believed that coloring a plant could only be done with a cut stem, roots filter out most if not all the dye if a plant is watered with it?

Searching the internet I have found that some red dyes will go through some roots of some plants, no exact details of dyes though

I was bought a red lemon tree for my birthday... one lemon on it , still yellow label on plant says citrus limon rosso

Unusually for the UK the plant was quite dry so I watered it, just water no feed, no sign of any slow release fertiliser in the pot, placed the plant in a bucket of water , water turned deep red.....very very red! , red enough to stain a piece of paper.....

I have had other plants from this supplier , same labels on them and standard lemons from them have no red color when watering....

So the question is..........

Does anyone else think this very red water was because the lemons never turn red in a lot of conditions .....so an attempt to make it red? ( or am I bad minded? ) ,

and does anyone know if a dye can be used ? what dye / chemical could be used for this?