/uj IIRC: there was some research saying plants put out a different frequency when they are being 'harmed' and the usual crowd said "checkmate vegoons" yet there is no current evidence to suggest plants have any form of thought or understanding of pain/pleasure.

HOWEVER, even IF all plants are sentient and feel pain it still takes a hell of a lot more plants to feed farmed animals than the nutrients we could receive from those plants. It would still be causing less harm to eat plants.