There is no scientific reason to assume that plants have the capability to suffer. And different scientists try again and again to look into that. But the cold hard truth is, to feel something you need a somewhat complex nervous centrum that plants simply don't have. The same is true for microorganisms and many other simple lifeforms, btw.

Pigs, cows, chickens, even fish experience pain, stress, fear, etc. very similar to how we experience it. And we people know that, that's why many countries have laws against animal cruelty.