I would say.....No!...how about using compost bags to line the troughs. not forgetting to put plenty of holes in for drainage....

Ouch, no way. Bitumenous paints contain all sorts of toxins which will kill your plants!

I've restored old half barrels and sealed the inside with bitumen - a liquid damp-proof course to be precise. Stank like old rubber tyres. Plants didn't mind a bit.