Would a plant need light if the chemicals gained by photosynthesis were given through the roots or as a foliar spray?

I doubt this would work for the vast majority of plants. I think it would cause root rot as the microorganisms in the soil would out-compete the plant. Also the transport systems of the plant might not be efficient in this direction.

I mean might there be a plant somewhere where this might work? Sure. Fungi that grow in the dark would be a lot like such plants, so its biologically possible. There might be a primitive plant that doesn't need its chloroplast to be active to live. I've never heard of one and wikipedia is not helping here...