Rays are a game changer for plants. Most all plants will consume ammonia prior to consuming nitrate. It is not a reduction of nitrates, it is more avoiding a nitrate buildup over time due to less ammonia converting through the nitrification cycle. A couple key notes:
1) It would take an unreasonable amount of plants to keep up with a ray bioload.
2) That bioload may actually kill off the plants from too much of a food source.
3) A bacterial colony will only grow to the size of the available food source first, and secondly the size of the available surface area. Plants will weaken a biological filter if enough plants are used to keep with the bioload.
4) Planats may keep up with small consistent bioloads but the large swings in perams from ray feedings etc.. make plants a risky approach unless just done for looks with plants like anubias etc..
A drip system with some plants for aesthetics would yield much better results that heavy planting.