This question is about where aeroponic (air root, mist fed) technology is used at commercial scale for planting material production.
- Tomato: Tomato is propagated through true seed or seedlings, not through an underground vegetative structure, so aeroponics is not the standard commercial method for its seed production.
- Capsicum: Capsicum is also raised from seed and transplanted seedlings, without any tuber like structure that aeroponics would specially benefit.
- Potato: Potato seed programs use aeroponics to grow tissue culture derived plantlets with roots suspended in a misted, dark air chamber, letting mini tubers form on the stem base and be harvested several times from the same plant over the season, sharply increasing the number of disease free mini tubers produced.
- Brinjal: Like tomato and capsicum, brinjal is a fruit and seed propagated crop with no tuber forming stage, so aeroponics is not its standard commercial seed technology.
Because potato's planting material is a tuber that forms on an underground stem, aeroponics fits naturally as a way to multiply disease free mini tubers, which is why it is used commercially for potato and not for the other three crops listed.
Let's summarize:
- Aeroponics suspends roots in air and mists them with nutrient solution.
- It is used commercially in potato to produce large numbers of disease free mini tubers from tissue culture plants.
So the crop is potato.