Do the roots of a plant in hydroponics need to be submerged in water?

In hydroponics, plant roots do not necessarily need to be fully submerged in water. Instead, they should be in a nutrient-rich solution that allows for adequate oxygen exchange. Many hydroponic systems, like nutrient film technique (NFT) or aeroponics, provide moisture and nutrients while keeping the roots partially exposed to air, promoting healthy growth and preventing root rot.