Any plant grown outside a soil environment, and in a water solution, is considered a hydroponically grown plant. This type of soil-less gardening has many risks, because you can need to apply trace elements appropriately.
Deficiency: Growth is stunted; lower leaves have a checkered pattern of yellow and green.
Toxicity: Chlorosis, or blotchy leaf tissue due to insufficient chlorophyll synthesis. Growth rate will slow and vigor will decline.
Deficiency: Leaf tissue appears yellow, while the veins remain green.
Toxicity: Excess accumulation is rare but could cause bronzing or tiny brown spots on leaf surface.