GARDENPlants and seeds

What is the threshold level where the concentration of carbon dioxide is detrimental to plant growth?

basically how much carbon dioxide is need to harm the a plant. this is in a closed ecological environment. the lab i am doing is with radish seeds. no fake answers please.

I can’t really think of a reason why excessive ambient CO2 concentrations would be bad for plants. Plants require CO2 for photosynthesis and small amounts of oxygen for respiration. Only low CO2 concentrations would limit growth.

However, certain trees growing near a geologic feature (volcanic) have been dieing off from excessive soil CO2 (about 1200ppm) but that mostly because the roots were getting starved of oxygen.

Time lapse fast growing corn, roots and leaves growing