Up to what concentration is carbon dioxide a limiting factor for photosynthesis in low light intensity?

Carbon Dioxide limits photosynthesis at a concentration of around 400 ppm (ambient concentration) in low light.

Explanation:

Limiting factors affect the photosynthetic rate, decreasing the potential amount of carbohydrate made via photosynthesis. Carbon dioxide is essential to this form of biosynthesis- it provides the inorganic carbon that is integrated into carbohydrate molecules.

Carbon dioxide is typically present in the atmosphere at concentrations of 0.04%. Light intensity typically cause stomata to open, and increase CO2 uptake. Higher concentrations of CO2  up to 0.1%, cause dramatic increases in the photosynthetic rate.

Low light, thus means less stomatal opening, and less CO2 uptake. As low light intensity can be limiting, it lowers the concentration of Carbon dioxide at which the rate becomes constant.