Answer: The limiting factor of a desert biome is its 10 cm of annual rainfall.
A desert is a biome which receives less than 10 inches of rainfall per annum and has no or sparse vegetation.
In ecological terms, the limiting factor refers to any natural resource or condition which limits the population size. The rainfall received by a desert biome is very less and the water received as precipitation either gets evaporated or gets frozen in hot and cold deserts respectively. Very few plant and animal species can adapt to such harsh conditions for their survival.
Therefore, water becomes a limiting factor of a desert biome apart from the extreme temperatures and food scarcity.