Question

​when do the desert plants take up carbon dioxide and perform photosynthesis?

Answer 1

in desert the climate is very hot and and the amount of rainfall is very low....if desert plants take co2 during day....lots of water will be lost....isn't it ? So...to prevent the water loss they take co2 during night....

ISN'T IT SIMPLE ..

Answer 2

The desert plants containing chlorophyll take up carbon dioxide at night.  

The carbon dioxide is then stored and it is the next day in the presence of sunlight that they perform the process of photosynthesis.  

This reason behind this unusual behaviour is the stomata do not open during day time to prevent loss of water by transpiration. Instead, they open at night when temperatures are cooler to absorb carbon dioxide.