Day respiration (Rd) is an important parameter in leaf ecophysiology. It is difficult to measure directly and is
indirectly estimated from gas exchange (GE) measurements of the net photosynthetic rate (A), commonly using the
Laisk method or the Kok method. Recently a new method was proposed to estimate Rd indirectly from combined GE
and chlorophyll fluorescence (CF) measurements across a range of low irradiances.