Well - in brief. An experiment has conducted with sucrose (C4) loading to see the carbon mass and altered ratio (delta13C) of carbon Isotopes in C3 plant in a partial resource limit condition (light ~300 umol/m2s). Treatments were control (water) and scrose concentrations. I wonder if there is an easy way to estimate photosynthetic carbon? I have recorded IRGA, light hours with PAR, leaf area etc. I saw a formula Pc = A x leaf area x sunshine duriation x 0.273 x 12?? is this widely accepted? Didn't find a good paper.. any suggestion appreciated.