### 2.10.2.4. Implementation of Photosynthetic Capacity[¶](#implementation-of-photosynthetic-capacity "Permalink to this headline")

Based on [Farquhar et al. (1980)](https://escomp.github.io/ctsm-docs/versions/master/html/tech_note/References/CLM50_Tech_Note_References.html#farquharetal1980) and Wullschleger (1993), we can calculate the electron-limited photosynthetic rate under daily maximum radiation ( \\(W\_{jx}\\)) and the Rubisco-limited photosynthetic rate ( \\(W\_{\\mathrm{c}}\\)) as follows,

(2.10.14)[¶](#equation-10-14 "Permalink to this equation")\\\[W\_{J\_{x}} = K\_{j}J\_{x} ,\\\]

(2.10.15)[¶](#equation-10-15 "Permalink to this equation")\\\[W\_{\\mathrm{c}} = K\_{\\mathrm{c}} V\_{{\\mathrm{c}, \\text{max}}},\\\]

where \\(K\_{j}\\) and \\(K\_{\\mathrm{c}}\\) as the conversion factors for \\(J\_{x}\\) and \\(V\_{{\\mathrm{c}, \\text{max}}}\\) ( \\(V\_{{\\mathrm{c}, \\text{max}}}\\) to \\(W\_{\\mathrm{c}}\\) and \\(J\_{x}\\) to \\(W\_{J\_{x}}\\)), respectively. Based on [Xu et al. (2012)](https://escomp.github.io/ctsm-docs/versions/master/html/tech_note/References/CLM50_Tech_Note_References.html#xuetal2012), Maire et al. (2012) and Walker et al. (2014), we assume that \\(W\_{\\mathrm{c}}\\) is proportional to \\(W\_{J\_{x}}\\). Specifically, we have

(2.10.16)[¶](#equation-10-16 "Permalink to this equation")\\\[W\_{\\mathrm{c}}=t\_{\\alpha}t\_{\\mathrm{c}, j0}W\_{J\_{x}}\\\]

where \\(t\_{\\mathrm{c}, j0}\\) is the baseline ratio of \\(W\_{\\mathrm{c}}\\) to \\(W\_{J\_{x}}\\). We recognize that this ratio may change depending on the nitrogen use efficiency of carboxylation and electron transport (Ainsworth and Rogers 2007), therefore the LUNA model has the modification factor, \\(t\_{\\alpha}\\), to adjust baseline the ratio depending on the nitrogen use efficiency for electron vs carboxylation ([Ali et al. 2016](https://escomp.github.io/ctsm-docs/versions/master/html/tech_note/References/CLM50_Tech_Note_References.html#alietal2016)).

