## 3 Results
### Dynamics of Daily and Accumulated Gross Primary Production--GPP  
Daily and accumulated GPP were greater in Irrigated compared to Rainfed throughout the crop growth. In Irrigated, the maximum GPP accumulation rate (MGAR) (11.92 Kg C ha\({}^{-1}\) d\({}^{-1}\)) occurred at 88 DPP, when the accumulated GPP was 551.38 Kg C ha\({}^{-1}\). In Rainfed the MGAR was 3.29 Kg C ha\({}^{-1}\) d\({}^{-1}\), at 90 DPP, when the accumulated GPP was 166.45 Kg C ha\({}^{-1}\). After reaching the MGAR until the end of the canopy life cycle, the accumulated GPP was also higher in Irrigated (492.2 Kg C ha\({}^{-1}\)) than in Rainfed (73.45 Kg C ha\({}^{-1}\)), which indicates that there was a generalized depletion of the GPP under no irrigation conditions (Figure 3). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multicolumn{2}{c}{a  **Carbon Fluxes**} & \multicolumn{2}{c}{**Sprouting**} & \multicolumn{2}{c}{**Vegetative**} & \multicolumn{2}{c}{**Tuberization**} & \multicolumn{2}{c}{**Tuber Bulking**} \\  & & **Rainfed** & **Irrigated** & **Rainfed** & **Irrigated** & **Rainfed** & **Irrigated** & **Rainfed** & **Irrigated** \\ \hline NEE & Mean & 4.39 (\(\pm\)0.39) & 2.92 & 1.93 & \(-\)1.96 & \(-\)0.03 & \(-\)5.55 & 0.35 & \(-\)3.02 (\(\pm\)0.39) \\  & Max. & 4.13 (\(\pm\)0.37) & 1.95 & \(-\)0.30 & \(-\)7.07 & \(-\)0.52 & \(-\)8.36 & \(-\)0.26 & \(-\)4.82 (\(\pm\)0.44) \\  & & (\(\pm\)0.30) & (\(\pm\)0.30) & (\(\pm\)0.50) & (\(\pm\)0.30) & (\(\pm\)0.50) & (\(\pm\)0.30) & (\(\pm\)0.50) & (\(\pm\)0.28) & \(-\)4.82 (\(\pm\)0.44) \\  & sum & 57.04 (\(\pm\)5.11) & 46.7 & 88.8 & \(-\)76.6 & \(-\)26.0 & 9.567 & \(-\)75.6 (\(\pm\)9.83) \\  & & (\(\pm\)4.80) & (\(\pm\)12.5) & (\(\pm\)13.3) & 0.72 (7.80) & (\(\pm\)21.82) & (\(\pm\)1.82) & (\(\pm\)4.38) & \(-\)75.6 (\(\pm\)9.83) \\ \hline GPP & Mean & \(-\)0.60 & \(-\)1.77 & \(-\)2.06 & \(-\)6.88 & \(-\)3.20 & \(-\)11.3 & \(-\)3.01 & \(-\)8.47 (\(\pm\)0.19) \\  & Max. & (\(\pm\)0.05) & (\(\pm\)0.02) & (\(\pm\)0.09) & (\(\pm\)0.34) & (\(\pm\)0.11) & (\(\pm\)0.37) & (\(\pm\)0.09) & \(-\)11.16(\(\pm\)0.29) \\  & sum & \(-\)7.82 & \(-\)28.28 & \(-\)94.8 & \(-\)268 & \(-\)86.4 & \(-\)529.9 & \(-\)48.2 & \(-\)211.8 \\  & & (\(\pm\)0.75) & (\(\pm\)0.09) & (\(\pm\)1.19) & (\(\pm\)6.02) & (\(\pm\)2.17) & (\(\pm\)13.05) & (\(\pm\)1.14) & (\(\pm\)4.860) \\ \hline RECO & Mean & 4.99 (\(\pm\)0.34) & 4.69 & 3.99 & 4.91 & 3.23 & 5.72 & 3.37 & \(-\)5.45 (\(\pm\)0.20) \\  & Max. & 5.26 (\(\pm\)0.38) & (\(\pm\)0.36) & 4.97 & & & & & & & \\  & & (\(\pm\)0.31) & (\(\pm\)0.31) & (\(\pm\)0.25) & (\(\pm\)0.19) & (\(\pm\)0.21) & (\(\pm\)0.19) & (\(\pm\)0.20) & 5.45 (\(\pm\)0.20) \\  & Max. & 5.26 (\(\pm\)0.38) & 5.06 & 4.97 & & & & & & & \\  & & (\(\pm\)0.36) & (\(\pm\)0.31) & 6.29(\(\pm\)0.16) & 4.26 & & & & & & \\  & sum & 64.9 (\(\pm\)4.36) & (\(\pm\)0.36) & (\(\pm\)0.31) & 6.29(\(\pm\)0.16) & 7.75(\(\pm\)0.16) & & & & & \\  & sum & 64.9 (\(\pm\)4.36) & (\(\pm\)4.89) & 184 (\(\pm\)11.3) & 191.5 & 87.1 & 268.9 & \(-\)53.9 & \(-\)11.62 (\(\pm\)4.96) \\ \hline \end{tabular}
\end{table} 
Table 1: Mean, maximum, and sum of carbon fluxes throughout growth stages at Rainfed and Irrigated. Variations of the half-hourly GPP mean throughout the day and across growth stages were observed on each evaluation site. In Irrigated, there were higher carbon fixing rates through the day (half-hourly GPPs) for all growth stages. Tuberization stage rates increased progressively along the day, reaching a maximum of 1.30 \(\pm\) 0.19 mg CO\({}_{2}\) m\({}^{-2}\) s\({}^{-1}\) between 9 and 13 h. In vegetative and tuber bulking stages, half-hourly GPP maximums (0.83 \(\pm\) 0.37 mg CO\({}_{2}\) m\({}^{-2}\) s\({}^{-1}\) by 0.96 \(\pm\) 0.18 mg CO\({}_{2}\) m\({}^{-2}\) s\({}^{-1}\), respectively) were also found between 9 and 13 h, however, they were not significatively different (\(p\) > 0.05). In Rainfed, half-hourly GPPs were lower in the sprouting and vegetative stages compared to the tuberization and tuber bulking stages.