## 3 Result
### The Effect of Different N Management Practices on Photosynthesis Characteristics  
There was no significant difference in Pn of flag leaves after anthesis under N0 between T and F treatments. However, compared with T treatment, the Pn of F under N1 increased at 0 and 7 d after anthesis. And the Pn of F under N3 treatment significantly increased at 7 and 14 d after anthesis. Especially under N2, the Pn of F treatment increased on all sampling days after anthesis compared to that of T. In addition, under the same N \begin{table}
\begin{tabular}{c c c c c c} \hline
**Year** & **Treatment** & **Grain Yield** & **Spike Number** & **Grain Number per Spike** & **1000-Grain Weight** \\ \hline \multirow{7}{*}{2023–2024} & TN0 & 6964.04 \(\pm\) 28.55 f & 373.33 \(\pm\) 2.31 e & 42.24 \(\pm\) 0.08 e & 48.80 \(\pm\) 0.22 a \\  & FN0 & 6989.93 \(\pm\) 53.04 f & 380.00 \(\pm\) 0.00 e & 41.93 \(\pm\) 0.12 e & 48.92 \(\pm\) 0.22 a \\  & TN1 & 9299.09 \(\pm\) 21.61 e & 511.33 \(\pm\) 2.31 d & 43.70 \(\pm\) 0.26 d & 47.18 \(\pm\) 0.02 b \\  & FN1 & 9698.86 \(\pm\) 87.46 d & 512.00 \(\pm\) 2.00 d & 45.13 \(\pm\) 0.12 c & 47.50 \(\pm\) 0.19 b \\  & TN2 & 11,052.48 \(\pm\) 122.29 e & 585.33 \(\pm\) 231 c & 46.83 \(\pm\) 0.58 b & 44.83 \(\pm\) 0.20 d \\  & FN2 & 12,493.13 \(\pm\) 129.73 a & 650.67 \(\pm\) 4.16 a & 47.33 \(\pm\) 0.31 a & 45.45 \(\pm\) 0.28 c \\  & TN3 & 11,079.95 \(\pm\) 102.93 c & 634.00 \(\pm\) 5.29 b & 46.63 \(\pm\) 0.23 b & 41.65 \(\pm\) 0.34 e \\  & FN3 & 11,356.57 \(\pm\) 31.92 b & 657.33 \(\pm\) 3.06 a & 46.60 \(\pm\) 0.10 b & 41.59 \(\pm\) 0.23 e \\ \hline \multirow{7}{*}{2023–2024} & F-value & \multirow{2}{*}{N0, no N application; N1, N application rate of 150 kg ha\({}^{-1}\); N2, N application rate of 210 kg ha\({}^{-1}\); N3, N application rate of 270 kg ha\({}^{-1}\); T, traditional fertilization method; F, fertigation; R, N rates; M, N application methods. Values followed by a different small letter were significantly different at \(p\leq\) 0.05. Data were presented as mean values \(\pm\) SD (n = 3). \({}^{\star}\) Indicates significance at \(p\) level of 0.05. \({}^{\star}\) indicates significance at \(p\) level of 0.01. \\ \cline{1-1} \cline{2-5}  & & & & \\ \cline{1-1} \cline{2-5}  & R & 713.13 \({}^{\star\star}\) & 336.86 \({}^{\star\star}\) & 83.02 \({}^{\star\star\star}\) & 13.16 \({}^{\star\star}\) \\ \cline{1-1} \cline{2-5}  & M & 3572.08 \({}^{\star\star\star}\) & 2921.27 \({}^{\star\star\star}\) & 316.06 \({}^{\star\star\star}\) & 1247.94 \({}^{\star\star\star}\) \\ \cline{1-1} \cline{2-5}  & R \(\times\) M & 203.14 \({}^{\star\star\star}\) & 29.10 \({}^{\star\star\star}\) & 25.95 \({}^{\star\star\star}\) & 22.40 \({}^{\star\star\star}\) \\ \hline \end{tabular}
\end{table} 
Table 1: _Cont._  
Figure 3: Effect of N management practices on canopy photosynthetic effective radiation interception rate. N0, no N application; N1, N application rate of 150 kg ha\({}^{-1}\); N2, N application rate of 210 kg ha\({}^{-1}\); N3, N application rate of 270 kg ha\({}^{-1}\); T, traditional fertilization method; F, fertigation. Different letters indicate statistically significant differences (\(p<\) 0.05). application methods, the Pn of T and F treatments showed N2 \(>\) N3 \(>\) N1 \(>\) N0 at 7 and 14 d after anthesis. However, the Pn of T and F treatments increased with the increase of N application rate at 21 and 28 d after anthesis (Figure 4a,b). Figure 4: Photosynthetic parameters of wheat flag leaves after anthesis under different treatments. Net photosynthetic rate of flag leaves in 2022–2023 (**a**) and 2023–2024 (**b**); Stomatal conductance of flag leaves in 2022–2023 (**c**) and 2023–2024 (**d**); Transpiration rate of flag leaves in2022–2023 (**e**) and 2023–2024 (**f**); Intercellular CO\({}_{2}\) concentration of flag leaves in 2022–2023 (**g**) and 2023–2024 (**h**). N0, no N application; N1, N application rate of 150 kg ha\({}^{-1}\); N2, N application rate of 210 kg ha\({}^{-1}\); N3, N application rate of 270 kg ha\({}^{-1}\); T, traditional fertilization method; F, fertigation.