## 4 Discussion
### Effect of Border Widths on Irrigation Quality, Grain Yield and WUE  
The mean annual precipitation (2010-2020) during the growth period of winter wheat was about 150 mm in NCP, and the water deficit during the growth period was about 300 mm [29]. It was necessary to implement multiple supplementary irrigation technology to achieve high and stable grain yield [22]. Border irrigation is one of the most commonly used approaches for local farmers to water wheat plants in the NCP. Optimizing border widths according to different irrigation approaches is the key to ensuring high irrigation quality. At present, the corresponding sowing, tillage, land preparation, and harvest equip \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Treatments**} & \multirow{2}{*}{**Spike Number**} & **Grain Number** & \multirow{2}{*}{**1000-Grain Weight**} & \multirow{2}{*}{**Grain Yield**} & **Water** & \multirow{2}{*}{**Water Use Efficiency**} \\  & & **Per Spike** & & & & **Consumption** & \\ \hline \multicolumn{6}{c}{**(\(\times 10^{4}\) ha\({}^{-1}\))**} & **g** & **kg ha\({}^{-1}\)** & **mm** & **kg ha\({}^{-1}\) mm\({}^{-1}\)** \\ \hline G1Q2 & 550.0 a & 30.0 a & 52.6 a & 7635.3 a & 354.4 b & 21.5 b \\ G1Q3 & 527.5 a & 29.3 a & 51.9 a & 7761.6 a & 367.2 a & 21.1 b \\ G1Q5 & 535.0 a & 29.6 a & 52.4 a & 7815.5 a & 360.7 ab & 21.7 ab \\ G2Q2 & 510.8 a & 31.5 a & 51.7 a & 7527.6 a & 330.7 c & 22.8 ab \\ G2Q3 & 548.6 a & 29.9 a & 52.5 a & 8041.7 a & 334.9 c & 24.1 ab \\ G2Q5 & 537.0 a & 28.5 a & 52.1 a & 8386.1 a & 327.2 c & 25.6 a \\  & & & ANOVA & & & \\ Border width & ns & ns & ns & ns & ** & ns \\ Irrigation quota & ns & ns & ns & ns & ** & ** \\ Interaction & ns & ns & ** & ns & ns & ns \\ \hline \hline \end{tabular} Note: ns indicates no significant difference between different treatments at the \(p>0.05\) level; ** indicate significant difference between different treatments at the \(p<0.01\) level. Different letters in the same column mean significant difference at \(p<0.05\). No significant interactive effect of border widths and irrigation levels was observed.  
\end{table} 
Table 4: Yield components, water consumption, and water use efficiency of winter wheat. ment is quite mature in the market. Since 2020, the mechanization rate of crop cultivation and harvesting in China has reached 71%, of which the comprehensive mechanization rate of wheat, rice and corn harvesting has stabilized at 95%, 85% and 90% [30; 31]. It is well-known that plant barriers during the middle to late growth period would significantly reduce the effective spraying radius of micro-spraying irrigation. However, it is still unclear whether the irrigation quality of micro-spraying could be improved by optimizing the design of border widths, which was the low cost of human input and high efficiency of land preparation using mechanized equipment [29]. Previous studies on the effect of border widths on irrigation quality pointed out that the irrigation uniformity coefficient with a 4.0 m border width was significantly lower than that of a 3.0 m border width in the NCP [32]. In east areas of NCP, irrigation amount with a 2.0 m border width was proved least, while its grain yield, WUE and irrigation water use efficiency were the highest, achieving the dual goal of both high yield and low water consumption [33; 34]. In this study, uniformity coefficients of soil moisture distribution decreased with the increase of border widths, while grain yield increased with border widths. This finding was probably related to a heavy rainfall event in the mid-filling period in 2021, which provided sufficient rainwater for wheat root uptake. Spike number, grain number per spike and 1000-grain weight are three major components contributing to grain yields. In this study, 45 mm irrigation quota treatments generated grain yields comparable to 60 mm irrigation quota treatments, indicating that wheat plants can produce similar results at less irrigation quota.