## 3 Results
### Effect of the Irrigation System and Variety on the Yield, Yield Components, and WUE of Winter Wheat  
As shown in Table 5, in general, the thousand-grain weight and yield under different treatments in 2021-2022 were higher than those in 2020-2021, but the WUE under the W3 treatment was higher in 2020-2021. In the two-year experiment, the thousand-grain weight of the three varieties increased gradually with the increasing irrigation amount, and the thousand-kernel weight of Hengguan35 was greater than that of Hengmai4399 under each irrigation level. From 2020 to 2021, for the same variety, the difference in the thousand-grain weight among different irrigation systems is not obvious. From 2021 to 2022, the thousand-grain weight and effective spikes of Hengmai28 were higher than those of Hengmai4399 and Hengguan35. The thousand-grain weight of Hengmai28 and Hengguan35 were remarkably greater under the W3 treatment than those under the W1 treatment, but there were no obvious differences among the different irrigation systems of Hengmai4399. The thousand-grain weight of Hengmai28 under the W3 treatment was obviously greater than that of Hengmai4399. The effective spikes of Hengmai4399 and Hengguan35 increased gradually with increasing irrigation, but that of Hengmai28 firstly \begin{table}
\begin{tabular}{c c c c c} \hline
**Treatments** & **Variety** & **Spike Length (cm)** & **Spikelet Number** & **Infertile Spikelet Number** \\ \hline \multirow{3}{*}{W1} & Hengmai4399 & 7.63 \(\pm\) 0.13 aA & 17.33 \(\pm\) 0.09 aA & 2.18 \(\pm\) 0.46 aB \\  & Hengguan35 & 6.80 \(\pm\) 0.20 bB & 16.49 \(\pm\) 0.38 bA & 2.02 \(\pm\) 0.32 aA \\  & Hengmai28 & 7.11 \(\pm\) 0.25 bB & 17.56 \(\pm\) 0.15 aA & 2.02 \(\pm\) 0.09 aB \\ \hline \multirow{3}{*}{W2} & Hengmai4399 & 7.80 \(\pm\) 0.07 aA & 17.65 \(\pm\) 0.26 aA & 2.37 \(\pm\) 0.30 aB \\  & Hengguan35 & 6.91 \(\pm\) 0.22 bB & 16.28 \(\pm\) 0.52 bA & 1.97 \(\pm\) 0.28 aB \\  & Hengmai28 & 7.63 \(\pm\) 0.26 aA & 17.45 \(\pm\) 0.40 aA & 1.77 \(\pm\) 0.15 bC \\ \hline \multirow{3}{*}{W3} & Hengmai4399 & 7.37 \(\pm\) 0.34 aA & 17.22 \(\pm\) 0.30 aA & 3.41 \(\pm\) 0.59 aA \\  & Hengguan35 & 7.43 \(\pm\) 0.32 aA & 16.55 \(\pm\) 0.48 aA & 2.53 \(\pm\) 0.24 bA \\  & Hengmai28 & 7.56 \(\pm\) 0.17 aB & 17.47 \(\pm\) 0.61 aA & 2.51 \(\pm\) 0.12 bA \\ \hline \multirow{3}{*}{W3} & V & ** & ** & ** \\  & W & * & ns & ** \\  & V \(\times\) W & ** & ns & ns \\ \hline \end{tabular}  
* Notes: In the same column of data, different lowercase letters indicate that different varieties of the same irrigation system have significant differences at the \(p\) \(<\) 0.05 level and different uppercase letters indicate that different irrigation systems of the same variety have a significant difference at the \(p\) \(<\) 0.05 level, *: \(p\) \(<\) 0.05; **: \(p\) \(<\) 0.01; ns: not significant, V: variety; W: irrigation treatment, V \(\times\) W: interaction between variety and irrigation system, the same as below.  
\end{table} 
Table 4: Effects of different treatments on the spike traits of winter wheat in 2021–2022. reduced and then increased with increasing irrigation. The grain number per spike of Hengmai4399 and Hengmai28 increased first and then dropped with increasing irrigation. The grains per spike of Hengmai4399 under the W3 treatment were significantly less than those under the W1 and W3 treatments. The grains per spike of Hengguan35 increased gradually with the volume of irrigation. Among different irrigation systems, there was no obvious difference in the grain number per spike. The grains per spike of Hengguan35 under the W3 treatment were notably more than those of the other varieties under the W3 treatment; the difference between the different varieties in the other irrigation treatments did not reach a significant level for the grains per spike. For the same variety, the WUE of the W1 and W2 treatments in 2020-2021 was lower than that in 2021-2022, while the WUE of the W3 treatment was higher in 2020-2021.