## 4 Discussion  
### Effects on Population Features of Alfafla  
The plant heights of AM were the lowest in the monocultures during the growing period compared with WM and LM, and consistent differences emerged in the mixtures (Table 3). This finding implies that variety was a determinant of the plant height of alfalfa, as was discovered by [PERSON] et al. (2015) \begin{table}
\begin{tabular}{c c c c c c c c} \hline Treatments & AO1 & AO2 & AS1 & AS2 & WO1 & WO2 & WS1 & WS2 \\ \hline June & \(3.6\pm 0.4\) & \(4.6\pm 0.8\) & \(6.7\pm 1.4\) & \(2.2\pm 0.8\) & \(7.7\pm 1.6\) & \(1.9\pm 0.6\) & \(2.6\pm 0.7\) & \(2.5\pm 0.3\) \\ July & \(10.9\pm 1.7\) & \(4.5\pm 0.7\) & \(3.1\pm 1.0\) & \(4.1\pm 0.8\) & \(5.6\pm 0.6\) & \(2.2\pm 1.1\) & \(4.5\pm 1.0\) & \(5.0\pm 1.4\) \\ August & \(7.0\pm 1.5\) & \(3.9\pm 0.8\) & \(3.8\pm 1.0\) & \(3.6\pm 1.3\) & \(6.7\pm 1.6\) & \(2.9\pm 1.4\) & \(4.5\pm 0.8\) & \(10.6\pm 1.6\) \\ Average & \(7.2\pm 0.4\) & \(4.3\pm 0.6\) & \(4.5\pm 1.1\) & \(3.3\pm 0.4\) & \(6.7\pm 0.7\) & \(2.3\pm 0.3\) & \(3.9\pm 0.3\) & \(6.0\pm 0.3\) \\ \hline Treatments & LO1 & LO2 & LS1 & LS2 & AM & LM & WM & \\ \hline June & \(6.0\pm 1.2\) & \(9.8\pm 1.0\) & \(5.1\pm 1.2\) & \(2.3\pm 0.7\) & \(3.5\pm 0.4\) & \(3.9\pm 0.7\) & \(4.2\pm 0.7\) & \\ July & \(7.3\pm 1.5\) & \(8.6\pm 1.7\) & \(9.0\pm 0.4\) & \(4.8\pm 1.2\) & \(3.9\pm 0.6\) & \(5.3\pm 0.8\) & \(3.9\pm 0.9\) & \\ August & \(8.1\pm 1.5\) & \(6.1\pm 1.5\) & \(3.8\pm 1.0\) & \(3.4\pm 0.7\) & \(3.8\pm 1.1\) & \(7.3\pm 1.2\) & \(4.5\pm 0.7\) & \\ Average & \(7.1\pm 1.1\) & \(8.1\pm 0.7\) & \(6.0\pm 0.8\) & \(3.5\pm 0.2\) & \(3.7\pm 0.6\) & \(5.5\pm 0.3\) & \(4.2\pm 0.6\) & \\ \hline \end{tabular} Note: data are the means\(\pm\)standard deviation. A, algonquin; L, leafy king; W, WL354 HQ. S1 and S2 represent sudangrass at seeding rates of 45 and 60 kg ha\({}^{-1}\), respectively. O1 and O2 represent oat at seeding rates of 60 and 80 kg ha\({}^{-1}\), respectively. M means monoculture. The abbreviations of treatments are combinations of variety and sowing pattern.  
\end{table} 
Table 5: Productivity stability of all communities during the growing period. Figure 2: The percentage of coverage among all treatments during the growing season (mean \(\pm\) SE). The three columns in each treatment represent the coverage proportion of June, July and August. The abbreviations are the same as above. and [PERSON] et al. [31]. We speculated that the plant height of alfalfa was significantly affected by mixed sowing. At the earlier stage, plant heights were not significantly different among the mixtures for the same variety. However, at the later stage, sudangrass showed a stronger impact on the plant height of alfalfa than oat. These variable results might be attributable to differences in the growth rate of the forages. At the earlier growth stage, when all the species were small, the competitive influences of sudangrass and oat were not significant. However, sudangrass matured early and had higher and broader leaves than oat at the later stage, imposing stronger suppression on alfalfa with a greater light interception. In terms of branch number, mixed sowing had a significant impact on alfalfa at the earlier stage. However, the influence of oat diminished over time, while sudangrass still had strong effects. Sudangrass had a stronger effect on the growth of alfalfa than oat, likely because sudangrass had a higher branching ability with a stronger competitiveness for light capture. Neighboring species began to alter the light interception capacity of the community as the mixture grew [32]. However, no significant difference was obtained among the varieties in monocultures, and this result agreed with those of [PERSON] et al. [33]. The plant densities of alfalfa in the mixtures were not significantly different from each other during the same period, suggesting that mixed sowing did not engender a difference in plant density. The higher plant density in monocultures may be due to the higher sowing ratio of alfalfa.