## 5 Conclusions  
In this study, the effects of the cultivation system of the MRDR system on solanaceous vegetables in the Huang-Huai-Hai Plain of China were evaluated by making comparisons with those of the TR system. The 2 ZBX-2A compound vegetable transplanter for the MRDR system, which can finish the transplanting operation in one pass, was also developed. The main conclusions were as follows:  
1. A vegetable transplanter, the 2 ZBX-2A model, for a mulched ridge with a double row was designed and optimized by using the human-computer interaction method and the discrete element method according to the agronomy requirements of the new cultivation system.
2. The uniformities of the plant spacing and depth in the MRDR system were significantly (\(p<0.05\)) higher than those in the TR system due to the use of the newly designed equipment. The plant-to-plant uniformity makes the MRDR system more competitive. As a result, the fresh fruit yield of the eggplant in the MRDR system increased by 40.8% (\(p<0.05\)) compared to that in the TR system, while the average capsicum yield in the MRDR system was 35.3% higher than that in the TR system.  
Figure 10: Fresh yields of eggplant and capsicum under the MRDR and TR cultivation systems. Note: means of the same crop within a column followed by the same letters are not significantly different at \(p=0.05\).  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Solanaceous** & **Treatments** & **Rainfall \(p\)/mm** & \
\begin{tabular}{c} **Soil Water Content** \\ **Change \(\Delta\) S/mm** \\ \end{tabular} & **Irrigation \(I\)/mm** &
\begin{tabular}{c} **Water Use Efficiency** \\ **WUE/kg\(\cdot\)ha\({}^{-1}\cdot\)mm\({}^{-1}\)** \\ \end{tabular} \\ \hline Eggplant & MRDR & 496.8 & 29.9 a & 155 & 138.5 a \\ TR & 496.8 & 31.6 a & 168 & 86.7 b \\ Capsicum & MRDR & 496.8 & 27.7 a & 149 & 99.0 a \\ TR & 496.8 & 26.8 a & 165 & 63.9 b \\ \hline \end{tabular}
\end{table}
Table 5: Water use efficiency for eggplant and capsicum under the MRDR and TR cultivation systems. Note: means of the same crop within a column followed by the same letters are not significantly different at \(p=0.05\).  
The WUE was 59.7% and 54.9% significantly (\(p<0.05\)) higher under the MRDR system than the TR system for the eggplant and capsicum, respectively, in the field experiment.  
The results of this research indicate that the MRDR system has the potential to improve the yields and WUE of eggplant and capsicum in the Huang-Huai-Hai Plain. Most scholars have studied the effects of the TR system on the transplanting of vegetables, and the results of the MRDR cultivation system on direct seeding are also positive, but there is less research on the relevant cultivation methods and applicable tools of the cultivation mode of MRDR on vegetables. Therefore, this paper carried out preliminary research, which has specific research significance. For further research, the authors will investigate the density of a mulched ridge with double-row planting; that is, the authors will investigate the effects of different ridge spacings, row spacings, and plant spacings on the final yield.  
Conceptualization, T.H. and H.L. ([PERSON]); Methodology, S.S.; Machine design, T.H.; Parameter optimization, Y.S.; Field experiment, X.L. and H.L. ([PERSON]); Validation, J.Z.; Data curation, S.S.; Writing--original draft preparation, H.L. ([PERSON]); Writing--review and editing, T.H.; Supervision, S.S.; Project administration, W.J.; Funding acquisition, H.L. ([PERSON]). All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China (Grant No. 32201683), Opening Foundation of Huang Huai Hai Key laboratory of Modern Agricultural Equipment by Ministry of Agriculture and Rural Affairs of China (Grant No. NJY2022 QN05), and the Shandong Tobacco Industry technology system.  
Not applicable.  
The authors declare no conflict of interest.