# Design and Evaluation of a Shaping and Pruning Machine for Dwarf and Densely Planted Jujube Trees
## 4 Discussion  
The shaping and pruning machine for jujube trees designed in this study is simple in structure and reasonable in overall layout. The adjustment range of pruning height is 600-2200 mm, and the adjustment range of pruning width is 800-1400 mm. This machine can quickly finish the shaping and pruning of branches on both sides and top of jujube trees in one operation. The rate of missed pruning and stubble breakage were 5.46% and 5.10%, respectively. It can achieve the rapid shaping and pruning of large-scale dwarf and densely planted jujube trees and effectively solve the problems of high labor intensity and low efficiency of manual jujube tree pruning. In terms of operational efficiency, compared with the knapsack electric pruning machine designed by [PERSON] et al. [19], the pruning machine for jujube trees designed in this \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Index** & **Max** & **Min** & **Avg.** & **S.D.** & **C.V.** \\ \hline Missed pruning rate/\% & 6.2 & 4.8 & 5.46 & 0.50 & 9.16 \\ Stubble breakage rate/\% & 5.8 & 4.2 & 5.10 & 0.60 & 11.76 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Results of field test. Figure 15: Coverage graph of optimization for response objective function. study obviously reduced the manual work intensity and improved the pruning efficiency. Compared with foreign-designed pruning machines for citrus trees [14] and olive trees [31] the single-motor reciprocating pruning machine for grape designed by Xinjiang Agricultural University [36], and the mulberry pruning machine designed by Anhui Academy of Agricultural Sciences [39], the shaping and pruning machine designed in this study could quickly complete the shaping and pruning of both sides and top branches of jujube trees in one operation, and its operational efficiency was obviously higher. However, those machines only finished the plastic pruning of a single tree at a time. Compared with the form trimming machine for horticultural plants designed by [PERSON] et al. in 2021 [38], this machine had a higher pruning efficiency. It could complete the shaping and pruning of a row of jujube trees in one operation. Meanwhile, the shape of the jujube trees after pruning was uniform, which was convenient for the mechanization of subsequent jujube garden plant protection and harvesting operations and conducive to promoting the full mechanization of jujube garden management. In addition, the design of this machine also took into consideration the agronomic characteristics of jujube hangings on jujube trees and incorporated a removal mechanism for jujube hangings that would remove all jujube hangings on the trees in the process of pruning. In terms of machine performance, compared with the pruning machine for citrus designed by Huazhong Agricultural University (the maximum missed pruning rate of that machine is 10.1%, and the qualified pruning rate is 88%) [35], the missed pruning rate of branches for the pruning machine designed in this study was reduced by 4.64% and the stubble breakage rate, by 6.9%. Compared with the single-motor reciprocating grape pruning machine designed by Xinjiang Agricultural University in 2020 (it could only prune one side of the grape vine, and it had a net cutting rate of 90.66%, i.e., missed pruning rate of 9.34%) [36], the missed pruning rate was reduced by 3.88%, and the pruning performance and adaptability of this machine was better. Compared with the wide-band combination copying pruning machine designed by [PERSON] et al., Shandong Agricultural Machinery Research Institute (with a missed pruning rate of 7.3% and qualified pruning rate of 90.9%, i.e., a stubble rate of 9.1%) [37], the missed pruning rate for the machine in this study was reduced by 1.84%, and the stubble rate was reduced by 4.2%. After pruning, only 5.46% of jujube branches were missed, and only 5.10% of pruned branches broke into stubble. The machine can meet the requirements of jujube pruning agronomy and has characteristics of excellent performance and strong robustness.