**4. Conclusions**

A review of the scientific literature suggests that the success of the splice grafting process increases as the cutting angle increases as long as the union is based on similarities between the stems of the grafting seedlings. However, until now, the success rate based on the interaction between the cutting angle and diameter of the seedling has not been reported.

The present study has concluded that the success of a graft depends to a great extent on the cutting angle and diameter of the seedlings, with disparities or similarities between the seedling sections playing an important role in the success of smaller cutting angles, although the stem diameter shows decreasing importance as the cutting angle increases, with the minimum influence of diameter observed within a cutting angle range of 50◦ and 70◦.

Consequently, using the splicing technique with a cutting angle between 50◦ and 70◦ can lead to a substantial improvement of grafting conditions and techniques and can eliminate, to some extent, the random factor of differences between diameters as well as the pre-selection and matching requirements for sections between seedlings, thereby simplifying the demands for manual, automated and robotized grafting systems.

**Author Contributions:** J.-L.P.-A. conceived and designed the experiments, performed the experiments, collected, analyzed the data and interpreted the results, and developed the manuscript. A.C.-O. conceived and designed the experiments, analyzed the data, interpreted the results, and developed the manuscript. C.-C.M.-G. conceived and designed the experiments and performed the experiments. A.-J.C.-F. provided constructive suggestions on experiment analysis.

**Acknowledgments:** This study was supported by Tenova, Technological Center: Foundation for Auxiliary Technologies for Agriculture. The authors would like to acknowledge to all the employees involved for their contributions to experimental setting and data collection.

**Conflicts of Interest:** The authors declare no conflict of interest.
