**5. Conclusions**

When moved to and cultivated in a glasshouse having supplementary lighting, light intensities of *100* and *150* had significantly improved qualities of grafted tomato seedlings as compared to light intensity of *50*. However, considering improvement of quality of grafted seedlings, there were no significant differences between light intensities of *100* and *150*. Owing to enhanced photosynthesis, the upregulated gene expression levels of *PsaA* and *PsbA* and the corresponding protein expression levels indicated that light intensity of *100* might be the most suitable supplementary lighting to improve the quality of grafted tomato seedlings. That is, supplementary lighting with a light intensity of *100* would be the best choice to improve the quality of grafted vegetable seedlings when both power consumption and economic benefits are taken into account. This study provides new thoughts on supplemental lighting strategies that might be applied in greenhouses and lays the foundation for further studies on the utilization of light energy during early development stages of tomato seedlings.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2073-4395/9/6/339/s1, Table S1: Sequences of Primers used in the expressions of photosynthesis-related genes.

**Author Contributions:** Conceptualization, B.R.J.; Methodology, B.R.J. and H.W.; Formal Analysis, H.W., J.Z., and J.H.; Resources, B.R.J.; Data Curation, H.W. and J.Z.; Writing—Original Draft Preparation, H.W.; Writing—Review & Editing, B.R.J.; Project Administration, B.R.J.; Funding Acquisition, B.R.J.

**Funding:** This research was funded by Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, and Forestry, Project No.319008-01. H.W., J.Z., and J.H. were supported by a scholarship from the BK21 Plus Program, Ministry of Education, Republic of Korea.

**Acknowledgments:** This study was carried out with support from the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, and Forestry (Project No.319008-01). H.W., J.Z., and J.H. were supported by a scholarship from the BK21 Plus Program, Ministry of Education, Republic of Korea.

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

### **References**


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