Does tomato breeding for improved performance under LED supplemental lighting make sense?

Differences in growth have been reported for tomato under LED compared to HPS light, however, it is not clear if breeding specific for LED supplemental light is worthwhile. Therefore, we derived four recombinant inbred line (RIL) tomato populations from parents with contrasting growth responses to different light spectra. These RIL populations were grown for four weeks under supplemental HPS or 95% red and 5% blue LED light in the greenhouse. For one population we also studied fruit production. Plant height and size of the side shoots of the young plants were strongly reduced under LED supplemental lighting compared to HPS in all populations. The adult plants showed shorter internode lengths, less trusses, less fruits, and lower yield of ripe fruits per plant under LED. However, when the unripe fruits at the last harvest day were included, the difference in yield between HPS and LED disappeared, indicating that the plants under LED light were compacter and slower in development, but in the end produced similar yield. We found numerous QTL, but hardly any of these QTL appeared to be significantly LED-specific. Also, we found very significant genetic effects of maternally inherited plastids and mitochondria, showing the importance of using a parental genotype as mother or as father. However, these effects were very similar between the two light conditions. We conclude that our study does not justify tomato breeding programs that are specifically targeted at 95% red and 5% blue LED supplemental lighting.

Automated summary

There are differences in growth between tomato plants grown under LED and HPS light. However, it is unclear if breeding specifically for LED supplemental light is worthwhile. In this study, tomato populations were grown under HPS or 95% red and 5% blue LED light. The results showed that LED supplemental lighting led to reduced plant height and side shoot size in all populations. Adult plants under LED had shorter internode lengths, fewer trusses, fruits, and lower yield of ripe fruits per plant compared to HPS. However, including unripe fruits in the yield calculation eliminated the difference between HPS and LED, indicating that plants under LED were compact and slower in development but still produced similar yield.