Effects of LED light spectrum on morphological traits and mineral element ‎concentrations of grafted and non-grafted tomato seedlings

In this experiment, we investigated impacts of various LED light qualities, including 100% red, 100% blue, 70% red + 30% blue, and 100% white with the same light intensity 75±5 µmol m-2 s-1 for 30 days on the growth and mineral element concentrations in grafted onto ‘Maxifort’ rootstock and non-grafted tomato seedlings. Photoperiod, temperature, and relative humidity of the growth chamber were maintained at 16 h, 25/21±2 °C (day/night), and 95%, respectively. Results showed that the maximum of plant height was obtained in non-grafted seedlings under 100% R light. The maximum of stem diameter was obtained under 100% B and 70% R:30 %B treatments. The maximum of root fresh weight was obtained under 100% W and 70 % R:30 %B treatments, while the maximum of root dry weight was obtained under 70 % R:30 % B light treatment. The maximum of leaf area, shoot and total dry weight were obtained in non-grafted seedlings under 70 % R:30 % B light treatment. In addition, non-grafted seedlings under 100% R treatment had the highest P concentration. The maximum of K was obtained in grafted seedlings under 100% B, 100% R and 70 % R:30 %B light treatments and non-grafted seedlings under 100% W and 70 % R:30 % B light treatments. Grafted seedlings under 100% B had the highest Ca concentration. In addition, the maximum of Mg was obtained in non-grafted seedlings under 100% W treatment. Collectively, our results showed that combination of 70% red and 30% blue light and as well as the use of a powerful rootstock like ‘Maxifort’ could promotes plant growth and mineral element concentrations for tomato seedlings.