Effects of different LED light spectra on growth and quality parameters of Tulip (Tulipa spp.)

Tulips (Liliaceae) are ornamental plants found growing all around the world. Although tulips are short-day flowers, they are known to positively respond to light treatments. Light plays an important role in plant growth and development of tulips. Accordingly, in this study, we investigated the effects of different light spectra on growth and quality parameters of two tulip cultivated varieties: Tulipa sp. ‘Ronaldo’ and ‘Apeldoorn’. Three different LED wavelengths were used: 100% yellow (3000 K), 100% blue (455±5 nm) and 100% red (650±5 nm) in these trials. The LEDs were turned on for 2, 4 or 6 hours a day with a 0 hours dark control. ‘Apeldoorn’ tulips bloomed earlier than ‘Ronaldo’ tulips. The results in terms of greater plant height, bud length, flower diameter, flower length, flower stalk thickness, number of leaves and fresh leaf weight were observed in ‘Apeldoorn’ tulips. This outcome can be attributed to the characteristics of ‘Apeldoorn’ tulips. Furthermore, in the variety-treatment interaction, the greater results for flower stalk thickness were observed ‘Apeldoorn’ grown under red and blue LED light, while the greater results for petal number were observed in varieties grown under blue LED light. The greater results for petal fresh weight, petal dry weight, bulb fresh weight, and bulb dry weight were observed in ‘Ronaldo’ tulips. No statistically significant differences were found for bud diameter and leaf dry weight.