2018 ASHS Annual Conference

Plant growth and physiology are regulated by light quality, duration and intensity. Light emitting diodes (LEDs) have the potential to be used as supplemental and sole light sources in greenhouses and growth chambers respectively. However, quality of light required by many ornamental plants including petunia and spathiphyllum are still unknown. In this study, we used different narrow bandwidth LEDs to determine specific wavelength of light required by petunia and spathiphyllum. The vegetative cuttings of ‘Petunia x hybrida’ cv ‘Mitchell Diploid’ and two varieties of spathiphyllum, ‘Ty’s pride’ and ‘Mojo’ plantlets were grown under five LEDs; red (660 nm), yellow (600 nm), green (525 nm), blue (450 nm) and white (control) which delivered a photosynthetic photon flux (PPF) of 100 m mol m⁻² s ⁻¹ for 16 hours per day. Maximum plant height was observed under blue light for both petunia and spathiphyllum. The maximum number of flowers and earlier flowering in petunia were observed under blue light. Dry shoot biomass was maximum under blue light while dry root biomass was maximum under red light for petunia whereas under yellow light for both varieties of spathiphyllum. Leaf area was maximum under green and yellow light for petunia and spathiphyllum respectively. Maximum root length was observed under white light for petunia and Ty’s pride and under blue for Mojo. Maximum chlorophyll content under white and red light for petunia and blue light for spathiphyllum. There were no significant differences for leaf number, fresh shoot weight and fresh root weight for petunia whereas leaf number, fresh shoot and root weight were maximum under yellow light for spathiphyllum. Root shoot ratio was maximum under red for petunia and Mojo but maximum under yellow for Ty’s pride. Thus, red and blue light are better for petunia whereas blue and yellow for spathiphyllum propagation and production. This research highlighted the effects of light quality on morphology and physiology of petunia and spathiphyllum and the application of narrow bandwidth LEDs for better quality ornamental plant production in a commercial scale.