**2. Materials and Methods**

#### *2.1. Plant Material and Culture Establishment*

Two varieties of ornamental bananas, Musa 'Little Prince' and Musa 'Truly Tiny', were obtained from AgriStarts, Inc. (Apopka, FL, USA). They are dwarf varieties of dwarf Cavendish, with a compact habit and thick dark green leaves. Musa 'Little Prince' has thick trunks and is generally used as an ornamental indoors or as a landscape plant outdoors. Musa 'Truly Tiny' is extremely dwarf and produces the smallest edible fruits in the world. Both are desirable as ornamental plants and commonly produced via tissue culture, and have similar growth rates. In vitro plantlets were established in Murashige and Skoog (MS) culture medium [24] supplemented with benzylaminopurine (BAP; 8.8 μM) and sucrose (30 g L−1). The pH was adjusted to 5.8, and the medium was solidified with agar (agar–agar, Sigma Aldrich Inc., St. Louis, MO, USA) at 8 g L−1. A volume of 50 mL of medium was dispensed into baby food jars, and the medium was autoclaved at 121 ◦C and 20 psi for 20 min. In vitro banana plantlets measuring about 5 cm in height had their leaves and roots trimmed to 2 cm shoot-tips, which were used as explants. Baby food jars with polypropylene lids were sealed with parafilm, and cultures were placed in a growth chamber under controlled environmental conditions of 27 ± 2 ◦C and a 16 h photoperiod at 100 μmol m−<sup>2</sup> s−<sup>1</sup> PPFD. In vitro shoots were subcultured to fresh MS medium at four-week intervals.

#### *2.2. Light Sources*

Three different light sources were evaluated: two provided by LED lighting, LED-1 at 116 μmol m−<sup>2</sup> s−<sup>1</sup> (Philips GreenPower DR/B 3:1 150 43W) and LED-2 at 90 μmol m−<sup>2</sup> s−<sup>1</sup> (Philips GreenPower DR/W 3:1 150 33W); and one provided by fluorescent lighting (Philips 9A fluorescent bulbs 40W) at 100 μmol m−<sup>2</sup> s−<sup>1</sup> (FL). Photoperiod was 16/8 h (light/dark). The spectral energy distribution for the lighting used in this study is shown in Figure 1: LED-1 showed peak emissions at 440 nm and 650 nm (Figure 1A), LED-2 showed peak emissions at 440 nm and 670 nm (Figure 1B); and fluorescent lighting (FL) showed a broader

spectrum with peaks in the green (550 nm), blue (440 nm), and some additional peaks in between (490 nm, 590 nm, 610 nm, and 710 nm) (Figure 1C). The intensity and composition of all light sources were measured using an LI-180 Li-Cor spectrometer (Li-Cor, Lincoln, NE, USA).

**Figure 1.** Intensity and composition of lighting as photosynthetically active radiation (PAR) for the different light treatments in this study: (**A**) LED-1 = 116 μmol m−<sup>2</sup> s<sup>−</sup>1; (**B**) LED-2 = 90 μmol m−<sup>2</sup> s<sup>−</sup>1; and (**C**) fluorescent light (FL) = 100 μmol m−<sup>2</sup> s−1. While both LED lights peak in the red range (660–670 nm) with some blue peaks (440–470 nm), fluorescent light has a broader distribution with peaks in the green (550 nm), blue (440 nm), and some additional peaks in between (490 nm, 590 nm, 610 nm, and 710 nm). Maximum irradiance (mW m<sup>−</sup>2) is shown for each spectrum. Measurements were obtained with an LI-180 Li-Cor spectrometer.

#### *2.3. In Vitro Growth and Development*

Explants from all treatments were evaluated four weeks after in vitro establishment for shoot length, root length and number, plantlet fresh and dry weight, shoot fresh and dry weight, root fresh and dry weight, root length, and number determined. Dry weight was determined by oven-drying plantlets at 70 ◦C until they reached constant weight. Five random plants were selected per treatment.
