In Vitro Growth Responses of Ornamental Bananas

Abstract: Light-emitting diodes (LEDs) have become very popular for the production of horticultural
crops. LEDs represent an alternative lighting source to regular fluorescent (FL) bulbs, increasing
the quality of plants and minimizing production costs. LEDs also provide selective light intensity
and quality, suitable for commercial micropropagation. The objective of this study was to evaluate
the growth and development of in vitro ornamental bananas under different light sources. Two
ornamental banana varieties were selected for this study: Length and biomass of plantlets were greater
under LED-1 compared to FL but not significantly different from LED-2. The fresh and dry weight of
shoots and roots, number of leaves, and number and length of roots were not significantly different
between treatments. Chlorophyll content was greater under LEDs. Leaf number and stomata number
and size were greater under FL. Our results indicate that shoot length and biomass could be improved
by optimizing light quality and intensity. Different responses to light sources between the two banana
varieties also indicated a genotype effect.
Keywords: banana; micropropagation; light intensity; light quality; plant growth and development;
leaf anatomy

1. Introduction
Light is one of the primary factors that affect in vitro plant morphogenesis [1,2].
Artificial light sources, including fluorescent lamps, high-pressure sodium lamps, metal
halide lamps, and incandescent lamps, among others, have been widely used for plant
tissue culture research and commercial micropropagation of several crops [3]. Cool-white
fluorescent lamps remain the most used type of light source for micropropagation [4,5].
While popular, cool-white fluorescent light sources have a wide spectrum distribution
(350 to 750 nm) and therefore are of low quality for promoting plant growth. In addition,
energy consumption is increased, representing the second-highest cost in micropropagation
after labor [6,7]. Fluorescent lights also emit heat, which can cause damage and photo-stress
to plants [3]. Therefore, more efficient and cost-effective light systems that promote in vitro
plant growth and development are necessary. Light-emitting diodes (LEDs) have become
very popular in agriculture, particularly for the production of horticultural crops, and have
been widely used in microgravity studies aiming at space life support systems [8,9]. More
recently, LEDs have been incorporated into in vitro plant systems [10]. LEDs represent an
alternative lighting source to regular fluorescent bulbs, increasing the quality of in vitro
plantlets and minimizing the per plant production costs. LEDs provide selective light
intensity and quality, are suitable for commercial micropropagation, and also allow the
control of photosynthetically active radiation (PAR), providing optimal conditions for
plant growth and development, including improved morphology and metabolism.