Effect of Light Intensity on the Morphogenesis of Stevia rebaudiana under In Vitro Conditions

Resumo

A study of the effect of various light intensity (75, 135, 230, and 382 µmol/(m² s)) on the morphogenesis of Stevia rebaudiana (Bertoni) Bertoni in vitro was carried out using a unique LED light source Sun Box (wavelength range of 440–660 nm) developed at the Institute of Automation and Control Processes (Far East Branch, Russian Academy of Sciences). The light spectrum of the Sun Box was close to the solar spectrum. Luminescent light with an intensity of 49 µmol/(m² s) was used as a control. It was shown that the cultivation of plantlets using an LED source with an intensity of 75 and 230 µmol/(m² s) promoted the development of plantlets with a combination of morphological and mesostructural parameters important for microclonal reproduction and/or adaptation to the ground. Such plantlets accumulated the maximal weight of the aerial parts and roots, which was especially important for their subsequent transfer into open ground conditions. Plantlets cultivated at a given light intensity with a developed root system would pass the adaptation process faster and it, in turn, would reduce the percentage of plant mortality. The use of a composite LED light source with a certain intensity during in vitro cultivation of S. rebaudiana would allow optimization of the growing and propagation of plantlets and would reduce energy costs compared with the use of fluorescent lamps.