Orchids, with their astonishingly stunning flowers, dominate the international floricultural market. They are considered prized assets for commercial applications in pharmaceutical and floricultural industries as they possess high therapeutic properties and superior ornamental values. The alarming depletion of orchid resources due to excessive unregulated commercial collection and mass habitat destruction makes orchid conservation measures an extreme priority. Conventional propagation methods cannot produce adequate number of orchids, which would meet the requirement of these ornamental plants for commercial and conservational purposes. In vitro orchid propagation using semi-solid media offers an outstanding prospect of rapidly producing quality plants on a large scale. However, the semi-solid (SS) system has shortcomings with low multiplication rates and high production costs. Orchid micropropagation using a temporary immersion system (TIS) overcomes the limitations of the SS system by reducing production costs and making scaleup and full automation possible for mass plant production. The current review highlights different aspects of in vitro orchid propagation using SS and TIS and their benefits and drawbacks on rapid plant generation.

Culture medium and light are important factors that affect the process of in vitro propagation of plants. Particularly for orchids, diverse culture media have been evaluated for micropropagation of many species and hybrids. More recently, light-emitting diodes (LEDs) have become widely used in agriculture, including micropropagation commercial operations, resulting in increased production and reduced costs compared to traditional fluorescent lights. Brassavola nodosa (L.) Lindl. is an orchid, with great potential for commercialization as a potted flowering plant due to the beauty and fragrance of its inflorescences. In this study, we evaluated the effects of culture media (VW, MS, and ½ MS) and light sources (three LED sources and one fluorescent light source) on the micropropagation of B. nodosa orchids. VW medium resulted in the best growth and development of in vitro shoots compared to MS and ½ MS media. Light sources with lower intensity, such as LED-3 (80 μmol m⁻² s⁻¹ PPFD) resulted in the best plant performance in vitro, while LED-2 (1015 μmol m⁻² s⁻¹ PPFD) showed the best plant performance ex vitro. Rooting was obtained in vitro without the need for a rooting phase. Survival ex vitro was 100%, with the successful growth and development of in vitro-derived plantlets during acclimatization.

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: Musa ‘Little Prince’ and Musa ‘Truly Tiny’. Light quality and intensity of three different light sources were evaluated: LED-1 (116 μmol m⁻² s⁻¹), LED-2 (90 μmol m⁻² s⁻¹), and FL (100 μmol m⁻² s⁻¹). 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.

Monstera deliciosa Liebm. ‘Thai Constellation’ is a variegated variety of M. deliciosa belonging to the family Araceae, which has become a new favorite in the foliage plant market. However, limited studies exist on its propagation, and growers have difficulties in achieving large-scale production. This study aimed at developing an efficient protocol for the micropropagation of M. deliciosa using SETIS™ temporary immersion bioreactors. Furthermore, we aimed at evaluating the role of a novel biostimulant (IQ Forte) in the acclimatization of M. deliciosa. Significant differences were observed among the different treatments, showing higher multiplication rates under TIS conditions as compared to the semi-solid control. Adjusting immersion parameters also showed benefits in improving multiplication rates. The novel biostimulant (IQ Forte) did not provide significant gains in growth of M. deliciosa ‘Thai Constellation’ during acclimatization.

Saffron (Crocus sativus L.) is a valuable geophyte plant and one of the most expensive spices in the world. Recently, the demand for saffron spice has increased in worldwide markets owing to its enormous application and value. However, the production of saffron is limited by the vegetative propagation technique and the limited number of high-quality corms planted. Furthermore, climatic changes, notably increasing temperatures, negatively influence saffron multiplication and growth. Thus, it is important to develop alternative cultivation and propagation techniques for saffron under a controlled environment, which could ensure an increase in saffron yield and avoid the negative impact of climatic changes. The present study aimed to develop an alternative method for vegetative propagation of Crocus sativus under controlled conditions. The effect of different cross-cuttings, including basal cuttings (BCs) and top-to-bottom cuttings (CTBs), was evaluated on shoot, leaf, flower, and daughter corm production. All the growth parameters examined were influenced by the cutting treatment applied. The results showed that the highest number of shoots formed was obtained by BCs and CTBs, with an average of 6.68 and 5.47 shoots per corm, respectively, compared to the control with an average of 2.70 shoots per corm. The cutting treatment positively affected the formation of daughter corms in which, the high mean number of corms recorded was obtained by the BC treatment. Meanwhile, the lower size of the daughter corms was obtained after the cross-cutting treatment. This is the first report that provides an alternative propagation for saffron using a controlled environment, which could help to improve the production of saffron.