Conservation Horticulture: In Vitro Micropropagation and Acclimatization of Selected Florida Native Orchids

Abstract

Florida is home to 106 native orchid species, of which 77 are listed as endangered or threatened by the State of Florida. The Institute for Regional Conservation (IRC) has classified 62 of these species as either critically imperiled, imperiled, or rare in South Florida. Because of lack of endosperm, orchid germination rates are very low in nature, as they depend on an obligate relationship with mycorrhizal fungi for nutrients. Most orchid seeds can be germinated in vitro without the need for specific mycorrhizal fungi. This study aims are to establish a fast and efficient protocol for in vitro seed germination using different nutrient media and plant growth regulator (PGR) combinations, and to optimize seedling acclimatization protocols using different greenhouse media. To determine germination preferences, three different in vitro seed germination media were tested supplemented with PGRs, including 1) Murashige & Skoog (MS) (control), 2) MS supplemented with 1.5 mg/L 6-benzylaminopurine (BAP), and 3) MS supplemented with 1 mg/L BAP and 0.5 mg/L 1-Naphthaleneacetic acid (NAA) on Cyrtopodium punctatum, a state-listed endangered, IRC critically imperiled epiphytic orchid. There was no significant difference amongst the treatments after 2 and 6 weeks of seed sowing culture. To understand post-culture survivorship, two epiphytic and one terrestrial native species (Trichocentrum undulatum, Encyclia tampensis, and Oncidium ensatum) were chosen for the acclimatization study with two commercially available potting substrates (coir, sphagnum). To measure seedling growth rates, phenotypic measurements [leaf number, leaf length, root length, plantlet height, light intensity, pH, and electrical conductivity (EC)] and Soil Plant Analysis Development (SPAD) and Normalized Difference Vegetation Index (NDVI) values were recorded monthly for five months. All media/PGR combinations resulted in an initial high percentage of stage I growth but inhibited Protocorm-like bodies (PLBs) development, suggesting more research is necessary to determine later improvements or detriments to MS basal media with BAP and NAA. Comparing acclimatization media with the three species of orchid chosen for this experiment, neither O. ensatum nor E. tampensis showed a marked preference for sphagnum moss or coir. However, T. undulatum did perform better with coir compared with sphagnum. This research will help botanical gardens and commercial plant tissue culture laboratories to have a better understanding on selection of PGR combinations for in vitro cell culture and acclimatization media on increasing the viability and plant health and decreasing the mortality of endangered plants.

Enhancing Micropropagation of Adenophora liliifolia: Insights from PGRs, Natural Extracts, and pH Optimization

“…Coconut water is widely utilized as a growth-enhancing constituent in tissue culture mediums [45]. Its incorporation into the media has been shown to facilitate organogenesis development, primarily attributed to the presence of gibberellins (GAs) within coconut water.…”

Characterization of mycorrhiza associating with Encyclia tampensis and its effect on plant health

“…During readings, the GreenSeeker TM was positioned approximately 45 cm above the sample plant, targeting the green leaves to minimize background noise. This ensured a consistent eld of view for the center, measuring approximately 11.85 cm in diameter (Khoddamzadeh and Dunn, 2016;Mullin et al, 2022;Souza Costa et al, 2023;Khoddamzadeh and Souza Costa, 2023). Comprehensive data collection on the host tree and orchid included orchid chlorophyll content using SPAD and GreenSeeker TM handheld devices, light intensity, tree height and orientation, leaf count, and root and shoot lengths.…”

“…Orchidaceae is one of the largest and most diverse families of owering plants and contains approximately 25,000 species and over 880 genera worldwide (Mullin et al, 2022). Orchids are also well known for having a wide range of uses such as: ornamental, medicinal, and cultural values (De Stefano et al, 2022;Vendrame and Khoddamzadeh, 2016).…”

“…al., 2023), orchids (Porras-Alfaro, 2007;Mullin et al, 2022), cacao(Khoddamzadeh and Souza Costa, 2023), red shrimp plant(Freidenreich et al, 2019), and cocoplum(Souza Costa et al, 2023). In this context, palm trees emerged as the most promising host tree for reestablishment, displaying high SPAD and NDVI values, along with the presence of suitable OMF and a low count of ascomycetes.…”