Epiphytic Genus Research Articles

A single origin of leaflessness in Afro‐Malagasy angraecoids (Orchidaceae, Angraecinae)

AbstractMicrocoelia and the monospecific Taeniorrhiza and Chauliodon are notable among Afrotropical angraecoid orchids for being leafless. However, the affinity among these genera was not addressed in previous molecular phylogenetic studies, thus precluding the understanding of how many times has leaflessness evolved in angraecoids. The discovery of an additional species ascribable to Taeniorrhiza in Gabon, and a revision of all material referrable to this genus in herbarium collections, created the possibility to investigate the phylogenetic position of Taeniorrhiza relative to Microcoelia and Chauliodon. Based on phylogenetic inference using ITS‐1 and two plastid regions (matK/trnK, trnL‐trnF), and including 20 of the 34 species of Microcoelia recognised prior to our study, we here demonstrate that Taeniorrhiza and Chauliodon are deeply imbedded in Microcoelia, and are thus treated here as synonyms of the last. Accordingly, we describe the novelty from Gabon as a new species of Microcoelia: Microcoelia nguemae sp. nov. The new species is illustrated with colour photographs, and also with line drawings. Its preliminarily IUCN conservation status is provided. The novelty is notable for the dorsiventrally asymmetric distribution of pneumathodes along its roots and for bearing the longest lip spur in this Afro‐Malagasy epiphytic genus. The new phylogenetic framework suggests a single origin of leaflessness in Afrotropical angrecoids and reveals the informative value of the rostellum to reconstruct relationships within Microcoelia. This serves as the basis of a newly proposed sectional treatment for Microcoelia, recognising 37 species, one new section, a new status for the defunct genus Encheiridion and the redefinition of Microcoelia sect. Microcoelia and sect. Brachyglossa.

Beyond Nuclear Ribosomal DNA Sequences: Evolution, Taxonomy, and Closest Known Saprobic Relatives of Powdery Mildew Fungi (Erysiphaceae) Inferred From Their First Comprehensive Genome-Scale Phylogenetic Analyses.

Powdery mildew fungi (Erysiphaceae), common obligate biotrophic pathogens of many plants, including important agricultural and horticultural crops, represent a monophyletic lineage within the Ascomycota. Within the Erysiphaceae, molecular phylogenetic relationships and DNA-based species and genera delimitations were up to now mostly based on nuclear ribosomal DNA (nrDNA) phylogenies. This is the first comprehensive genome-scale phylogenetic analysis of this group using 751 single-copy orthologous sequences extracted from 24 selected powdery mildew genomes and 14 additional genomes from Helotiales, the fungal order that includes the Erysiphaceae. Representative genomes of all powdery mildew species with publicly available whole-genome sequencing (WGS) data that were of sufficient quality were included in the analyses. The 24 powdery mildew genomes included in the analysis represented 17 species belonging to eight out of 19 genera recognized within the Erysiphaceae. The epiphytic genera, all but one represented by multiple genomes, belonged each to distinct, well-supported lineages. Three hemiendophytic genera, each represented by a single genome, together formed the hemiendophytic lineage. Out of the 14 other taxa from the Helotiales, Arachnopeziza araneosa, a saprobic species, was the only taxon that grouped together with the 24 genome-sequenced powdery mildew fungi in a monophyletic clade. The close phylogenetic relationship between the Erysiphaceae and Arachnopeziza was revealed earlier by a phylogenomic study of the Leotiomycetes. Further analyses of powdery mildew and Arachnopeziza genomes may discover signatures of the evolutionary processes that have led to obligate biotrophy from a saprobic way of life. A separate phylogeny was produced using the 18S, 5.8S, and 28S nrDNA sequences of the same set of powdery mildew specimens and compared to the genome-scale phylogeny. The nrDNA phylogeny was largely congruent to the phylogeny produced using 751 orthologs. This part of the study has revealed multiple contamination and other quality issues in some powdery mildew genomes. We recommend that the presence of 28S, internal transcribed spacer (ITS), and 18S nrDNA sequences in powdery mildew WGS datasets that are identical to those determined by Sanger sequencing should be used to assess the quality of assemblies, in addition to the commonly used Benchmarking Universal Single-Copy Orthologs (BUSCO) values.

Morphology and Molecular Phylogeny of a New Marine, Sand-dwelling Dinoflagellate Genus, Pachena (Dinophyceae), with Descriptions of Three New Species.

Marine benthic dinoflagellates are interesting not only because some epiphytic genera can cause harmful algal blooms but also for understanding dinoflagellate evolution and diversification. Our understanding of their biodiversity is far from complete, and many thecate genera have unusual tabulation patterns that are difficult to relate to the diverse known phytoplankton taxa. A new sand-dwelling genus, Pachena gen. nov., is described based on morphological and DNA sequence data. Three species were discovered in distant locations and are circumscribed, namely, P. leibnizii sp. nov. from Canada, P. abriliae sp. nov. from Spain, and P. meriddae sp. nov. from Italy. All species are tiny (about 9-23μm long) and heterotrophic. Species are characterized by their tabulation (APC 4' 3a 6'' 5c 5s 5''' 2''''), an apical hook covering the apical pore, an ascending cingulum, and a sulcus with central list. The first anterior intercalary plate is uniquely "sandwiched" between two plates. The species share these features and differ in the relative sizes and arrangements of their plates, especially on the epitheca. The ornamentation of thecal plates is species-specific. The new molecular phylogenies based on SSU and LSU rDNA sequences contribute to understanding the evolution of the planktonic relatives of Pachena, the Thoracosphaeraceae.

Farming by ants remodels nutrient uptake in epiphytes

True agriculture - defined by habitual planting, cultivation, harvesting and dependence of a farmer on a crop - is known from fungi farmed by ants, termites or beetles, and plants farmed by humans or ants. Because farmers supply their crops with nutrients, they have the potential to modify crop nutrition over evolutionary time. Here we test this hypothesis in ant/plant farming symbioses. We used field experiments, phylogenetic-comparative analyses and computed-tomography scanning to investigate how the evolution of farming by ants has impacted the nutrition of locally coexisting species in the epiphytic genus Squamellaria (Rubiaceae). Using isotope-labelled mineral and organic nitrogen, we show that specialised ants actively and exclusively fertilise hyperabsorptive warts on the inner walls of plant-formed structures (domatia) where they nest, sharply contrasting with nitrogen provisioning by ants in nonfarming generalist symbioses. Similar hyperabsorptive warts have evolved repeatedly in lineages colonised by farming ants. Our study supports the idea that millions of years of ant agriculture have remodelled plant physiology, shifting from ant-derived nutrients as by-products to active and targeted fertilisation on hyperabsorptive sites. The increased efficiency of ant-derived nutrient provisioning appears to stem from a combination of farming ant behaviour and plant 'crop' traits.

Assessment of atrazine decontamination by epiphytic root bacteria isolated from emergent hydrophytes

Aim of the study was to identify atrazine remediating bacteria that can potentially succeed in situ where they encounter varied environmental conditions. Three epiphytic root bacteria, genus Pseudomonas and Arthrobacter, were isolated from rhizoplanes of hydrophytes Acorus calamus, Typha latifolia, and Phragmites karka. Potential of these strains to decontaminate environmentally relevant concentrations of atrazine was determined in liquid atrazine medium (LAM) and Luria-Bertani (LB) medium at varying pH and temperature. There was an increase in decontamination by the strains with time upon exposure to 2.5 to 10 mg l−1 atrazine over a period of 15 days, notably, in both minimal and nutrient-rich media. Growth in terms of O.D.600 and biomass determined during the same period also showed a corresponding surge. Pseudomonas sp. strain AACB mitigated atrazine in a wide range of pH (5 to 8). Pseudomonas sp. strains AACB and TTLB decontaminated > 62% atrazine at 10 °C. All the strains exhibited plant growth–promoting traits in vitro, reported for the first time in the presence of atrazine. Strain AACB exhibits the novel trait of atrazine decontamination under harsh environmental conditions mimicked in lab. Strains isolated in the present study promise success in in situ remediation. Bioreactors and water treatment plants can be designed comprising the hydrophytes and the strains inoculated into their rhizospheres to improve efficacy of the treatment. They can be used to study plant-bacterium mutualistic symbiosis or other interactions occurring during atrazine mitigation.

Hoya species of Belitung Island, Indonesia, utilization and conservation

Rahayu S, Fakhrurrozi Y, Putra HF. 2018. Hoya species of Belitung Island, Indonesia, utilization and conservation. Biodiversitas 19: 369-376. Epiphyte greatly contributing to the forest biomass in the tropic. Heath forest as occurred in Belitung Island, Indonesia is a specific habitat for many endemic species, which are poor in nutrients and very fragile in response to any disturbance. We observed Hoya species-one of the epiphytic genus in the tropic in the heath forest and on other habitats of Belitung Island, Indonesia. Hoya species are plants with promising uses as functional ornamental plants (able to absorb pollutants from their growing environments), and as sources of certain medicinal and pharmaceutical compounds. A survey of Hoya was carried out on Belitung Island, off the southeast coast of Sumatra, in 2015, 2016 and 2017. There are two interesting Hoya species that grow well in the "padang community" of the heath forest, on the island: i.e. H. coronaria Blume and H imperialis Lindl. These two have attractive flower size and color. Another species, H. verticillata (Vahl) G.Don, with less attractive flower color, is distributed in the mixed forest of the beach areas, while H. multiflora Blume and H. scortechinii King & Gamble, also with less attractive flower color, are distributed in mixed forest of upper elevations. The distribution and habitat preference of different Hoya species indicate different requirements for moisture and temperature, which we hypothesize also result in differences in the pollinator species visiting the plants. The "padang community" of the heath forest on Belitung experiences maximum temperatures up to 370C in the afternoon. It is located in an Af climate type, with average rainfall, air temperature and humidity of ± 205 mm/month, 270C and 77.5%, respectively. Hoya coronaria is the most contributing biomass in the heath forest compared to the other Hoya species in the community.

Phylogeny ofCampyloneurum(Polypodiaceae)

Premise of research. Campyloneurum is entirely Neotropical with about 60 generally accepted species. Although a prominent, mostly epiphytic genus in Neotropical forests, no research has been done previously on its phylogeny or character evolution.Methodology. We obtained sequence data from four plastid markers (rbcL, trnG-trnR, trnL-trnF, and rps4-trnS) of 44 species of Campyloneurum, or 73% of the species in the genus. The sequence data were analyzed using Bayesian and maximum likelihood methods. Herbarium specimens were examined to code morphological characters, and spores were imaged with the scanning electron microscope. Growth form and five morphological character states were optimized on the trees using parsimony.Pivotal results. We confirm most previous studies that Campyloneurum forms a clade with Microgramma and Niphidium. The three genera are generally characterized by simple entire leaves, areolate venation, and included veins within the areoles. Within Campyloneurum, seven main clades were rec...

The Epiphytic Genus Gambierdiscus (Dinophyceae) in the Kermadec Islands and Zealandia Regions of the Southwestern Pacific and the Associated Risk of Ciguatera Fish Poisoning.

Species in the genus Gambierdiscus produce ciguatoxins (CTXs) and/or maitotoxins (MTXs), which may cause ciguatera fish poisoning (CFP) in humans if contaminated fish are consumed. Species of Gambierdiscus have previously been isolated from macroalgae at Rangitahua (Raoul Island and North Meyer Islands, northern Kermadec Islands), and the opportunity was taken to sample for Gambierdiscus at the more southerly Macauley Island during an expedition in 2016. Gambierdiscus cells were isolated, cultured, and DNA extracted and sequenced to determine the species present. Bulk cultures were tested for CTXs and MTXs by liquid chromatography-mass spectrometry (LC-MS/MS). The species isolated were G. australes, which produced MTX-1 (ranging from 3 to 36 pg/cell), and G. polynesiensis, which produced neither MTX-1 nor, unusually, any known CTXs. Isolates of both species produced putative MTX-3. The risk of fish, particularly herbivorous fish, causing CFP in the Zealandia and Kermadec Islands region is real, although in mainland New Zealand the risk is currently low. Both Gambierdiscus and Fukuyoa have been recorded in the sub-tropical northern region of New Zealand, and so the risk may increase with warming seas and shift in the distribution of Gambierdiscus species.

Taxonomic and Phylogenetic Placement ofPhaeodimeriella(Pseudoperisporiaceae, Pleosporales)

Abstract Phaeodimeriella is an epiphytic or pathogenic genus that occurs on plant surfaces associated with other fungi and belongs in the family Pseudoperisporiaceae (Dothideomycetes family, incertae sedis). The taxonomy of Phaeodimeriella has been problematic because of lack of molecular data and as some of the important morphological characters having not been reported. The present study clarifies the phylogenetic placement of Phaeodimeriella using fresh collections from northern Thailand. Two Phaeodimeriella species are characterized based on combined analyses of LSU, SSU, TEF and RPB2 sequence datasets. In the phylogenetic analyses, the two Phaeodimeriella species form a distinct lineage, adjacent to the Lentitheciaceae and Bambusicolaceae, in the order Pleosporales. The genus Phaeodimeriella is re-described and illustrated using modern concepts from fresh collections and provided with molecular data. The new species Phaeodimeriella cissampeli and P. dilleniae are introduced based on morphological cha...

Phylogenetic study of the genus Aptychella (Pylaisiadelphaceae, Musci)

Abstract The relationships among species of the epiphytic genus Aptychella (Broth.) Herzog and Clastobryopsis M. Fleisch. were inferred based on phylogenetic analyses of plastid (rpl16, rps4, and trnL-F) and mitochondrial (nad5) gene sequences as well as morphological features. One of the Asian members, Aptychella robusta (M. Fleisch.) M. Fleisch., exhibits much genetic variation and differentiation among populations, which may reflect the presence of cryptic species. The distinctiveness of Asian members characterized by unicostate leaves, A. brevinervis (M. Fleisch.) M. Fleisch., A. pseudobrevinervis H. Akiyama and A. oblongifolia H. Akiyama, are confirmed. On the contrary, Aptychella proligera, the sole member of the genus known from South and Central America, is shown to have a close relationship to the A. brevinervis complex and preserves low genetic variation among samples collected from geographically remote localities. This lack of variation might be caused by a recent immigration from Asian popula...

Zeloasperisporiales ord. nov., and Two New Species ofZeloasperisporium

Neomicrothyrium is an epiphytic genus that forms small black dots on the surface of living or dead fallen leaves, although it rarely causes any damage to the host. Based on its flattened thyriothecia, it was considered that Neomicrothyrium belongs in the order Microthyriales, a group of fungi that is relatively poorly studied. Microthyriaceae- like taxa appearing as small black dots on leaves were collected in Chiang Rai Province, Thailand, and studied using morphological characterization and phylogenetic analyses. As a result of molecular and morphological study, we established that Neomicrothyrium is linked to the asexual genus Zeloasperisporium and that we had collected two new taxa. Two new species, Zeloasperisporium ficusicola and Z. wrightiae are therefore introduced in this study based on morphology and phylogeny. Neomicrothyrium is linked to Zeloasperisporium and is therefore synonymized under the older name Zeloasperisporium. Phylogenetic analyses of combined LSU and SSU rDNA sequence data indicate that Zeloasperisporiaceae belong in the class Dothideomycetes, but clusters with Natipusillales in a distinct lineage from Microthyriales. We therefore introduce a new order, Zeloasperisporiales to accommodate the family Zeloasperisporiaceae. The life cycle of Zeloasperisporium species is remarkable. The sexual morph produces ascomata on the leaf surface and appears to lack any other structures and it is unclear how the ascomata obtain nutrients. The asexual morph produces conidia which can be found on the surface of plants, or in air, but it is also unclear how conidia obtain their nutrients. In this study, isolates from the sexual morph produced asexual morphs in culture.

Reappraisal of Dendroceros cucullatus (Dendrocerotaceae, Anthocerotophyta)

Dendroceros is an epiphytic or epiphyllous genus within Anthocerotophyta, with about 48 extremely specialised species in having endosporic germination (Villarreal et al. 2010; Garcia et al. 2012). Dendroceros difficilis was originally described by Stephani (1917: 1009), based on a collection made by V. Schiffner from Java, Indonesia. Hasegawa (1980) reduced a little-known species D. cucullatus Stephani (1923: 429) from the Philippines, to its synonym. An examination of the holotypes of both species, however, reveals that D. cucullatus is quite different from D. difficilis in thallus margin, structure of costa and epidermal cells of capsule. Dendroceros cucullatus is thus reinstated as a separate species. Based on Schuster’s (1987) treatment, these two species belong to subgenus Apoceros Schuster (1987: 195) based on the cavernous costa in both. Dendroceros difficilis has been described and illustrated by Hasegawa (1980) and Piippo (1993). The following description of D. cucullatus is based on the holotype kept in Geneva Herbarium (G) and recently collections from Thailand.

Gambierdiscus cf. yasumotoi (Dinophyceae) isolated from New Zealand's sub-tropical northern coastal waters

A globular form of the epiphytic dinoflagellate genus, Gambierdiscus, was isolated and cultured from Northland, New Zealand. The closest species, based on Bayesian analyses of the large subunit ribosomal DNA (LSU rDNA) D1-D3 and D8-D10 regions, were G. yasumotoi and G. ruetzleri. The thecal plate morphology of the isolate, in particular the small pores and large 2’’’’ plate, most closely resembled G. yasumotoi. However, the ratios of the cell measurements (depth-to-width 1.3 and length-to-width 1.4) were more similar to G. ruetzleri and suggest that morphological variability exists within the globular Gambierdiscus group. The isolate produced putative maitotoxin-3, but no maitotoxin-1 or ciguatoxin.

Eat your orchid and have it too: a potentially new conservation formula for Chinese epiphytic medicinal orchids

About a quarter of Chinese wild orchid species are used in traditional medicine or as health food supplements. The market demand for some species, such as those in the epiphytic genus Dendrobium, has diminished many wild populations to local extinction or dangerously small numbers. Conservation of these heavily exploited orchids currently relies on a two-pronged approach: establishing nature reserves and encouraging massive commercial cultivation in artificial settings. We argue that these measures are not sufficient to restore or maintain healthy wild populations, and augmentation and reintroduction of these species in natural forests are needed. We argue for an unconventional reintroduction approach, in which populations planted in natural forests are allowed to be sustainably harvested (restoration-friendly cultivation). Because Dendrobium orchids are epiphytic, restoration-friendly cultivation of these species will not be at the expenses of other native plants. In addition, market premiums on wild-collected medicinal plants will generate incentives for farmers who participate in restoration-friendly cultivation to preserve natural forests. With proper policy and oversight, the restoration-friendly cultivation of medicinal Dendrobium orchids will facilitate the conservation of these threatened species, encourage protection of natural forests, and benefit marginalized rural communities. Adding this restoration-friendly cultivation into the current mix of conservation approaches has the potential to turn deeply-entrenched traditional uses of orchids from a conservation challenge to a conservation success.

Wax plants (Hoya, Apocynaceae) evolution: Epiphytism drives successful radiation

AbstractHoya, a species‐rich, mostly epiphytic genus within tribe Marsdenieae (Apocynaceae), occurs in tropical and subtropical forests of the Indo‐Australian Archipelago (IAA). Previous molecular phylogenetic studies based on a restricted taxon sample have provided a first phylogenetic framework for the genus. Questions remain, however, about the evolution and relationships among the over 300 species of the genus. Here, we (1) present the first well‐resolved phylogenetic tree based on sequences of the plastid spacer regions trnH‐psbA, trnT‐trnL, and of the nuclear‐encoded ITS and 5′‐ETS regions, for 154 species covering all proposed sections and (2) we discuss the evolution of epiphytism and its possible role in the successful radiation of Hoya in the tropical forests of the IAA in light of the new phylogenetic results. According to our results, species of Hoya group into six major lineages (Clades I–VI) with widespread geographic distribution. The earliest‐diverging epiphytic lineages of Clade I are restricted to subtropical continental Asia or tropical to subtropical Australasia (Clade IV), whereas their non‐epiphytic relatives are limited to the tropical Indomalayan (Clade II/III) and Australasian (Clade II) parts of the IAA. Clade V (tropical Indomalaya and Australasia) and Clade VI, with outposts in the Himalayas, Japan, and throughout Australasia, represent the second phase of diversification within Hoya. We hypothesise that Hoya is of tropical to subtropical Indo‐Burma/Himalayan origin and that the common trait epiphytism is connected with the onset of monsoon climates during the Himalayan uplift. The subsequent dispersal of Hoya into the many subareas of the IAA region and eventually Australia and the Southwest Pacific, and its success‐ ful radiation there, are proposed to be linked to its epiphytic life style, a trait that is today only found in 10% of angiosperms.

Floristics and environmental factors determining the geographic distribution of epiphytic bromeliads in the Brazilian Atlantic Rain Forest

We investigated how epiphytic species and subfamilies of Bromeliaceae change along the extent of the Atlantic Rain Forest, to answer the questions: (i) How do the epiphytic genera and subfamilies of Bromeliaceae change along the domain? (ii) How similar are the different regions of the Atlantic Rain Forest in relation to the epiphytic species of bromeliads? (iii) Which environmental variables are the most important factors in determining species composition along the domain? We found 114 species of Bromelioideae and 73 of Tillandsioideae. The predominance of Bromelioideae was unexpected, because they are not wind-dispersed as would be expected for most epiphytes. The smaller number of species of Tillandsioideae, and the high frequency of species of Vriesea with limited geographic distributions indicated that epiphytes with rather limited geographic distributions predominate in this domain. Species similarity was divided into one block of south–southeastern localities, and a second block of northeastern–southeastern localities. These results suggest that the distribution of epiphytic bromeliad species resembles that of the phorophyte trees, more than a previous pattern suggested for all epiphytes in the domain. Latitude, temperature and altitude were important factors affecting the species composition along the domain. In general, our results differ from those of other studies in Latin America, and we suggest that historical and evolutionary events generated these differences.

Tramps, narrow endemics and morphologically cryptic species in the epiphyllous liverwort Diplasiolejeunea

Diplasiolejeunea is a pantropical, epiphytic genus of leafy liverworts that occurs from the lowlands to more than 4000m altitude. Phylogenetic analyses of a molecular dataset consisting of three markers (nuclear ribosomal ITS region, plastidic trnL-F region and rbcL gene) and 122 accessions (plus two outgroups, Colura and Cololejeunea) indicate that the evolutionary diversity of Diplasiolejeunea is underestimated by current morphology-based classification. Four morphologically semi-cryptic species have been recovered. The molecular phylogenies support a deep split into a Neotropical and a Paleotropical clade, the latter structured into Australasian, Asian and Afromadacascan lineages. Presented results confirm the ranges of two pantropical species (D. cavifolia, D. rudolphiana), provide evidence for dispersal from the Neotropics into the Paleotropics, indicate speciation along altitudinal gradients and demonstrate extensive morphological homoplasy. We propose a revised supraspecific classification of Diplasiolejeunea into a predominantly Paleotropical subgenus Physolejeunea and predominantly Neotropical subgenera Austrolejeuneopsis and Diplasiolejeunea, the former containing mainly epiphytic species, the latter mainly epiphylls. Several clades are supported by combinations of morphological character states, and could be assigned to sections at some later point. This is the first comprehensive phylogeny of a largely epiphyllous genus of liverworts.

The Orchids of Tonga, Niue, and the Cook Islands

Orchids are one of the largest families of flowering plants in the Pacific region, especially in the tropics. Despite the remoteness of Tonga, Niue, and the Cook Islands, orchids have reached them in some numbers. Both terrestrial and epiphytic genera are well represented in the floras of these distant but neighboring archipelagos. Most of the species are found elsewhere in the Pacific, particularly in Fiji, Samoa, and the Society Islands. The affinities of these orchids can be traced to New Guinea and the adjacent archipelagos. New Guinea, with an estimated 3000 species that make it one of the richest orchid floras in the world, is a fertile source of seed for the scattered islands that lie to its east and southeast. The orchids appear to have reached Tonga, Niue, and the Cook Islands in recent times. Only two species, Habenaria amplifolia from Rarotonga and Robiquetia tongaensis from Tonga, are endemic to the islands covered in the present book, and both are closely related to more widespread Pacific species. This guide constitutes the fourth of a series of orchid floristic treatments that have so far covered Vanuatu (Lewis & Cribb 1989), the Solomon Islands and Bougainville (Lewis & Cribb 1991), and Samoa (Cribb & Whistler 1996). A recent, excellent and detailed account of the Fijian orchid flora (Kores 1991) has also been a valuable source for those interested in Pacific islands orchids. These accounts have generated renewed interest in the orchid floras of those archipelagos, leading to new discoveries and re-interpretations of several species. We hope that this small guide will likewise bring a renewal of interest in not only the orchids, but also the floras of these islands as a whole.

EFFECTS OF EMERGING SHOOT SIZE, TEMPERATURE, AND BENZYLADENINE ON GROWTH AND FLOWERING OF ZYGOPETALUM REDVALE 'FIRE KISS'

Zygopetalum is an epiphytic and terrestrial orchid genus that originates from mountainous regions of South America and has exotic, fragrant flowers. We performed experiments to determine how emerging shoot length, temperature, and application of benzyladenine (BA) influence growth and flowering of Zygopetalum Redvale 'Fire Kiss'. In the first experiment, the length of one immature vegetative shoot was measured on each 4-year-old plant at week 0 and plants were assigned to groups based on emerging shoot length: 1.0 to 2.0 cm, 3.0 to 4.0 cm, 6.0 to 7.0 cm, or 9.0 to 10.0 cm. Plants were transferred to environmental chambers with constant temperatures of 12.5, 15.0, 20.0, or 25.0°C and a 9-h photoperiod and grown for 8 weeks. Plants were then grown in a greenhouse at a constant temperature of 23°C with a 16-h photoperiod. After 73 days, 63 or 75% of plants had developed a visible inflorescence (VI) if emerging shoots between 3.0 and 7.0 cm in length were exposed to 12.5 or 15.0°C. No plants developed a VI when grown at 20 or 25°C, regardless of shoot length. In the second experiment, vegetative 5.5-year-old plants were grown in a greenhouse with a constant temperature of 14 or 20°C and a 16-h photoperiod. Plants received a foliar spray application (volume of 0.2 L·m -2 ) of BA at 200 or 400 mg/L at weeks 0 and 4 or weeks 4 and 8. Control plants did not receive a BA application. At week 8, plants were transferred to a greenhouse at a constant temperature of 20°C with a 16-h photoperiod. After 4 weeks, plants that were treated with BA had developed a mean of 7.2 to 10.7 new immature shoots per plant, while untreated plants had only 0.4 to 0.8 new shoots. Thus, application of BA could be used to stimulate shoot development to increase vegetative growth of Zygopetalum.

Temperature and Pseudobulb Size Influence Flowering of Odontioda Orchids

Odontioda is a cool-growing, sympodial epiphytic genus of orchids originating from the Andes Mountains of South America. Several hybrids are commercially grown as potted flowering plants for their brightly colored flowers and compact growth habit. We quantified how constant and fluctuating day/night temperatures influenced inflorescence initiation, time from visible inflorescence (VI) to flower, and pseudobulb development. Odontioda George McMahon ‘Fortuna’ and Lovely Penguin ‘Emperor’ were grown at constant temperature set points of 14, 17, 20, 23, 26, or 29 °C and day/night (12 h/12 h) temperatures of 20/14, 23/17, 26/14, 26/20, 29/23, or 29/17 °C. Plants were grown in glass greenhouses under a 12-h photoperiod and a maximum irradiance of 500 μmol·m−2·s−1. Within 6 weeks, heat stress symptoms such as leaf necrosis were observed on plants grown at a day temperature of 26 °C or greater regardless of the night temperature. After 20 weeks, 90% or greater of both clones had a VI when grown at a constant temperature of 14 or 17 °C. Plants grown at a constant temperature of 17 °C had the greatest pseudobulb diameter with a mean increase of 3.5 to 4.0 cm. In all treatments, a minimum pseudobulb diameter was required for uniform inflorescence initiation; pseudobulbs with a diameter of 5.5 cm or greater developed a VI in 93% of plants. Data for time from VI to open flower were converted to a rate, and a thermal-time model relating temperature with inflorescence development was developed. The base temperature and thermal time for VI to flower in George McMahon ‘Fortuna’ and Lovely Penguin ‘Emperor’ were estimated at −0.1 °C and 1429 °C·d−1 and 0.8 °C and 1250 °C·d−1, respectively. This information could be used by commercial orchid growers to assist in producing potted flowering Odontioda orchids for specific market dates.