DENDROBIUM IS the largest genus of the Orchidaceae family containing more than 1,800 species that are found in diverse habitats throughout much of South, East and SouthEast Asia, including China, Japan, India, Philippines, Indonesia, Australia, New Guinea, Vietnam, and many of the islands of the Pacific. In Bangladesh, 27 species of Dendrobium are distributed throughout the country especially Chittagong, Chittagong Hill Tracts, Cox’s Bazar, greater Sylhet, Gazipur, and Sundarbans forest (Huda, 2007). Dendrobium is the leading genus for phytochemicals content and 100 compounds including 32 alkaloids, 22 phenanthrenes, 15 bibenzyls, 7 sesquiterpenoids, 6 coumarins, and 4 fluorenones have been identified in 42 Dendrobium species (Hossain, 2015). Dendrobium formosum Roxb. ex Lindl. is an epiphytic pseudobulbous orchid found on trunks of large trees; it flowers in the month of May. The large attractive flowers of the species have horticultural importance. The biological status of this species is Vulnerable (VU) due to habitat destruction and mass collection by orchid hunters (Huda, 2008). In Bangladesh, the species was recorded from Sylhet, Chittagong, and Cox’s Bazar district. The present study was therefore, designed to evaluate the in vitro asymbiotic germination potential of its seeds, growth and multiplication of protocorms, differentiation of first leaf and root primordia, and development of seedlings, with a view to developing mass propagation protocol for this species.
ORCHIDS CONSTITUTE the most diverse family of flowering plants with 28,484 species (Govaerts et al., 2017) representing ca. 8% of all vascular plants worldwide (Dressler, 2005; Scotland and Wortley, 2003). The drivers behind this diversification appear to be linked to several factors especially co-evolution with specific insect pollinators needed for sexual reproduction. The majority (60-70%) of orchid species entice and reward pollinators within a blend of attractants that typically include oils, waxes, fragrance (aromatic compounds) and sugar-rich nectar (Ackerman, 1986; Brzosko and Mirski, 2021; Dressler, 1981; Tremblay et al., 2005). About 35 million years ago, orchid speciation accelerated when the family adapted to an arboreal lifestyle aided by their ability to conserve water via crassulacean acid metabolism or CAM (Stokstad, 2015), and flowers targeted winged insects especially bees (Hymenoptera) and moths (Lepidoptera) for pollination. This timeframe coincides with the evolutionary appearance of nocturnal hawk moths (Sphingidae; Kawahara et al., 2019) that pollinate many members of the Epidendroideae, the largest orchid subfamily. This subfamily includes the well-known angraecoids of Africa and Madagascar (Angraecum sesquipedale Thouars; Pridgeon et al., 1999, 2014), and members of the genus Dendrophylax in the New World. Collectively, moth-pollinated orchids are characterized by their white flowers that emit a sweetsmelling evening fragrance, and long nectar spurs that often match the proboscis length of the pollinator (Dressler, 1981; Faegri and van der Pijl, 1979; Pal et al., 2019; Prakash and Pathak, 2020). These spurs are often filled with copious amount of sugar-rich nectar that serves to reward the pollinator with a carbohydrate source needed to power muscles for rapid flight over long distances.
THE FAMILY Orchidaceae is one of the most advanced and largest families of angiosperms comprising of about 28,484 species (Govaerts et al., 2017), and has always been interesting to evolutionary biologists because of its remarkable floral forms and diversity in pollination systems (Darwin, 1877). In India, the Eastern Himalayas (including the NorthEast India), the Western Ghats, and the Western Himalayas are the three major centers of orchid diversity, with a total strength of about 1,256 species of orchids in 155 genera (Singh et al., 2019). The great geographic expanse of the country encompassing a variety of bioclimatic zones and the enormous diversity of ecosystems account for the bewildering array of orchid species in India. The tremendous floral diversity and evolutionary radiation of orchid species is often linked to their intimate pollinator relationships with 60-70% of orchid species being dependent on discrete pollinator lineages or even single species (Cozzolino and Widmer, 2005). The highly specialized reproductive organs and exquisite structure adapted to insect pollination are amazing. The mutual beneficial relationship between plants and pollinators is common in ecosystems (Pal et al., 2019). However, a considerable number of angiosperm species do not provide rewards for pollinators, and have instead developed deception mechanisms to allure insects to visit their flowers and these insects complete pollination process without receiving anything, in return. This is known as deceptive pollination (Goodrich and Jurgens, 2018). No-reward pollination mechanisms have been recorded in at least 32 angiosperm families, including 7,500 species, of which 6,500 belong to Orchidaceae (Jersakova et al., 2006). Such a large number of deceptive pollination species being concentrated in one family has attracted much attention from a diverse range of researchers in plant systematics, pollination biology, and evolutionary biology (Renner, 2006; Schiestl, 2015). Nearly one-third of Orchidaceae plants rely on deceptive pollination, which might be one of the important reasons for the diversity of orchids (Stokstad, 2015). The orchids use or manipulate insect behavior, including foraging, mating, oviposition, and inhabiting, and have evolved various deceptive pollination mechanisms. Common types include generalized food deception, batesian mimicry, sexual deception, oviposition mimicry, and habitat mimicry, of which the first three are the most common (Cozzolino and Widmer, 2005; Scopece et al., 2010, 2017). Generalized food deception refers to the fact that orchids provide false food signals to insects, such as false pollen or spur without nectar, to trick insects to forage on flowers, and complete the process of pollination. If the orchid mimics a particular rewarding and synchronized flowering plant, this deception is termed batesian mimicry.
CROP DISEASES are outcome of interaction of crops and pathogens favoured by environment and are visualized as symptoms or signs in the crops. Orchids comprised fascinating and attractive floriculture crop known for its flowers with unique shapes, colours, forms, fragrances, and long shelf life. Commercially, orchids are cultivated as potted plants for aesthetic purpose and cut flowers for market demand (NRCO, 2015). India is native to 1256 orchid species comprising of 155 genera (Singh et al., 2019). The Himalayas, the NorthEast region, and Western Ghats are the hot spot regions for orchid distribution. Arunachal Pradesh leads in orchid diversity with 612 orchid species followed by Sikkim with 560 species and Darjeeling hills of West Bengal with 479 species (Singh et al., 2019). Orchids are cultivated in controlled polyhouses for commercial purpose under which favourable environment for bringing out the crop is maintained. These favourable parameters also assist in the development of insect pests and diseases which bring about quantitative and qualitative loss to crops. Knowledge of diseases is pre-requisite to bring effective management. Some new diseases are on reports, minor diseases are becoming major with more threat to yield and host range of pathogens is getting widened. Eukaryotic fungi, prokaryotic bacteria, and living intermediate viruses cause many diseases in orchids thereby bringing down their yield potential. With a view to compiling orchid diseases reported so far, the present communication reports the review on current status of orchid pathogens in India.
ORCHIDS WITH over 28,484 species in approximately 850 genera represent one of the most advanced and largest families of angiosperms with innumerable hybrids and varieties (Govaerts et al., 2017). These orchids are distributed around the globe except for the freezing Antarctic region and deadly hot desert areas. They have extremely high floricultural appeal because of the extraordinary beauty of highly enchanting flowers with their an incredible range of variations in floral shape, size, colouration, and fragrance. Atharva Ved was the first to present documentary evidence for medicinal uses of orchids followed by Charak Samhita, Sushrut Samhita, and Kashyap Samhita. A copy of Charak Samhita was sent to Bagdad for the princess of Barmecides tribe, from where it went to China (Kaushik, 1983, 1985, 2019). These are also used as source of food, glues, gums, narcotics, essences, and perfumes (Chinsamy et al., 2014; Lawler, 1984). Heptacosane and Octacosanol isolated from Vanda roxburghii roots were found to have anti-inflammatory activity (Chawla et al., 1992). Various phytochemicals with high biological activity including carotenoids, flavonoids, phenolics, and their derivatives were found in orchid extracts that showed powerful antioxidant activities (Hoque et al., 2021; Joseph et al., 2018; Sanjana et al., 2021; Sharma and Pathak, 2020; Stajner et al., 2010). The antioxidant activities of these compounds are based on scavenging diverse reactive oxygen species (ROS) including peroxyl radicals, hydroxyl radicals, hypochlorous acid, superoxide anions and peroxynitrite, thus protecting the human body against oxidative damages (Chao et al., 2014). Dendrobium crepidatum Lindl. & Paxt. is an epiphytic orchid, confined to an altitude range of 600-1400 m. This species has medicinal as well as ornamental value (Chen and Ji, 1998); it is widely used in traditional Chinese medicine for the treatment of cancer, diabetes, cataracts, and fever (Lam et al., 2015). The present study was carried out so as to determine antioxidant and anti-inflammatory potential in both in vivo grown plants and in vitro raised plantlets of D. crepidatum.
Android applications are expanding their utility in agriculture to simplify the process and procedures and to disseminate the knowledge amongst farmers and researchers. Orchid-Mobile Assisted Notebook (MAN) application has been developed and hosted on Google Play Store to simplify passport data entry for orchid explorers. The application was developed for android users and supports android version 4.1 (API 16) to 10.0 (API 30) smartphones using offline inbuilt SQLite DB, Core Java program coded in Android Studio Platform. The app provides a digital notebook platform to store a large number of data with photographs in a systematic manner. Users can easily transfer their data in MS Excel format anytime or anywhere. App is offline and stand alone to protect data at user’s end. More information and feedback features help users to know additional details and direct their query to the developer- ICAR-NRC for Orchids. This app assists as digital field book for orchid collectors, growers, researchers to maintain records of orchid germplasm collected, cultivated, and maintained at their level.
Orchid farming is one of the horticultural enterprises in accelerating the growth of economy as it offers not only a wide range of options to the farmers for crop diversification but also provides ample scope for sustaining orchid industry which may generate huge employment opportunities. Orchid research and development has been given focussed attention in Andhra Pradesh with congenial climatic conditions for tropical orchids especially in the coastal districts. As a result of certain policy and technological initiatives with logistic support, orchid cultivation, in Andhra Pradesh is gaining momentum as sustainable and viable venture for the farmers; besides this sector has also started attracting entrepreneurs for taking up orchid cultivation as a commercial venture. A progressive farmer from East Godavari district, Andhra Pradesh who started orchid farming in 2000 sqm land (with 25,000 plants) with the support of the Department of Horticulture in May 2019, has started getting high returns indicating thereby that orchid cultivation may prove as a good opportunity for other farmers as well in the state to take up orchid cultivation. Therefore, there is a great scope for the orchid industry to grow and flourish, in the country.
Splendid slipper orchid Paphiopedilum insigne (Wall. ex Lindl.) Pfitzer is a species of ornamental significance both in domestic and international trade. The present study was undertaken to characterize Paphiopedilum insigne specimens for various morphological and floral characters and to investigate genetic variability and relationships amongst P. insigne specimens and the type species for the purposes of further breeding.
Thailand is the origin of about 1,300 tropical orchid species in 178 genera. Deforestation and over-collection of wild Thai orchids for trade has placed these species at a risk of extinction. Therefore, the conservation, as well as sustainable use is urgently needed to conserve these by various means. The genus Paphiopedilum and Dendrobium cruentum are listed in Appendix I of CITES. Presently, various methods of cryopreservation of Thai orchid species were implemented. For cryopreservation, recent methods were used, namely vitrification (dehydration in PVS2 solution, consisted of 30% (w/v) glycerol, 15% (w/v) ethylene glycol, and 15% (w/v) dimethyl sulfoxide, prepared in modified Vacin and Went liquid medium), encapsulation-dehydration (encapsulation in calcium alginate beads followed by airdrying in a laminar air-flow cabinet), encapsulation-vitrification (encapsulation in calcium alginate beads followed by dehydration in PVS2 solution), droplet-vitrification (fast freezing from small drops of PVS2 solution on aluminium strip), and cryo-plate (a combination of encapsulation and droplet on very fast freezing aluminium plate) dehydrated with silica gel and drying beads. Application of these methods in seeds was successful in Dendrobium chrysotoxum (99% vitrification), D. cruentum (32% vitrification; 58% D cryo-plate), D. draconis (95% vitrification), D. hercoglossum (80% encapsulation-vitrification), Doritis pulcherrima (62% vitrification), Paphiopedilum exul (30% encapsulation-vitrification; 14% encapsulation-dehydration), Rhynchostylis coelestis (85% vitrification), Vanda coerulea (67% vitrification) as well as in protocorms of Acampe rigida (17% V cryo-plate; 74% D cryo-plate), Arundina graminifolia (76% and 74% cryo-plate dehydrated with drying beads and silica gel, respectively; 33% droplet-vitrification; 64% encapsulation-dehydration with drying beads or silica gel), Dendrobium cariniferum (15%, encapsulation-vitrification), D. cruentum (33% vitrification; 27% encapsulation-dehydration), Grammaytophyllum speciosum (14% encapsulation-vitrification), Rhynchostylis gigantea (19% vitrification), Seidenfadenia mitrata (67% vitrification), Vanda coerulea (40% encapsulation-dehydration), and in pollinia of Dendrobium signatum (56% and 50% V cryo-plate and D cryo-plate, respectively). Cryopreserved seeds, protocorms, and pollinia were able to develop into normal seedlings/plantlets. These methods appear to be promising techniques for cryopreservation of some Thai orchid species.
Indian economy is principally influenced by agriculture and allied activities. Orchids are known for their high ornamental value due to their magnificent and graceful flowers. Apart from their use as decorative materials and cut-flowers, they are being used for various purposes such as herbal medicines, source of phytochemicals and in aromatic products due to their pleasant fragrance. Potential medicinal value and possible orchid flower export for the subcontinent are not yet adequately explored and estimated. The state of Andhra Pradesh has good number of orchid taxa in all regions mostly in East Godavari and Visakhapatnam districts as an indicative of the extremes of moisture levels in the environment. A humid and warm atmosphere is congenial for the growth of most of the tropical orchids. Greenhouse is the most functional methodology for achieving the objectives of protected cultivation of orchids. Protected cultivation technique facilitates the production of orchids by providing complete controlled conditions. Some districts of Andhra Pradesh are suitable for the orchid production. The global demand for orchids creates possibilities for local cultivation of orchids apart from regular and sustainable harvest from wild stands
Understanding of genetic diversity is very important for the management of conservation in any endangered species. Vanda thwaitesii Hook.f. and V. wightii Rchb.f. are two notified endangered orchids of Western Ghats, India demanding evaluation of genetic diversity for conservation action and thus presently, these studies have been carried out. ISSR profile of 20 samples from 15 populations of Vanda thwaitesii in a spatial separation of 10-286 km from type locality exhibited very low heterozygosity (h=0.083) and reduced gene flow (Nm=0.01). The populations clustered into 3-4 groups without any correlation between geographic locations of plant distribution. Twenty eight samples of V. wightii from 15 distinct populations separated by 40-264 km from type locality revealed moderate diversity (h=0.25; Nm=0.98) but not having correlation with respect to geographical separation. Occurrence of majority of populations in highly fragmented habitats, low levels of genetic diversity and reduced/negligible gene flow shows the immediate requirement of conserving V. thwaitesii. In spite of the existence of moderate diversity, distribution of diversity amongst the populations in disturbed forests and inhabited land necessitate the rehabilitation/reinforcement of V. wightii into protected forests.
The paper includes all the monopodial orchid species i.e. 250 species (including 3 varieties) belonging to 43 genera, which have so far been recorded from India; these are tabulated with zonal-wise distribution. Amongst them, Luisia is the largest genus with 24 species followed by Thrixspermum (22), Vanda (21), Gastrochilus (20), Cleisostoma (18), and Phalaenopsis (17). Out of 250 monopodial species, 134 new species have been described from India. Out of them, 92 species are considered valid and 42 are reduced to synonyms. Further, amongst the 92 valid species, 38 are transferred to other genera, as new combinations. There are as many as 10 genera which are represented by only one species, in the country.
During the present study, the keikis were found on leaf apex of Eulophia graminea Lindl., a terrestrial orchid species found in Odisha. The
species though a threatened species at many places, has been designated as Early Detection and Rapid Response (EDRR) species by
the Florida Keys Invasive Species Exotics Task Force due to its invasive nature. The species has medicinal importance and is being used
for curing several chronic diseases since long, in India. Hence, the presently reported unique propagation method of the species may be
a blessing or a matter of serious concern amongst the scientists.
Being a part of biodiversity hotspots, the NorthEast India is home to various orchid species. The present study aims to conserve the populations of endangered orchid species of Manipur, using modern biotechnological techniques for the propagation of the species in a time efficient manner, both qualitatively and quantitatively. Literature survey on orchids of Manipur updated a total of 474 species, in the state. During field survey at different sites of the Manipur, we collected and conserved 81 orchid species including four slipper orchids [Paphiopedilum fairrieanum (Lindl.), P. hirsutissimum (Lindl. ex Hook.f.), P. insigne (Lindl.) Pfitz., and P. spicerianum (Rchb.f) Pfitz.]. Attempts were made to mass multiply some selected orchids using in vitro asymbiotic seed germination technique; seedling were obtained in Dendrobium transparens and Vanda coerulea. Furthermore, to encourage socio-economic upliftment of farmers through entrepreneurship programme, proposals have been put forth through interaction/outreach programmes.
Luisia trichorrhiza (W. J. Hook.) Bl., was observed to exhibit intraspecific colour variations in its natural populations of West Bengal.
Variations were observed in floral part such as sepals, petals, and lip. The normal floral colour was yellowish green with purple lip. The plant
that showed variations was observed with flowers having purple blotch on pale yellow lip. All other floral parts were more or less equal in
size but pedicellate ovary was larger in size. The local availability status of this species is common and the status of variant species is rare.
Its natural populations in the nature have drastically reduced as compared to earlier times when these plants were abundantly available
in Terai and Dooars (foot hills of Himalayas) region of West Bengal. The factors including urbanization, construction of roads and dams etc.
seem to be the major cause of habitat destruction of the species, in the region. Hence, conservation strategies need to be developed so
as to save the species, in its natural habitats.
The population of the medicinal plant, Habenaria longicorniculata J.Graham is shrinking due to habitat degradation and its over-exploitation Predicting potential geographic distribution of the species is important for conservation of a species and restoration of its habitat. The present study was carried out to predict the current and future suitable distribution of H. longicorniculata in India using Maxent species distribution model; 20,928 km2 of the total predicted area was found to be most suitable. Precipitation of the wettest month (Bio 13), precipitation of driest month (Bio 14) and isothermality (Bio 3) were the strongest predictors for the distribution of H. longicorniculata with 68% and 6.9% respectively. The model results suggest significant probable decrease of highly suitable habitat of 17% area, in future Therefore, proper conservation planning is needed for H. longicorniculata. The Maxent model used in this study can be used to forecast the distribution of the species and may be helpful for its rehabilitation and improving conservation status.