Common name: Orchid
Botanical name: Many genus and species like Vanilla planifolia, Dendrobium nobile etc.
Nepali name: Sungava, Sunakhari
Orchids are the loveliest and wondrous among all the flowering plants in the world. The exquisite beauty of flowers, brilliance of colors, remarkable range of sizes, manifold shapes, variation in the form, attractive habits and wide distribution in the earth have aroused the highest admiration for those charming plants throughout the world. These extraordinary plants belong to the very large and diverse family Orchidaceae. The orchids with their 35000 species and over 800 genera, constitute the largest family among the flowering plants and are the only major cut flower crop commercially grown and as a pot plant. In Nepal 350-500 species of orchids are found distributed in different eco-zones.
- Orchids are the most fascinating and beautiful of all flowers so they are used in indoor decoration and gardens.
- It is a multimillion-dollar business in the world.
- Orchid like Dendrobium nobile has some medicinal value as an antipyretic and tonic.
- Leaves of some orchid like Aoectochillus are used as vegetables.
- Dried and cured leaves and pseudo bulbs are sometimes used to prepare beverage and tea.
- Stem of Dendrobium spp. are used for weaving baskets.
- Based on growth habits
- Monopodial orchids
- One single main stem and continuous to grow indefinitely.
- Results in the pyramidal forms of the growth of the growth typical of conifers, e.g. Vanda, Rhynchostylis spp., Phalaenopsis etc.
- This is also known as one footed orchid.
- Sympodial orchids
- In this, the growth in which the apical bud withers at the end of growing season.
- Growth is continuing by the lateral bud in the following season.
- Bear pseudo bulbs and grow sideways.
- Known as many footed orchids.
e.g. Dendrobium spp., Cymbidium spp., Cattleya, Vanilla etc.
- Based on Habitat
They grow on the branches and stem of the trees and produce epiphytic roots. They absorb nutrients from the branches and stem of the tree but do not suck the sap of the plant, e.g. Vanda, Arides, Cymbidium etc.
Grow and survive on dead organic matter or body of the plant, e.g. Epipogon
Grow on rocks, e.g. Lipapis spp.
Grow on ground, e.g. Cattleya spp.
Climatic and environmental requirements
Cool orchids (10-13C): Cymbidium, Paphiopedilum
Intermediate orchids (13-18C): Cattleya, Laelia, Miltonia, Oncidium
Warm orchids (15.5-26.5C): Vanda, Rhynchostylis, Phalaenopsis, Dendrobium
Almost all orchids require 2400 foot candle except 2400 foot candle except Paphiopedilum do best in low light intensity i.e.800-1200 foot candle.
Eight hours light induced early flowering which additional light delay flowering but enhance vegetative growth. Flower initiation and development in cattleyas takes place under short days.
High RH (i.e.80%) is generally preferred by most of the orchids at daytime. Cymbidiums prefer RH between 40-70% in the greenhouse. Flower buds of Cattleya are more susceptible to infection at higher RH.
Free circulation of fresh air in the green house is necessary to maintain the uniformity of temperature.
Multiplication of orchids
Dividing large clumps to smaller clumps after they have reached a good size (10-12 number) e.g. Cattleya, Laelia, Cymbidium, Dendrobium etc.
Division is done when flowering is over during April-May.
Seed germination in orchids may be symbiotic or non-symbiotic. In the symbiotic process seeds require fungal association for their germination while non-symbiotic method involves the germination of seeds in an agar medium supplemented with various nutrients.
Similarly, orchids can be propagated by cutting and layering and meristem and shoot culture.
Under controlled condition, orchids can be grown in specially designed orchidarium or orchid houses, running north to south. Orchid houses can be made of materials like split bamboos, glass, shade, nets etc. For maintaining humidity, tank filled with water is placed in the house at the center, or artificial fogging nozzles are made.
Plastic pot is preferred over mud pots as they render moisture for a longer interval. Monopodial orchids perform well in media containing chunks of hardwood charcoal while sympodial orchids in tree fern fiber media.
Manures and fertilizers
During vegetative growth, large amount of nitrogen is required while during flowering nitrogen content should be reduced and phosphate must be increased. Fertilization should be carried out only when the plant is actively producing new leaves. During active growing season, it needs heavy feeding regularly with 20:20:20 NPK at rate of 56 g per 380 liters of water. Fertilizer should be applied bimonthly.
The initial spikes are very small and are pinched off to improve the quality of next upcoming spike. The dead spikes are cut from the bottom. Stalks that turn yellow are completely removed from the main stem. Pruning helps the plant produce more flowers during the next season.
In general, orchid flower do not mature until 3-4 days after they open. Flower harvested before maturity may wilt soon. So, they must be harvested when the flowers are fully matured and their tissues are hardened.
After harvesting spikes, they should be immediately dipped into water and stored at temperature of 5-70C. The flowers should be packed in airtight, waterproof, strong boxes. Wet cotton must be kept in the cut of flower stem wrapping with polythene wrapper. Foliar application of aluminum chloride at 500ppm,ammonium molybdate at 100ppm or boric acid at 1000ppm lengthened the vase life.