Everything you need to know about cultivating and growing a rajnigandha plant. Learn about: 1. Cultivation Technology of Tuberose (Rajnigandha) 2. Soil and Climate Suitable for Growing Rajnigandha Plant 3. Propagation 4. Preparation of Land 5. Planting 6. Manures and Fertilizers 7. Interculture and Aftercare 8. Pests and Diseases 9. Harvesting and Yield 10. Uses of Rajnigandha Oil.
Cultivation Technology of Tuberose (Rajnigandha):
Tuberose is commonly called as Rajnigandha, cultivated for its white tube like fragrant flower, concrete and absolute. The tuberose belongs to the genus Polianthes and species tuberose, the name ‘tuberose’ is derived from tuberosa, this plant being the tuberous hyacinth. Tuberose was cherished and cultivated in Mexico before the Spain, it is one of the many flowers which have come to us from the ancient culture.
The two species i.e. Hyacinthus Indicus tuberosus flore, called ‘tuberose’ and Hyacinthus Indicus tuberosus flore pleno commonly called ‘the double tuberose’ found in the world. This plant was taken to Europe towards the end of 16th century. How and when the tuberose found its way to India and later to Sri Lanka and elsewhere in the orient is probably an un-documented history.
Soil and Climate Suitable for Growing Rajnigandha Plant:
Tuberose can be cultivated in various types of soils preferably pH range of 6.5 to 7.5, light sandy loam to a clay loam. At least 50 cm deep, well drained, friable soils rich in organic matter and nutrients with plenty of moisture are preferable. It can be grown successfully as a commercial crop under high saline-alkaline conditions with better agronomical practices, some scientists observed that increasing the levels of NaCI and very low concentration of CaCl2 affects vegetative growth and flowering of tuberose.
Rajnigandha can be grown with success under wide environmental conditions ranging from tropical to sub-tropical and temperature climate. If the climate is mild and free from extremes of high and low temperature, profuse flowering can be obtained almost throughout the whole year. Tuberose should be planted when the temperature is between 24° to 30°C; for plant growth 13 to 18°C is good, and the blooming is better from 10 to 13°C.
Commercial cultivation of Rajnigandha in India is mainly confined to warm humid areas with average temperature range from 20 to 35°C. High atmospheric humidity and temperature around 30°C is optimum. The Spike length and quality of flower is affected if the temperature is above 40°C; very low temperature and frost also damage the plants and flowers.
Propagation of Rajnigandha (Tuberose):
Rajnigandha is propagated by both methods from seeds, bulbs and bulblets. The seeds are difficult to germinate and hence, these are to be sown evenly at a depth of 1.0 to 1.75 cm in well prepared mixture containing leaf mould, garden soil and sand in equal proportions in nursery bed or seed pan. Under favourable soil temperature (26.6°C) and moisture, the seeds germinate within two to three weeks after sowing. When the seedlings are sufficiently grown, they are transferred to the final field. Multiplication of tuberose is done commercially by bulbs.
Tuberose bulbs planted once can be kept undisturbed for 2 to 3 years to come. If large sized bulbs are planted and proper care is taken the flower yield will be maximum in first two years, and thereafter the yield will reduce successively in the following years. Number of spike per plant varies from 1 to 3, which attain a length of 90 to 120 cm with 20 to 35 flowers. Tuberose bulbs are easily winter killed, so in temperate climate, they are usually dug and stored during the winter months. The small new bulbs require three years of cultivation before they are capable of producing bloom.
Preparation of Land for Planting Rajnigandha:
Before planting of Rajnigandha, first ploughing is done in the month of January so that, in the dry season with good sunshine, the uprooted ploughed weeds are completely destroyed. Second ploughing is done about a month before planting, and well-rotted farm yard manure or cow dung be incorporated during ploughing operation at the rate of 40-45 tonnes per hectare. Then the clods are to be loosened, soil is brought in good tilth and the weeds are thoroughly removed. Tuberose is a sun-loving plant and bloom luxuriantly on well drained soils possessing sufficient moisture holding capacity. They are very susceptible to poor drainage conditions.
Planting of Rajnigandha Bulbs:
Planting of fresh bulbs as such leads to profuse vegetative growth and less flowering. Before planting, it is better to store the bulbs for nearly two months in a well-ventilated warm (minimum temperature 12-14°C) dry place. If kept moist and cool, the bulbs are likely to rot at the centre. Healthy tubers will always be green at top or show some sign of life at the growing point. Before planting, bulbs should be treated with copper fungicide. In India, tuberose is generally planted in February-March in plains and in April-May in hills however, in south India, planting of bulbs during July-August is preferred.
To obtain flower almost throughout the year, sequential planting can be practiced. Planting of large size bulb (3.0 to 3.5 cm in diameter) significantly improves the yield and quality of flower spike. It is planted at 3-10 cm depth, depending upon size of bulb and texture of soil viz., deeper in light soils. Spacing varies with the soil and climatic conditions, 1,00,000 to 2,50,000 bulbs are required for planting in one hectare of land with the distance of 20 cm x 30 cm and 30 x 30 cm spacing is recommended according to soil condition.
Manures and Fertilizers Required for Growing Rajnigandha Plant:
The nutritional requirement of tuberose varies with the soil and climate, in normal soil, FYM at the rate of 25 to 45 tonnes per hectare help proper establishment of bulbs. Apart from the organic manure, Nitrogen, phosphorus and potassium markedly influence the growth and development of plants. The deficiency of nitrogen and phosphorus completely suppressed flowering in tuberose. The deficiency of calcium causes cracking of the flower spike and its acute deficiency results in bud rot.
Magnesium deficiency causes leaf bronzing, promoting yellowing on both sides of the midrib and poor growth. Sulphur is required to increase oil content in flowers, and its deficiency causes chlorosis of leaves. Iron, manganese, zinc, aluminium and copper are available at low pH ranges, whereas the availability of boron decreases below 4 and above 7.5 pH ranges.
In alkaline-saline soils, application of 35 kg nitrogen and 55 kg phosphorus per hectare has been found very beneficial and further analysis revealed that very high quantities of salts are removed by tuberose. However, in normal soil 100 kg Nitrogen, 50 kg phosphorous and 35 kg potash is required for good growth and yield of flowers.
Inter-Culture and Aftercare of Rajnigandha Plant:
Proper weeding, hoeing and irrigation of crop resulted for good growth arid yield. The earthling up enables the spikes to grow erect and hoeing in the plantation is routinely done to soil for attaining good growth. About 3-4 manual weeding is recommended to avoid growth of unwanted weeds. Regular irrigation is required for good growth and yield of the crop. First irrigation is applied just after planting of bulbs and rest is as and when required.
Pests and Diseases of Rajnigandha:
To avoid pest and disease free field regular watch of the crop is required. Tuberose is a hardy crop and are less affected by the attack of insects, pests and diseases. However, aphids and grasshopper feed on the flower buds and young leaves which can be controlled by 0.1 per cent spray of malathion or rogor at fortnightly interval. Red spider mites suck plant sap, and the leaves become yellow or bronze in colour.
Few other common pest are attached on the plant, Red spider mites suck plant sap, and it is control by spraying of Metasystox, wettable sulphur or kelthan. Thrips attack the flower which ultimately controlled by spraying of nuvacron or soil application of thime damage shoots. Tuberose is attacked by fungi masses on leaf surface or near the so loose green colour due to rotting which extend the plant become weak and bear fewer or no flowering. This is controlled by spraying of nuvacron or soil application of thimet.
Leaf spot is another disease caused by Alternaria polyantha in tuberose, spraying of 1 per cent Bordeaux mixture, 0.4 per cent zineb or 0.5 per cent ziram is recommended for controlling the disease. Tuberose is also attacked by rust and powdery mildew which are not serious. Spray of sulphur is recommended in such cases.
Harvesting and Yield of Rajnigandha:
Rajnigandha is largely cultivated for production of flower spikes and loose flowers. For marketing of flower spikes, the tuberose is harvested by cutting the spikes from the base when quite a good number of flowers open on the spike. Picking of individual flowers is completed by 4.0 AM to 8.0 A.M. It has shelf life of 2-5 days. The yield of fresh loose flowers per year per hectare for production of concrete in single tuberose varies from 12 to 15 tonnes. In the first two years, flower yield is high, and declines considerably in the third year is started.
For extraction of concrete and absolute, it requires solvent extraction process. The first extraction of fresh flower yields the floral concretes 0.2 and 0.12 per cent absolute. The absolute is a highly viscous or semi-liquid brownish mass with powerful and lasting odour, truly reminiscent and characteristic of fresh flowers. It may be mentioned here that steam or hydro- distillation of tuberose flowers can be carried out but produces only a very less yield of essential oil and very poor odour.
The total yield of concrete from one ha. of land is 7 to 10 kg. Concrete of tuberose is a light to dark brown, waxy, quite hard mass, only partly soluble in high grade alcohol. Tuberose isolates contain methyl benzoate, methyl anthranilate, benzyl alcohol, benzyl benzoate, butyric acid, probably phenyl acetic acid, methyl salicylate, eugenol, geraniol, nerol both free and as acetates and farnesol.
Uses of Rajnigandha Oil:
The odor is intense, heavy sweet floral, honey with orange, green, oily-fatty undertone. Oil is produced rarely, normally absolute (by solvent extraction and further extraction by alcohol) is manufactured at industrial scale and is used.
It is used in fine fragrances for men and women both. The use level is 0.1 to 1.0%, very rarely perfumers use more than 1% in any formulation being costly material. Normally for sweet, heavy floral fragrances it is used.
It is allowed to be used in flavours but used only in traces.
The tuberose absolute is used in high quantity when cost allows to be used in high class floral fragrances of heavy and sweet type such as frangipani, lilac, heliotrope, gardenia, violet and heavy oriental types, oppoponax, in fantasy perfumes, etc.
The tuberose does not have much use in Aromatherapy.