Potential of Tuberose Cultivation

By Dr. Ali Muhamamd Khushk

Tuberose is native to Mexico belongs to family Amaryllis, and commonly known as the lily has long been cherished for the aromatic oils extracted from its fragrant white flowers. It is a popular cut flower, not only for use in arrangements, but also for the individual florets that can provide fragrance to bouquets and boutonnieres. It has a high reputation in perfumery. The unique scent is wonderful, romantic and captivating. Among the flowers it occupies a very selective position because of its beauty, elegance and sweet pleasant fragrance. It is one of those plants, the flower of which continues to develop their natural perfume for some time after they have been harvested. The Flowers of this plant blossom in the night and passerby is engulfed by its sweet smell. Besides, oil extraction the flowers are also used to make the garland which is used during the marriage ceremony. The flower has been used for centuries in India to adorn the woman. Bouquets made from this flower may be presented by people when they visit each other.

It has gained considerable importance in growers of tropical regions of south East Asia. It is now-a-days, being commercially grown in big areas. It has great economic potential in the cut flower market and in essential oil industry. It grows in elongated spikes that produce clusters of aromatic white flowers that are 5-6 cm long and have a characteristic bending. Normal tuberose will grow to be about one foot in diameter. The flower spikes will be up to two feet in height. Tuberose flowers bloom from the bottom toward the top of the spike. The flowers remain fresh for a pretty long time and are suitable for long distance transportation.

Climate

Tuberose is tropical to semi-tropical plant. Basically, it needs warmth, sunshine, high relative humidity, well-drained soil, and even moisture. Shades of trees reduce flower production. The commercial cultivation of tuberose is mainly confined to warm, humid areas with average temperature ranges from 18˚to 32˚C.The ideal temperature for growth of plants ranges from 26˚to30˚C to accumulate photosynthesis for profuse flowering. The tuberose needs a long growing period in order to blossom in early to late fall. The spike production, along with the quality of flowers declines to a great extent during December –January except in “double varieties” of tuberose.

Soil

Tuberose can be successfully grown in a wide range of soils, even in soils affected by acidity or alkalinity to some extent. Tuberose is very sensitive to water logging even for a short period; it damages the root system and affects the plant growth and flowering. Loam and sand loam soil having pH range from 6.5 to 7.5 with proper aeration and drainage are considered best for tuberose cultivation. The soil should be rich in organic matter and retain sufficient moisture for proper growth. The soil should be thoroughly prepared for achieving desired results. Deep ploughing is necessary for bringing to a good tilth and for the eradication of weeds. About 12-15 tones of FYM/ha should be incorporated into soil three weeks before planting.

Planting Time

Tuberose can be commercially grown through out the year but highest yield is obtained from February to October. However, best time of planting is from second to last week of March, where as April-May is the appropriate time for Hilly areas.

Propagation

Propagation can be done by means of seeds and bulbs. Vegetative propagation is commonly practiced and desirable too, because such plants produce better flowers within a short period after planting. Vegetative propagation is done by means of bulbs. The bulbs of 2-3 cm wide are considered suitable for propagation. Planting of fresh bulbs produce less number of flowers hence, bulbs should always be kept in store for a month or more to ensure better production of flowers. Larger bulbs result in early flowering and higher yields. Bulbs are cut vertically in to 2-3 sections in such a away that each segment contains a bud for germination. The bulbs should be planted 4-5 cm deep in beds. Planting depth of bulb can also influence the growth and production of early flower and yield as well. It may vary from 4-7 cm depending on the size of the bulb and soil type .However, 4-5 cm depth is ideal for the bulb planting. Deep planting of bulb delays germination and flowers. The soil moisture should be maintained after planting of bulbs before monsoon starts. Plant population affects the yield and quality of flowers. The higher plant density produces greater yields of spikes, flowers and bulbs. Planting of bulbs at distance of 15cmx 20cm with a population of 3, 33,000 plants per hectare gives the highest yield of spikes, flowers and bulbs over a period of two years. Tuberose crop can stand well for three years in the same field. However, replanting after 3 years is a necessary practice; otherwise it invites pests and diseases with reduction in crop yield and quality.

In any case and no matter what the climate, tuberose are enchanting when grown in large pots (three roots to a 10" or 12" pot) that provide ample room for the vigorous root systems and allow for sufficient expansion of the tubers. Since plants grown in pots tend to be warmer than those grown in the ground, they often bloom a few weeks earlier as well. When grown correctly, the tubers multiply at an astonishingly fast rate and provide blooms from year to year.

Varieties

The main varieties are: ‘single’ with one row of corolla segments and ‘semi double’ with two to three rows of segments. The commercial varieties of single tuberose are the following: Calcutta Single, Mexican Single, Royal Rehab etc

Nutritional Requirement

During preparation of the soil, a basal application of FYM at the rate of 12 to 15 tones per hectare should be done to ensure better growth and flowering. Besides, application of FYM tuberose requires good quality of major and micronutrients. A fertilizer mixture containing 6 gms of urea, 16 gms each of single super phosphate (SSP) and muriate of potash per square meter gives satisfactory growth and flowering. The above mixture should be applied in two equal doses – the first dose before planting and the second one, 4 weeks after sprouting of the bulb. The foliar feeding of K and N produces more number of flowers with better quality. An application of 8Kg Zinc Sulphate(ZNSo4), 2Kg Boran and one Kg Sodium molybdate enhances the quality and quality of flower.

Weeding

Weeding should be done after a fortnight, especially in the initial stage of the bulb sprouting and the growth of plants. Hand weeding is eco-friendly but extensive. For chemical control; Atrazine can be applied @1.2 Kg a.i/acre as a pre emergence application. Close planting of 15cmx20cm reduces the weed population in the field.

Mulching

Mulching is primarily done to conserve the soil moisture and check the population of weeds in the field. Black polythene and Gliricidia leaves are most suitable mulches for tuberose cultivation. About 5Kg green leaves of Gliricidia are sufficient for 1mx1m plot to harvest a bumper yield and quality of flowers and spikes. Paddy straw can also be used for mulching in tuberose to conserve soil moisture and to reduce the weed population.

Water Management

Soil moisture is very important factor affecting the growth, flowering and bulb yield of tuberose. Field should be irrigated before planting of bulbs and further irrigation should be avoided until the sprouting of bulbs. The crop should be irrigated at weekly interval in the absence of rainfall. Mulching reduces the water requirement by minimizing the evaporation losses. However, irrigation should be avoided at the maturity stage of bulbs during December-January.

Diseases and insect Pests

Stem Rot

The soil borne diseases caused by Sclerotium rolfsii can be identified with symptoms like appearance of prominent coarse mycelial masses on the leaf surface at or near the soil level. Infected leaves loose green colour due to rotting, which extends to the whole leaf and detaches the affected leaves from the plant. The infected plants should be burnt immediately to check further infection.

Flower bud rot

It is a bacterial disease caused by Erwinia spp. The disease appears mainly on young flower buds and results in dry rotting with brown scorched necrotic discolouration of peduncles. In the advanced stage, buds become shrivel and dry. This disease is mainly spread by thrips. Destroy or burn the infected plant debris to check further infection and adopt remedial measures to control the thrips.

Thrips

Thrips feed on leaves, flower stalk and flowers. They suck sap from these parts and ultimately damage the whole plant. Some times they are associated with a contagious disease known as bunchy top where the inflorescence is malformed. Thrips can be managed by spraying the plants with endosulfan twice at ten days interval.

Harvesting and Packaging of flowers

Tuberose is harvested by cutting off the spikes from the base for decoration or the individual flower is picked from the spike for making garlands. Tuberose flowers are very sensitive to the stresses of storage and transportation, particularly at warm temperatures. The picking of flowers should be done in the morning; harvesting of flowers in the evening and marketing them next day morning should be avoided to prevent weight loss. The flower spike should be cut off with asecateur and be placed immediately in cold water. Loose flowers are packed in bamboo baskets, covered by cloth and transported to the nearby wholesale market for selling. The spikes are graded as per length of the spike, length of the flowering zone and quality of individual flowers. To avoid any loss during transition, the flower bundle should be wrapped in soft tissue paper, polythene or card board boxes. Several preservative solutions can be used to increase the longevity and the keeping quality of tuberose flowers The vase life of cut flowers can be enhanced by putting them in 8% sucrose,50ppm aluminium sulphate ,250ppm boric acid ,50 ppm silver nitrate as the holding solution or by spraying of GA₃(50-100ppm) as growth regulator.

Flower yield

Flower yield varies with variety, plant density and bulb size at planting time and crop, management. A two year experiment with the ‘Single’ variety of tuberose recorded a flower yield of 3,75,000-5, 50,000 spikes/ha during the first year.

Harvesting and yield of bulbs

Harvesting of tuberose bulbs at the proper stage of maturity is important for storage of bulbs and their growth. The bulbs reach maturity when the flower is over and the plant growth ceases. At this stage, the old leaves become dry, plant growth ceases and bulbs are almost dried. About 100 quintal of bulbs can be harvested from one hectare of land.