Polyantes tuberosa Family:

Polyantes tuberosaFamily:Amaryllidaceae,Tube roseThe tuberose occupies a very selective and special position among the ornamental bulbous plants for its beauty, elegance and sweet pleasant fragrance. It has a great economic potential for cut-flower trade and essential oil industry. Due to their great demand, it is currently cultivated in most of the tropical and sub-tropical countries of the world.

At present the total area under tuberose cultivation in the country is estimated to be about 20,000 hectare.Morphology and Classification

Tuberose is a half-hardy, bulbous perennial perpetuating itself through the bulblets. Bulbs are made up of scales and leaf bases and the stem is a condensed structure which remains concealed within scales. Roots are mainly adventitious and shallows. The leaves are long, narrow, linear, grass-like, light green, and arise in rosette. The flowers have a funnel shaped perianth and are fragrant, waxy white, about 25 mm long, single or double and borne in a spike. The terminal flower spikes arising from the bulb produce flowers for a number of days. Stamens are six in number, anthers dorsifixed in the middle, ovary 3 locular, ovules numerous and fruits are capsule.. Species and Cultivars

A. Species .Polianthes is a monotypic genus TThe genus contains about a dozen of species but they are not clearly distinct. Nine of the species so described had white flowers, one was white-and-red and two are red. All are found growing wild with the exceptions of P. tuberosa which has never been found anywhere except under cultivation. The only close relative of P. tuberosa is believed to be Polianthes gracilis. The description of important species is given here.

1. Polianthes tuberosaIt is an erect herb, 60-120 cm high with stout and short bulbs; leaves basal, 6 to 9 in number, 30-45 cm long, about 1.3 cm wide, linear, bright green, reddish near the base, flowers funnel shaped, waxy white, the tube bent only near the base, filaments attached on upper part of corolla, fragrant in long terminal racemes.2. Polianthes polustris3. P. durangensis4. P. montana5. P. longiflora6. P. platyphylla7. P. graminifolia -This deep red species is very common in Mexico. 8. P. geminiflora9. P. gracilis (P. tuberosa vas. gracilis)10. P. pringlei

B. Cultivars

There are three types of tuberose: i. single with one row of corolla segments;ii. semi-double bearing flowers with 2-3 rows of segments;iii. double having more than three rows of corolla segments.

Singles Calcutta single, Hyderabad single, Prajwal, Rajat Rekha and swarma Rekha (NBRl, Lucknow) .Semidouble-Double-Vaibav,Hyderabad double,Calcutta double IV. Climate

Tuberose grows in mild climate without extremes of high or low temperatures even though it can be grown under a wide range of climatic conditions.commercial cultivation of tuberose is mainly confined in warm humid areas with average temperature range from 200 to 350 centigrade. For its luxuriant growth, it requires high humidity and a temperature around 300 centigrade. Temperature above 400C reduces the spike length and quality of the flowers. Very low temperature and frost also damage the plants and flowers. Tuberose grows well in sunny situation.

V. Soil

The tuberose grows in a wide range of soils. Its cultivation can also be extended economically in almost unproductive soils affected by salinity and alkalinity. Loam and sandy loam soils having a pH range from 6.5 to 7.5 with good aeration and drainage are considered suitable for its cultivation. The soil should be rich in organic matter and retain sufficient moisture for proper growth. However, it is suggested that heavy soils, where rice is cultivated should be preferred to light red soils. For cultivation in pots, a mixture of garden soil, FYM and leaf mould in the proportion of 2:1:1 should be used.

VI. Propagation

Tuberose is mainly propagated vegetatively by means of bulbs. Seeds, if produced, are difficult to germinate and are seldom used for raising plants. Although, not very common, propagation may also be done by the division of bulbs. To get virus-free material or for a very rapid multiplication, the propagation is done through tissue culture.B. Vegetative propagation

The tuberose can also be propagated vegetatively by the following methods.1. Propagation by bulbsThis is the most common method practised commercially for the multiplication of tuberose. However, care should be taken in the selection of suitable bulbs. Spindle-shaped bulbs free from diseases and having an average diameter of 1.5 cm or above should always to preferred to conical or flat bulbs. The maximum production of bulbs can be obtained by planting the early and to grow as late as possible.

2. Propagation by division

Another method of propagation is by using bulb segments. The success, depends on the size of the bulbs and only the segments from large bulbs (2 cm or more in diameter) regenerate well. Bulbs are cut into 2-3 vertical sections, each containing a bud and a part of the basal plate. Each of these sections is treated with fungicide and planted vertically in a rooting medium with their tips just showing above the surface. A moderately warm temperature, slightly higher than for mature bulbs should be maintained. New bulblets along with roots develop from the basal plate. At this time they are transferred to the ground to continue growth.

C. Micropropagation

The conventional method of propagation through bulbs is rather slow to meet the growing demand and, therefore, clonal propagation through tissue culture may be utilized for rapid and large-scale multiplication.

CultivationA. Site selectionFor optimum growth and high yield of flowers it is preferable to choose a place having plenty of sunlight. A little shade towards the later part of the afternoon is desirable in hot summer If there is too much shade, the plants grow tall and lanky and the flowering is adversely affected. Tuberose is sensitive to wet feet, hence drainage should be good, water- logging even for a short period damages the root system and affects the growth and flowering

B. Soil preparation

Land preparation is very important for the cultivation of tuberose. The field should be worked deep to a good tilth and properly manured. If the soil is not thoroughly prepared and contains soil clods or undecomposed organic matter, bulb production is affected and it also reduces the yield and quality of flowers. Well rotten cow dung or farmyard manure @ 50 tonnes/ha, should be incorporated with the soil about a month before planting. Care should be taken to make the land free from weeds.

C. Bulb selection and planting

Selection of good planting material'is necessary for obtaining higher yield and good quality of flowers. It has been observed that fresh bulbs if planted, lead only to profuse vegetative growth_but little flowering, and a storage for few weeks is essential for better growth and flower production. Therefore, clumps of bulbs should be dug out of the soil when plants cease to grow and are stored in the well ventilated semi-shady place for at least one month before planting. The bulbs before planting, should be treated with fungicide, and Blitox may be used for this purpose. They should carefully be placed upright by land and covered with soil. Clumps as such should never be planted as the plants grow vegetatively rather than produce flowering spikes. For pot cultivation, 2-3 bulbs are planted in the centre of a 20 cm pot.

1. Bulb size, depth and planting time

Larger bulbs were found to take more time for sprouting. This might be due to the presence of more layers of membranes scales which interfered exchange of gases and inhibited metabolic process. Plant height and number of leaves per bulb also showed gradual increase with the increase in bulb size-up to a certain limit.Bulb size also influences flowering. Larger bulbs cause early flowering and give higher yield of spike and flowers. The number of flowers per spike, flower quality, daughter bulb production etc were also found to be related to bulb size.

In general, bulbs having diameter having 2.0 to 3.0 cm are suitable for planting. It has been observed that planting of bulbs having 2.6 to 3.0 cm recorded the highest yield of spikes (15.1 Iakhs/ha) and flowers (30.1 tonnes/hectare).

Planting depthPlanting depth also marketedly influences growth and production of flowers. It may vary from 4.0 to 7.0 cm depending on the size of the bulb, mature of soil as well as the growing regions. The bigger is the bulb, the more is the depth. Similarly, in sandy soil, planting is deeper as compared to clay soil. Planting of bulbs at greater depth delays the appearance of shoots. In sandy loam soil, planting of bulbs at the depth of 6.0 cm is recommended.

Planting seasonTuberose is generally planted inA) February-March in the plains B)April-May in the hills.

Southern India- July-August.

Planting of bulbs in the month of April has shown to record the highest yield of spikes and flowers in the cv. single.

Sequential planting may be practiced to obtain flowers almost throughout the year, if the temperature is not very low in the winter months.

Replanting is necessary after 3 years

2. Planting distance

Plant density influences the yield and quality of flowers and bulbs obtained per unit area. Higher plant density has been found to produce greater yield of spikes, flowers and bulbs. The planting distance varies in different regions. Similarly the quantity of planting material required for an area is also variable.D. Irrigation

Soil moisture is an important factor affecting growth and flowering in tuberose. Irrigation should be done before planting to provide optimum moisture for sprouting and further irrigation should be avoided until the bulbs have sprouted .Too much moisture in the soil at the time of sprouting results in the rotting of bulbs and similar condition during flowering adversely affects the development of spikes and flowers. The frequency of irrigation depends upon soil type, stage of growth and weather conditions. The tuberose fields should be irrigated at interval of 10-15 days, if the weather is dry.

summer months (April to June) - irrigated at weekly interval winter at 10-day interval. In an investigation on the effect of irrigation frequency on the growth and flowering, it was observed that plants of cv. Pearl irrigated at 40 11m2 every 7 days were large, Flowered earlier and produced large bulbs than those irrigated at every 14 days.

The effect of different watering rates and mulching on tuberose for bulb enlargement was studied and found that drip irrigation at 2000-3000 m3/ha gave the best yield of 30-32 bulbs/m2 of planting size.

Mulching with black polythene does not reduce the water requirement.