2. Costus
S.N. :- Costus speciosus
F. :- Costaceae
Economic part:- Rhizomes
Active constituent:- Rhizomes contain Diosgenin (2.12%) out
of total Sapogenins (3.86%), curcumin and curcuminoids
7. Medicinal uses
Leaves
Leaves are also crushed and used in a poultice applied to the
head.
Plant
In Malaysia , the plant is boiled in water to prepare a
decoction, which is used to bathe a patient with high fever
Decoction of the plant are applied as a lotion for smallpox
Stem
The scrapings of the stem are applied to leprous skin
8. Shoot
Juice of the tender shoots or pith is squeezed into the eye for
ailments of the eye
Rhizome
The juice of the fresh rhizome is taken as a purgative
In India, the rhizome is powered and taken for colds,
rheumatism and pneumonia. It is also believed to be a tonic,
depurative and aphrodisiac
In Java, the rhizome is used after confinement, and also to
treat syphilis
9. Diosgenin, widely used as starting material in commercial
production of steroidal hormones,
It is chiefly obtained from certain species of Dioscorea of
which Dioscorea deltoidea constitutes the main Indian raw
material.
This source, however, has limitations in ensuring large supplies
on a sustained basis due to its restricted distribution in few
localities in North-West Himalaya and poor response to
domestication.
It become necessary to search for an alternative botanical
source which could be easily cultivated under a wide range of
agro-climatic conditions and provide the industry with a raw
material at comparative low price and on sustained basis
10. A number of plants were found to contain steroidal
sapogenins but none could satisfy all the criteria of
such substitute.
The report of the presence of diosgenin in the
rhizomes of Costus speciosus (Family:
Zingiberaceae) raised the hope of developing such a
source as the plant was widely distributed in India.
11. Origin and Distribution
Costus is native to Indo-Malayan regioon
In India the plant naturalizes in Sub-Himalayan tract, in parts of
central India and in the Western Ghats of Maharashtra, Karnataka
and Kerala.
Two varieties of C.specious viz., nepalensis found only in Nepal
and Arunachal Pradesh and var. argyrophyllus having a wide
distribution in India have been described.
12. Description of the plant
The Plant has broad, lanceolate, dorsally silky leaves, borne
spirally on stout, erect or sometimes ascending stems. The flowers
are white, with a large incurved lip.
These are clustered in terminal globose heads characterized with
large and shiny brown or red bracts.
Both diploid (2x=18) and tetraploid forms occur in nature.
C.speciosus perenniates through underground
13. Rhizome which lies a few centimeters below the soil surface.
The rhizome is differentiated into nodes and internodes.
The vegetative activity above the ground lasts for about 7-8
months.
Stems sprout during the month of April, flowering commences
during July and continues till the end of September,
The fruits ripen during the middle of November, after which the
leaves are shed and majority of the canes start drying up.
The underground portion remains dormant from December to
March.
14. Soil
The plant can be grown on a variety of soils ranging
from coastal alluvium to heavy brown forest type.
It grows more luxuriantly on alluvial soils having a sandy
to clay loam texture with a pH of 5.7-7.5.
15. Climate
It can be grown from sea level to about 1500 m elevations. But the areas
situated at elevations between 400 and 600 m above mean sea level.
Having a subtropical climate with an rainfall ranging between 1000 and
1500 mm bear good quality material. High humidity and minimum
temperature 13° C is best for its cultivation.
A well marked dry period between monsoon precipitation results in
higher diosgenin content in naturally occuring plant populations.
Coastal regions and regions with high annual rainfall and humidity
throughout the year bear poor quality raw material in terms of diosgenin
content.
16. Cultivation :
Propagation
Although the plant can be propagated from seeds, stem cuttings and
rhizomes
Commercially it is being propagated only through rhizome cuttings.
Selection of rhizomes for planting is however important. The rhizomes
have a number of nipple shaped buds most of them being concentrated
around the stem scars and the tips.
The formation of buds on the rhizomes is poor during April. Cuttings
of rhizome pieces for propagation should have at least two viable buds.
The rhizome pieces weighing around 40g should be selected.
17. Propn cont….
It can also be grown through seeds. Costus seeds are
dispersed by birds when they feed on the fruits. The
percentage of seed germination is about 62%.
Seed rate: 2000 to 2400kg/ha. Rhizomes required.
18. Land preparation
Land is ploughed 2-3 times and soil is brought to a fine tilth.
FYM at the rate of 15 tonnes is applied and mixed well with the soil.
Furrows are opened at 50 cm apart.
Planting :
The rhizome pieces are placed at a depth of 8-10 cm taking care to
place the eye buds facing upwards, horizontally in rows at 50 cm apart
and covered with soil.
The crop is irrigated immediately after planting. Thick sized pieces
show a slow rate of sprouting till 40-45 days of planting.
This is due to eye buds being dormant on these rhizome pieces which
take a longer time to develop especially in case of the crop planted
during April. After 70-75 days about 90-95 percent sprouting is obtained
19. Desiccation of young sprouts has been observed during hot summer
months, necessitating liberal water supply during this period.
Best period of planting is from 3rd week of April to 3rd week of May.
Rhizomes planted during June and July complete germination within 60
days but yields obtained are low as the crop has a shorter growth period
in the first year before dormancy sets in.
The active vegetative growth period of crop is from July to Mid
September and maximum tuberization takes place between September to
November before dormancy sets in.
The effect of planting on ridges versus flat beds indicated that there
was no significant difference in yield due to the method of planting
although a higher yield of fresh rhizomes was obtained in the crop
planted on ridges.
20. Manures and Fertilizers:
It is a rhizomatus crop and to compensate the biomass
production, heavy manuring is required.
In a trial conducted at Vallanikkara, the tentative optimum
dose for obtaining the maximum yield of diosgenin was
observed to be 45 kg N, 30 kg P2O5 and 30 kg K2O along
with 15 tonnes of FYM per hectare.
The farm yard manure and half dose of phosphorus and potash
are applied in 2 split doses at 20 and 60 days of planting, the
remaining half dose of phosphorus and potash is given along
with the second dose of nitrogen after 60th day of planting.
21. Irrigation :
The crop requires a liberal supply of water for successful
growth. The crop planted during April and May requires to
be irrigated atleast two to three times a month till the
outbreak of monsoon.
As September to November is the period of miximum
tuberization atleast two irrigations should be given.
During the dormancy period (December to March), if
winter rains are scanty, there is need for irrigation.
22. If moisture conditions are adequate it has been observed that
the crop sprouts towards the end of March or early April.
With a liberal supply of irrigation during the hot summer
months excellent crop growth is observed during these months.
Thus, for a crop to be harvested after a period of 17 to 18
months, 14 to 17 irrigations are required.
23. Weeding and Inter-culture
One weeding during the sprouting period of the crop followed
by two more keeps the crop fairly free of weeds.
During the period of active vegetative growth (July to
September) most of the weeds are suppressed. If the monsoon
is erratic, there is need to remove weeds at least once.
Weeding once or twice during the dormant season helps in
better sprouting of the crop during the next season.
During the second year of the crop, the inter-row space
between plant is covered up by the canes and only two to three
weeding are necessary before the crop is harvested in August or
September
24. Pests and Diseases
There are no major pests which affect this crop. However,
following are some diseases which are observed to affect the crop.
1. Rhizome rot
It is caused by Phytophthora solani and develops very fast from July
to August, in the rhizomes kept in storage after the harvest.
Initially symptoms start from the tip from the injure portion of the
rhizomes. Subsequently, the rhizome becomes light brown and gives
offensive odour.
Properly harvested rhizomes without injuries can be stored for long
time. No chemical control has been worked out.
25. 2. Pythium rhizome rot
It is caused by Pythium spinosum.
In this disease, the infection in the plant starts from injured
portion of the rhizomes and in later stages rhizomes turn into
dirty brown in colour, the leaves become yellowish brown
and finally dry off.
Selection of rhiozmes from the healthy crop and dipping the
rhizomes in fungicidal solutions like Benlate, Bavistin or
Dithane-z-78 has been recommended to control the disease.
26. 3. Leaf blight
It is caused by Curvularia paradisii. It is very severe from July to
September.
The symptoms develop on the leaf lamina as a small, spherical to
irregular spots, light brown in colour, and in advanced stages they
become dark brown upward.
Curling of young leaves towards upward is very common. In
advanced stages all the leaves fall down leaving bare stem in the
field.
This pathogen can be effectively controlled by spraying 0.3 per
cent Dithane M-45 at fortnightly intervals.
27. Harvesting and Yield
It is observed that diosgenin content is maximum when the
crop is in an active stage of vegetative growth, and when it is
of 16-17 months old.
Two operations viz., harvesting the aerial shoots and digging
out the rhizomes are required to complete the harvesting in
costus.
After harvesting the aerial shoots, the most satisfactory and
economic method to dig out the rhizomes is to run the tractor
drawn cultivator crosswise twice or thrice in the field and
simultaneously collect the uprooted rhizomes manually.
A negligible amount of damage is caused to rhizomes during
the operations.
28. The harvested rhizomes are spread out for a few days and the
earth sticking on the rhiozmes is removed or alternatively the
rhizomes are washed under the jet of water from the tube well
discharge pipe.
The rhizomes have to be chopped and dried before diosgenin
can be extracted.
Hand chopping is time consuming and costly, so chopping by
mechancial means has to be resorted to.
Several methods have been tried but the ordinary wheat
theresher with a little modification is found satisfactory for
chopping the fresh rhizomes.
Very fine chopped material dries quickly (2-3 days).
29. An yield of 28 to 30 tonnes per hectare of fresh rhiozmes may
be obtained in the Ist season crop (8-9 months) harvested in the
dormant season, but the diosgenin yield would be poor.
On account of low recovery. The crop should therefore be
harvested after 17-19 months of planting for better yield of
fresh rhiozmes and diosgenin content.
From the second season crop (17-19 months), an yield of 50
tonnes of fresh rhizomes from which 75-125 kilgrams of crude
diosgenin may be obtained.
