The Other Side of the Coin
-Dr. Arvind Singh
Parthenium hysterophorus is an exotic annual herb belonging to the Asteraceae family of the flowering plants. It is native of Tropical America where it is known as ‘Santa Maria’ ‘White top’ and ‘Rag weed’. In India Parthenium hysterophorus is commonly known by the name ‘Congress grass’ and ‘Carrot weed’ and is vernacularly called as Gazar ghas’ and Chamak chandni.
It was introduced in seed form as a contaminant of wheat imported from Mexico. Parthenium hysterophorus was first reported from India in 1956, growing as stray plants at waste places in Pune, Maharashtra. Since then the weed has spread fast and has been reported found almost all over India. In India, this weed grows along roadsides and railway tracks, on uncultivated lands and wastelands, in industrial areas on the sides of the open drainage system and irrigation canals, besides invading agricultural crop fields.
What are the Salient Features of Parthenium hysterophorus?
Parthenium hysterophorus is a tall-growing, deep-rooted, much-branched dicotyledonous plant attaining a meter height at the fully flowering stage. The plant bears small white flower aggregated together to form the capitulum inflorescence. At maturity, the capitulum is transformed into cypsela type fruit which bears numerous seeds. The plant is chiefly propagated through mild seeds. It has the ability to produce about 154,000 seeds per square meter. A single plant of Parthenium hysterophorus can produce 620 million pollen grains and about 15,000-25,000 seeds.
The seeds are fluffy, very small in size and light in weight easily dispersed by wind, water and through various human activities. Parthenium hysterphorus has the capacity to regrow from the cut or broken parts. Absence of natural enemies like insects and diseases are the two important factors responsible for its rapid spread in India. The weed is often avoided by grazing animals. In India, this weed starts appearing at the middle of spring i.e. at the end of February in flushes and continues to appear till the onset of winter. The luxuriant growth of congress grass is seen during July and August, whereas in winter it remains dormant by forming rosette appearance.
Parthenium hysterophorus is adapted to environmental extremes and prefers moist, shady and nutrient-rich habitats. The plant is neutral both them periodically and photo periodically. It is a rapid colonizer eliminating other herbaceous flora in its vicinity. The plant remains in flower during most part of the year because of its high ecological amplitude.
What the Harmful Effects of Parthenium hysterophorus?
Parthenium hysterophorus is considered as a noxious weed because of its invasiveness, the potential for spread, the allelopathic effect on other plants, strong competitiveness with crops and health hazards to human and livestock population.
The pollen grains of the weed are allergic causing bronchitis, asthma, rhinitis, conjunctivitis, hay fever, sinusitis, common cold, pain in the neck and even depression in human beings. Frequent contact with the weed causes dermatitis, eczema, pallertons is and gangrene. This weed is harmful and even fatal to the livestock population grazing in the area infested by it. These animals suffer from itching, fall of body hairs, discolouration of skins, inflamed udder etc. It has also been reported that congress grass is responsible for the development of bitter taste in milk if cattle graze in an area infested by Parthenium hysterophorus or are fed on grass mixed with this weed.
As a weed of agricultural crops, Parthenium hysterphorus has marked effect on growth and colonization of Rhizobia (nitrogen-fixing bacteria) in pulse crops. This may reduce nodulation up to 60% thus substantially reducing the nitrogen-fixing ability of the pulse crops.
Congress grass enjoys a monopoly in its growing habitat due to allelopathic property. The weed releases growth inhibitors in the soil which suppresses the growth of other herbaceous vegetation in its vicinity. Thus it grows in dense pure stands over a large area by replacing the native plant species.
Besides aforesaid ill effects, the weed also causes several other problems like blockage of common pathways and reduction in the aesthetic values of parks, gardens and residential colonies.
What are the Beneficial Attributes of Parthenium hysterophorus?
Despite of its harmful effects on biodiversity, crop yield and human and livestock health, the Parthenium hysterophorus possess several beneficial attributes. The plant medicinally important and may also be helpful in increasing the crop yield. This weed can also be used as raw material for biogas plants.
Since Parthenium hysterophorous possess medicinal properties, hence it can be used as remedy for several diseases. The word ‘Parthenium’ has been derived from a Latin word ‘parthenice’ which also corroborates its medicinal significance. Traditionally local inhabitants of Central America frequently use Parthenium hysterophorus as ethnomedicine.
The entire plant of Parthenium hysterophorus has a bitter taste and is stimulant and antihysteric. The plant is equally important for both homoeopathic and allopathic systems of medicine. In the homoeopathic system of disease treatment, the whole plant is collected in the flowering stage and subsequently used for drug preparation. An infusion of Parthenium hysterophorus is effective against consumptive cases and in infirmities of the mother. It is used as febrifuge, emmenagogue and tonic in the allopathic system of disease treatment. The decoction of the root is useful in dysentery, amoebic dysentery and in hepatic amoebiasis.
The ‘parthenin’ (a major sesquiterpene lactone) extracted from the whole plant of Parthenium hysterophorus is pharmacologically active against rheumatism and neuralgia and is externally applied in skin diseases. The juice of the leaves is effective against earache.
Parthenium hysterophorus is well known for its allelopathic attributes and it has been well established that allelopathy could be used to increase crop yield, to minimize crop yield expenses and to get rid of from the use of agro-chemicals that deteriorate the environmental quality.
Seed germination is problem related to crop production. Studies have revealed that extracts and leachates of Parthenium hysterophorus leaves help in the seed germination of linseed (Linum usitatissimum). Several other aspects like seedling vigour, growth and pest management of many agricultural crops like rice (Oryza sativa), wheat (Triticum aestivum), groundnut (Arachis hypogaea) and maize (Zea mays) by using extracts of Parthenium hysterophorus is in experimental stage.
The dried leaves of Parthenium hysterophorus are effective against storage grain pests. The decoction of the leaves is used as flea-repellant. Leaves of Parthenium hysterophorus yield some essential oil.
Parthenium hysterophorus may be utilized as a raw material for biogas plants, as effective binding agent to check soil erosion and as a component of vermicompost. It may also be used as green manure to ameliorate the physicochemical properties of the soil.
How to Control Parthenium hysterophorus?
The weed Parthenium hysterophorus defies all control measures, however following methods can be used to keep down the weed. Herbicides like Atrazine, 2, 4-Dichlorophenoxyacetic acid, Paraquat, Glyphosate, Diuron and Dalpan should be used to suppress the weed up to some extent as these are found partially effective against the weed. The leguminous plants like Cassia sericea, Cassia uniflora and Cassia tora have been found to replace this harmful weed.
Hence these pants should be used as replacement species to eliminate the weed. Parthenium hysterophorus growing in agricultural fields should be destroyed early in the month of June by ploughing the field before setting of flowers. Burning of this weed should be done during early November when the whole plant dry and seeds mature.
Presently biological control is the most effective way of controlling this weed through Mexican beetle (Zygogramma bicolorata). This insect was introduced to India from South America. Detailed host-specificity tests under quarantine conditions confirmed the safety of beetle to cultivated crops in the country. Both adults and larvae of this beetle are capable of feeding on the leaves of Parthenium hysterophorus.
Larvae after hatching start to feed on soft growing leaves, first attacking the terminal and auxiliary bud and later the leaf blades, thus checking the plant growth and flower formation. Adults voraciously defoliate the plant. The beetle cut immature flowers in an effort to chew soft tissues beneath the flowers. The completely defoliated plants start to show the symptoms of die back and gradually get killed.
Conclusion:
It can be concluded that though Parthenium hysterophorus is a notorious weed detrimental to crop yield, biological diversity, human and livestock health, yet it possess several beneficial attributes. Therefore, use of this weed plant for various purposes would not only benefit the society but would also be helpful in the control of this terrible weed.
References:
1. Aneja, K. R., S. R. Dhawan and A. B. Sharma 1991. Deadly weed Parthenium hysterophorus Linn. and its distribution. Indian Journal of Weed Science 23 (3 & 4): 14-18.
2. Dominguez, X. A. and A. Sierra 1970. Isolation of a new diterpene alcohol and parthenin from Parthenium hysterophorus Planta Medica 18: 275-277.
3. Ghosh, D. 2004. Problematic parthenium. Science India 7(6): 38-40.
4. Hamilton, F. 1997. The Flora of Homoeopathica, B. Jain Pvt. Ltd. New Delhi, India pp. 147-149.
5. Lindley, J. 1985. Flora Medica. Ajay Book Service, New Delhi, India pp. 462.
6. Nath, R. 1981. Note on the effect of Parthenium extract on seed germination and seedling growth in crops. Indian Journal of Agriculture Science 51(8): 601-603.
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8. Oudhia, P. and R. S. Tripathi 1999. Allelopathic effects of Parthenium hysterophorus, Lantana camara and Ageratum conyzoides on germination and seedling vigour of wheat and selected rabi crops. In: World Congress on Allelopathy - Critical Analysis and Future Prospects (Ed. A. U. Mallik, Lakchead University, Ontario, Canada pp. 142.
9. Oudhia, P., S. S. Kolhe and R. S. Tripathi, 1997. Allelopathic effects of Parthenium hysterophorus L. on germination of linseed. Indian Journal of Plant Physiology 2(4): 327-329.
10. Raizada, M. B. 1976. Supplement to the Flora of Upper Gangetic Plains and of the Adjacent Siwalik and Sub-Himalayan Tracts. Bishen Singh Mahendra Pal Singh, Dehra Dun, India.
11. Raju, R. A. 1998. Prevalent Weed Flora in Peninsular India. Allied Publishers Ltd., New Delhi, India.
12. Rao, R. S., 1956. Parthenium hysterophorus L. a new record for India. Journal of Bombay Natural History Society 54: 218-220.
13. Sharma, G. L. and K. K. Bhutani 1988. Plant-based antiamoebic drugs, Part II. The amoebicidal activity of parthenin isolated from Parthenium hysterophorus. Planta Medica 54: 20-22.
14. Singh, A. K. and S. Singh 2008. A morpho-taxonomic observation of seedlings of Parthenium hysterophorus L. A well known exotic weed. Indian Journal of Forestry 31(2): 197-200.
15. Singh, U., A. M. Wadhwani and B. M. Johri 1996. Dictionary of Economic Plants in India. Indian Council of Agricultural Research, New Delhi, India.
15. Singh, U., A. M. Wadhwani and B. M. Johri 1996. Dictionary of Economic Plants in India. Indian Council of Agricultural Research, New Delhi, India.
16. Uphof, J. C. 1959. Dictionary of Economic Plants, Hafner Publishing and Company, New York.
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Dr. Arvind Singh is M. Sc. and Ph. D. in Botany with area of specialization in Ecology. He is an dedicated Researcher having more than four dozen of published Research Papers in the Journals of National and International repute. His main area of Research is Restoration of Mined Lands. However, he has also conducted research on the Vascular Flora of Banaras Hindu University Main Campus, India.
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