Aquatic Weed Water Hyacinth: A Friend or Foe?

Water Hyacinth

Aquatic Weed Water Hyacinth

A Friend or Foe? 

-Dr. Arvind Singh 

What is water hyacinth?
Water hyacinth is a rooted, floating herb up to 1m tall usually found growing in abundance in fresh water bodies like rivers, lakes, ponds, pools, ditches, tanks, canals and other wetlands. The scientific name of water hyacinth is Eichhornia crassipes and it belongs to the Pontederiaceae family of flowering plants. It is vernacularly known as Jalkumbhi in Northern India.

The petioles of the leaves are inflated containing air, which helps in the floatation of the plant. Flowers are violet-blue in colour. The plant generally reproduces through vegetative propagation. However, sexual reproduction takes place through seed formation. The seeds are viable for up to 30 years.

What are the harmful effects of water hyacinth?

Water hyacinth is native of Central and South America which was introduced by Britishers as an aquatic ornamental plant for the first time in Bengal province in last decades of the 19th century. Thereafter, the plant gradually had escaped the captivity of human cultivation turning itself to a noxious weed infesting the fresh water bodies like ponds, pools, rivers, lakes, canals, tanks, ditches etc. 

Water hyacinth is a weed flora throughout the country and it even infests the water logged paddy fields. Today water hyacinth is the foremost aquatic weed in the entire North-eastern states of India. However, its devastating effect is evident in the state of West Bengal. Therefore, on account of its disruptive effects water hyacinth is nick named as 'Blue devil', 'Terror of Bengal' and ‘Curse of Bengal’.

The plant clogs the water bodies hampering navigation, fishing and agriculture. Water hyacinth depletes the dissolved oxygen content of water and increases the turbidity of water. Water hyacinth also causes the reduction of biological diversity. Its luxuriant growth leads to organic matter accumulation consequently the process of succession is enhanced.

What are the beneficial attributes of water hyacinth?

However, today this invasive weed is considered useful in several ways. On account of its beneficial attributes now water hyacinth is nick named as 'Cinderella of plant world'. Thus this noxious weed of fresh water bodies has the potential to provide several beneficial services to human beings.

Water hyacinth is rich in protein content hence it is used as livestock feed in Assam and West Bengal. Moreover, it is used as bedding material for mushroom cultivation, as compost for promotion of fish food planktons, in air layering, as a source of cellulose, in basket work, and in rough paper production. It is also used in making wicker and chair bottoms in the states of North-eastern India.

Studies have revealed that water hyacinth is useful to plant for Phytoremediation. The latter is an emerging eco-friendly technology for the removal of pollutants from the environment using plants. This plant species has the ability to absorb toxic substances from the polluted water. The roots of the water hyacinth absorb, precipitate and concentrate toxic metals (Pb, Co, Zn, Mn, Ni, Cu, Cd, Fe, Hg, Se and Ag) from polluted effluents (Rhizofilteration). 

Hence, water hyacinth can be used in the treatment of polluted water to remove the pollutants. Thereafter, the pollutant-loaded plants can be removed from the site and destroyed by burning or burying them beneath the ground surface. Water hyacinth can also be used in waste water treatment system for the removal of leached nutrients from waste waters.

The root and leaf extracts of water hyacinth have been reported to enhance seed germination and seedling growth in Cassia alata.

Water hyacinth has the ability to serve as potent green manure as it is an accumulator of high concentrations of mineral nutrients in its body (especially N, P & K). Therefore, it can be used as a green manure to improve the fertility status of the soil. The harvested water hyacinth plants infesting the nearby water bodies can be spread on the field and ploughed. 

This would substantially increase the nutrient and organic matter content of the soil resulting in an increase in fertility of the soil. The increase in organic matter content would not only increase the water holding capacity of the soil but would also promote the useful floral and faunal wealth of the soil. Water hyacinth can also be used as compost and as mulch.

Water hyacinth can serve as a raw material for the biogas generation in biogas plants of rural areas. Biogas is produced by the anaerobic fermentation of waste material or biomass. Biogas consists of 50-70% methane (CH4) and 30-40% carbon dioxide (CO2) and traces of hydrogen, nitrogen and hydrogen sulphide. 

The calorific value of biogas is about 23-28 MJ/meter square. In India, dung has traditionally been used as a raw material to run the biogas plants in rural areas. Hence the use of water hyacinth as a raw material would save the dung which could be diverted to agricultural fields as farmyard manure.

How to control the water hyacinth?

Chemicals like Paraquat, 2, 4- Dichlorophenoxyacetic acid and Aminotriazole are quite effective herbicides to destroy water hyacinth.

Weevils like Neochetina bruchi and Neochetina eichhorniae and the moth Niphographta albigultalis are effective as biological control agents to control water hyacinth. Weevil Neochetina eichhorniae reduces plant height, weight and root length. 

Conclusion:

Conclusively it can be said that water hyacinth is a very useful flora, and thus its large scale exploitation for various purposes would not only provide beneficial services to human beings but would also be helpful in the control of this noxious weed flora.
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Dr. Arvind Singh is M. Sc. and Ph. D. in Botany with an area of specialization in Ecology. He is a dedicated Researcher having more than four dozen 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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