Workshop - University Grants Commission - Sri Lanka

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1.3 Reproduction
Water hyacinth reproduces sexually by seeds and vegetatively by budding and
stolen production. Daughter plants sprout from the stolons and doubling times have
been reported of 6-18 days. The seeds can germinate in a few days or remain
dormant for 15-20 years. They usually sink and remain dormant until periods of
stress (droughts). Upon reflooding, the seeds often germinate and renew the growth
cycle.
1.4 Response to Herbicides
The use of herbicides to control water hyacinth is common. It can be controlled by
the use of the aquatic herbicides 2, 4-D or diquat.
1.5 Response to Mechanical Methods
Mechanical controls such as harvesting have been used in Sri Lanka, but are
ineffective for large scale control, very expensive, and cannot keep pace with the
rapid plant growth in large water systems.
1.6 Biocontrol Potentials
Three insects have been released for the biological control of water hyacinth. These
include two weevil species (Neochetina spp.) and a moth (Sameodes albiguttalis).
Unfortunately large scale reductions in water hyacinth populations did not occur.
Instead insect predation reduced plant height, decreased the number of seeds
produced, and decreased the seasonal growth of the plants. This, in turn, allowed
better boat access into plant mats, reduced use of herbicides, and resulted in less
plant problems.
The present study was carried out with the following objectives in order to use them
in compost preparation:
1. To minimize the problem of Eichornia crassipes in water bodies.
2. To produce bio-compost with low cost and high nutritive plant materials.
1.7 Compost Using Water Hyacinths
Compost is the product resulting from the controlled biological decomposition of
organic material. More specifically, compost is the stable, humus-like product
resulting from the biological decomposition of organic matter under controlled
conditions. A wide range of materials may be composted, but they must consist of