Biomass and productivity of water hyacinth and their application in control programs.

Abstract

Water hyacinth is controllable if management programs take account of plant dynamics and factors that influence plant behaviour. The project for reclamation of water bodies in Mexico considered water hyacinth standing crop, coverage and growth. The method proposed served to characterise the initial population and monitor the control process. The growth model used was reliable in predicting the effective reduction in the weed in response to control pressure. Change in growth over an annual cycle was characterised by a sigmoid curve. The maximum relative percentage growth rate was 9.34%, with a duplication time of 7.4 days from April to June. During winter, growth decreased by up to 90%. In a dam, 144 t/ha/year of dry matter was produced, characteristic of water plants with a high nutrient content. The water hyacinth population can be reduced by 90 % through water level management and mechanical destruction. For example, approximately 3600 t/day was removed over 181 days to reduce the infestation to manageable levels. Physical, chemical and biological methods are used to maintain these levels, but input of urban and industrial contaminants must be controlled for long term rehabilitation. OUTBREAKS of aquatic plants is the result of changes in the physical, chemical and biological conditions brought about by the uncontrolled flow of nutrients