GROWTH AND BIOMASS ALLOCATION PATTERNS DURING WATER-HYACINTH MAT DEVELOPMENT

Two experiments in ponds were conducted to determine growth rates and biomass allocation patterns of waterhyacinth during different life cycle and developmental stages and seasons. Experimental ponds were maintained below a pH of 8.5, and one pond was amended with 11.4 kg of nitrogen per week. Plants were separated into constituent parts after sampling, dried, and weighed to determine biomass. Early in development, plants allocated most production to root material, with little increase in average plant size. Once a critical density was reached, plants increased in average weight and production of daughter plants, with reduced allocation to roots. At peak density, daughter plant production was reduced, but average plant size increased rapidly, resulting in plant mortality. Waterhyacinth exhibited a positive density dependent growth pattern early in development, and switched to the negative density dependent pattern after peak density was achieved.