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 cyc le and developmental stages and seasons. Experimental ponds were maint ained below a pH of 8.5, and one pond was amended with 11.4 kg of nitr ogen per week. Plants were separated into constituent parts after samp ling, dried, and weighed to determine biomass. Early in development, p lants allocated most production to root material, with little increase in average plant size. Once a critical density was reached, plants in creased in average weight and production of daughter plants, with redu ced allocation to roots. At peak density, daughter plant production wa s reduced, but average plant size increased rapidly, resulting in plan t mortality. Waterhyacinth exhibited a positive density dependent grow th pattern early in development, and switched to the negative density dependent pattern after peak density was achieved.