Aquatic Plant Control Research Program. Seasonal Biomass and Carbohydrate Distribution in Waterhyacinth: Small-Scale Evaluation

Abstract : A better understanding of aquatic macrophyte growth cycles and identification of physiological weak points in those cycles are essential for improving the effectiveness of present control techniques of nuisance aquatic vegetation. Application of control tactics at weak points in the target plant's growth cycle should maximize control effectiveness. The objectives of this study were to identify potential physiological weak points in waterhyacinth (Eichhornia crassipes (Mart.) Solms) based on seasonal carbohydrate allocation. May/June and late October were the two periods of extensive ramet production. Highest carbohydrate levels were found in stem-bases from July through November, and in mature leaves in other months. Roots and young petioles had lowest concentrations of starch as compared with other plant parts. Waterhyacinths store maximum carbohydrates in the stem-bases during the September to October period. Starch and sucrose were the main components of carbohydrate reserves in stem-bases. Information on seasonal biomass and carbohydrate distribution demonstrates the important role of stem-bases in the winter survival of waterhyacinth. Potential weak points in the growth cycle of waterhyacinth include the period shortly before mid-September or mid-October, when plants are actively translocating carbohydrates to stem-bases, and is early spring, when weather is warm enough for young ramet emergence and carbohydrates in stem-bases are low.