Excess aluminum tolerance of the common water-hyacinth (Eichhornia crassipes) under greenhouse conditions

Aluminum is a heavy metal toxic to living organisms and is released into soils with a strong acidic composition. The foating aquatic weed Eichhornia crassipes (Mart.) Solms is reported as the most widespread invasive vascular plant in the world and is distributed all over Colombia ranging from sea level to the cold Andean highlands. As a consequence of the solubility of [Al.sup.3+] in soils, it fows into fresh water sources where E. crassipes grows as an invasive plant. A greenhouse study was conducted in Tunja, Colombia, with the objective of evaluating the growth of aquatic weed in an aqueous substrate with [Al.sup.3+] content similar to those recorded in lakes (0.0, 0.2, 0.4, 0.6, and 0.8 mg [L.sup.-1] [Al.sup.3+]). Biomass production, leaf area, evapotranspiration, water use efficiency, and other allometric variables were evaluated. An increase of 18.2% in the transpiration rate and a reduction between 9.7%-41.8% in the leaf area were found. The latter reduced the value of variables such as the specific leaf area between 9.9%-34.6% and leaf area ratio between 16.7%-40.4%. However, the total dry weight, DM partitioning, root to shoot ratio, leaf weight ratio, and the absolute and relative growth rates did not show significantly different values between treatments. Therefore, Al content found in water sources in Colombia, despite being in the ranges reported as toxic for some aquatic plants, did not significantly affect the growth of E. crassipes due to its phenotypic plasticity and anthropic alteration of water sources but rather favor its growth. Key words: Aquatic weed, evapotranspiration, growth, invasive plant, stress, toxicity.