Evapotranspiration from Eichhornia crassipes, Pistia stratiotes, Salvinia herzogii and Azolla caroliniana during summer in Argentina

Water loss due to evapotranspiration (E) was evaluated for four types of aquatic floating plants. Several treatments were carried out on waterhyacinth (Eichhornia crassipes (Mart.) Solms.); water lettuce (Pistia stratiotes L.); Salvinia (Salvinia herzogii de la Sota) and water fern (Azolla caroliniana Willd.), all of which were compared to free water. The evapotranspiration of water lettuce (84,000 1/ha/d), Salvinia (87,000 1/ha/d) and water fern (71,000 1/ha/d) did not show significant differences with evaporation (E sub(o)). The E of waterhyacinth was 150% higher than the E of the other species. The rate E/E sub(o) was 2.67 for waterhyacinth and close to one for the other aquatic plants.