Eichhornia crassipes (Mart) Solms in wastewater treatment: Reducing low-temperature stress

Abstract

Studies were carried out from July 1988 to August 1989 to assess the growth and winter survival of water hyacinth, Eichhornia crassipes (Mart.) Solms, in treatment of secondary domestic wastewater in Tucson, Arizona. Percent of surviving overwintered plants for the following frost protection treatments from November 1988 to March 1989 was: 25 (control), 48 (plastic tarps), 70 (sprinklers), 34 (fog) and 76 (greenhouse). Both control plants and protected plants had longer roots at the effluent end of the ponds than the influent ends during winter months. Greenhouse-protected plants had greater root and entire plant lengths, and greater fresh and dry weights. Dry weight per unit area (kg m⁻²) was higher for greenhouse plants though all protected plants showed decline in dry weight per unit area with temperatures below 10 C. Qualitative observations indicated that protected plants showed less chlorosis and necrosis from low temperatures than control plants, however, plants in all frost protected treatments experienced low temperature stress. Aphids were seen in some of the ponds throughout the study and contributed to severe lamina and petiole damage.