Author : Soekisman Tjitrosemito

Summary : Photosynthetic rate of waterhyacinth plants was measured with URAS infra red gas analyzer at a constant CO2 concentration of 400 ppm, 25 degree celsius and 70 percent relative humidity. The photosynthetic rate varied from 7 to 36 klux; CO2 compensation concentration was 60 ppm. Pot experiments were carried out using 0.25 strength Hoagland's solution to investigate the photosynthate distribution using labelled 14CO2 also using various nitrogen concentrations (1-9 ppm), various phosphorus concentration (0.1-0.9 ppm), various potassium concentrations (0.5 ppm), various pH values (4-8), and various light intensities to investigate the accumulation of dry matter, production of stolon and mean relative growth rate of waterhyacinth. Photosynthate was distributed to growing points with highest percentage to stolon; dry matter accumulation, stolon number and mean relative growth rate were increased by increase in nitrogen, phosphorus, and potassium concentrations, while pH did not affect them.