With a view to establishing the inf

With a view to establishing the influence of dry and wet seasons on the productivity of Pistia stratiotes L., samples of the plant were collected and their numbers, the dry weights of root and shoot systems and per cent moisture were determined. The results (Table 2) indicate that in Zone A the number of plants decreased during the wet season and the dry weights also decreased correspondingly. In Zones B and C, the number of plants almost doubled in the wet season and the dry weights of root and shoot systems increased considerably. The decrease in the number of plants and their weights during the wet season in Zone A may be due to the washing away of nutrients into Zones B and' C. This is also reflected in the increase in the number of plants and their weights in Zones B and C.