Author : Thawil Bua-ngam

Summary : Experiments were conducted to study the life cycle of water lettuce (Pistia stratiotes L.) as affected by pH and nutrition, the competing ability of this weed with rice and the other lowland weed species, its transpiration rate and the stage sensitive to herbicide action. Pistia seeds showed some degree of dormancy. They were also found germinate underwater, indicating a special mechanism that does not require oxygen or that needs very little amount of oxygen. Offshoot production was found very rapid. Starting from one plant at 2-leaf stage, 130 offshoots were counted within 2 months. Life cycle of Pistia either derived from sexual or asexual reproduction is completed within 5 to 6 months.