Since rice production in the LW zone can be increased only by increasing the yield per unit area, emphasis should be placed on the identification of varieties to replace indigenous rice varieties. The poor dissemination of high-yielding varieties in the LW zone of Sri Lanka is mainly due to the failure of the new varieties to show field stability over a wide range of soil and climatic conditions. In the LW zone, submergence and iron toxicity are the most serious constraints. It is, therefore, essential to incorporate characters tolerant to these constraints into new varieties. And the screening and selection techniques presented here promise to be useful in breeding and selecting varieties tolerant to these constraints.
　The production potential of the varieties screened was evaluated in cultivation under farmer management, and varieties with desirable agronomic traits for low management conditions were selected. BW 272-6B and BW 267-3 were identified as the most suitable replacements for indigenous rice varieties in Kalutara and Galle districts. These two varieties exhibited a wide adaptability to many locations and proved to be similar to indigenous varieties in their adaptability and low management requirements.