New rice-breeding methods for the rainfed lowlands of North and Northeast Thailand

摘要

The rainfed lowlands comprise a major rice ecosystem in Thailand, occupying about 5.7 million hectares of the country's total rice land of 9.2 million ha. Most of these lowlands are found in the north and northeast, and can be classified as shallow-favourable and shallow-drought-prone. Grain yield is generally low, partly because current cultivars have low potential grain yield and lack resistance to biotic and abiotic stresses. Attempts to develop rice cultivars for the rainfed lowlands by the current breeding program have been successful, with two cultivars being recently released. However, identifying lines for release took a long time and, while they performed well across targeted environments, their yield improvement has been minor. One outcome of the ACIAR project on "Plant-Breeding Strategies for Rainfed Lowland Rice in Northeast Thailand and Laos" was the identification of areas for potential improvement in the current breeding program. A new breeding program was begun in the 2000 wet season. Its two major objectives were to improve resistance in existing cultivars, and to increase potential grain yield in new cultivars. The selection scheme was changed to emphasize inter-station selection and on-farm trials. Marker-assisted selection for drought and blast resistance is being developed and will be incorporated into the new breeding program.