Development of high yielding two-line hybrid rice in Thailand.

Thailand is a major producer and exporter of rice. However, the yield per hectare of Thai rice is lower compared with other Southeast Asian countries. We hypothesized that higher-yielding hybrids of Thai varieties could be generated using the temperature-sensitive genic male-sterility (TGMS) two-line hybrid technique. In this study, we evaluated inter-station yield of 14 hybrids generated from two IRRI TGMS rice lines crossed with 13 Thai elite lines/cultivars and planted at different locations in Thailand for two years. One hybrid (Hyb1) showed at least 10% greater yield than the mean of four high-yielding inbred reference cultivars for all tested years and locations. Eight functional markers controlling agronomically important traits were used to genotype the parents and Hyb1. Positive alleles associated with the important traits were identified among the parents, and four markers were found to be polymorphic. Because contaminants in hybrid seed lots can greatly decrease yield, two of the polymorphic markers were used to assess seed purity of Hyb1. No contaminants were detected, i.e. indicating 100% seed purity for the hybrid. The results obtained here will be useful for developing high yielding rice cultivars in Thailand. [ABSTRACT FROM AUTHOR]