Evaluation of Rice Genetic Resources for Rice Breeding Utilization

Abstract

The National Rice Seed Storage Laboratory for Genetic Resources (NRSSL) was established to collect all known traditional varieties and wild species existing in Thailand. As we rice breeders need a wide range of genetic materials to broaden the genetic base for rice variety improvement. Characterization and germplasm evaluation are essential for utilization of rice genetic diversity. This research used information from 15,524 rice accessions evaluated over the last ten years. Some rice accessions showed particular traits
that might be useful for ongoing research and utilization. For example, 65 accessions display early-flowering insensitive rice, 792 accessions have short stature (< 100 cm), 1,172 accessions have large panicle size (> 30 cm), 20 accessions have high panicle number (> 25 panicles/hill), and 69 accessions have long leaf length (> 80 cm). Some grain physical characteristics were evaluated such as grain size and results show that paddy grain size ranges from 0.84-6.39 mm width, with 3.09-12.0 mm length, and 100 seed weight range of 1.19-5.67 g. The major grain chemical qualities such as amylose content was evaluated and revealed that 598 and 987 accessions have low (11-20 percent) and intermediate (21-25 percent) amylose contents, respectively. We also found 176 accessions of aromatic rice. Evaluation of 100 rice accessions against disease and insect resistance were conducted and found there were 19, 49, 1, 34 and 8 accessions resistant to bacterial blight, grassy stunt, ragged stunt, leaf blast and panicle blast diseases, respectively. For insect resistance, the results showed 7, 2, 11 and 42 accessions resistant to brown planthopper, whitebacked planthopper, rice gall midge and stem borer, respectively.