Evaluation of Germinability in Rice Germplasm Under Low Temperature and Anaerobic Conditions.

Direct-seeding cultivation of rice is increasing in Asia instead of transplanting system, because of its lower cost and operational simplicity. Low-temperature germinability (LTG) and anaerobic germinability (AG) are important characters for breeding of varieties for wide-spread adoption of direct-seeding cultivation in rice. Water temperature during sowing season is frequently below 15 °C, resulting in poor seedling establishment and less crop yield in temperate or high altitude areas. This study was performed to evaluate LTG and AG of rice germplasm and identify accessions with strong germinability on both low-temperature and anaerobic conditions. A total of 180 rice germpalsm comprising of diverse rice subpopulations were evaluated for germination vigor and germination rate. While aus germplasm showed the highest germination vigor and rate for LTG, the highest coleoptile length and germination rate was observed in temperate japonica and tropical japonica germplasm for AG, respectively. Indica and aus groups showed lower germination vigor and rate than japonica group for AG. For development of molecular markers for evaluation of rice germplasm with enhanced LTG and AG, previously reported QTLs for LTG and AG were integrated to identify the target region. A total of 96 candidate SNP markers were selected from all 12 rice chromosomes. Among these, 28 markers were identified in chromosome 7 where four overlapping regions between LTG and AG QTLs were detected. Candidate markers were applied in 192 accessions which have evaluated for LTG and AG and progress on marker development will be presented.