CARACTERIZACIÓN DE GERMOPLASMA DE ARROZ PARA TOLERANCIA A FRÍO EN LA ETAPA DE GERMINACIÓN (Rice germplasm characterization for cold tolerance in the germination stage)

Because low temperature is a constraint in Chilean rice (Oryza sativa L.) production, part of rice germplasm was characterized for cold tolerance in the secondary stages of germination, Z00 and Z07 of Zadoks scale. The study was done in the laboratories of Quilamapu Rice Research Center of the National Agriculture Research Institute (INIA), Chillán, Chile. In the Z00 stage, normal plants were evaluated in 162 genotypes in 9 experimental units in a complete randomized design with three replicates, exposed to 13ºC during 35 days. In the stage Z07, percentage of living plants were evaluated in 187 cultivars and advanced lines divided in 9 experimental units, in a complete randomized design with three replicates and two factors: genotypes and period of exposition to low temperatures (5 and 15 days). Low temperature affected rice germination, the genotypes presented a great variability. There were 14 cultivars and advanced lines tolerant in Z00 stage and 76 lines in Z07 stage. Only 8 genotypes presented cold tolerance in both stages, indicating that different systems of genetic control may be involved. The use of 5 days of exposition to low temperature in the Z07 stage was adequate for the evaluation in laboratory conditions