Inheritance of rice cold tolerance at the germination stage

RESUMO

Cold tolerance during germination is important for ensuring fast and uniform establishment of a rice crop early in the season. However, evaluation of this trait under field conditions is limited by environmental variation, which makes it difficult to identify genetically superior lines. Evaluation of cold tolerance under controlled temperature conditions may be performed by assessing percentage of reduction in coleoptile length and coleoptile growth. Our study determined the inheritance and heritability of cold tolerance at the germination stage in crosses between six rice genotypes. Diallel analysis showed that while both additive and non-additive gene action were involved, the non-additive action was relatively more important for percentage of reduction in coleoptile length and coleoptile growth. Our data shows that genotype Quilla 66304 would be the best parent in crosses aimed at increasing cold tolerance at the germination stage in rice due to its high general combining ability for both percentage of reduction in coleoptile length and coleoptile growth. Generation mean analysis was also performed for coleoptile growth in six cold-sensitive x cold-tolerant crosses and proved that non-additive effects were due to dominance and epistatic interactions. Though broad sense heritability values were high, the relative importance of the non-additive effects suggests that selection should be applied in advanced generations of the breeding program.