Indução de mutação em sementes de arroz (Oryza sativa L.) e seleção de possíveis mutantes M2 para a dormência e tolerância ao frio na germinação

Abstract

Cultivated in more than 150 million hectares, rice (Oryza sativa L.) is one of the most important crops around the world. In 2005 approximately 600 millions tons were harvested. Moreover, the rice grain is the basic food for at least four billion people worldwide. Rice breeding programs are looking for the development of new varieties with higher productivity, nutritionally traits and environment stresses tolerance. Initially using the existing variability to create new recombination, through artificial hybridizations, and, later, inducing mutations. The generation of a mutant population looking for selects putative mutants for dormancy and tolerance to low temperature during germination, may be contribute to know mechanisms involved in these traits, moreover in the future, it may be possible to develop new and better genotypes. The goal of this work was to generate a mutant population of rice from the BRS 7 Taim cultivar and to identify putative mutants for dormancy and germination under low temperature. Ten thousand seeds of the BRS 7 Taim cultivar were submitted to 250 Gy. The M1 seeds were cultivated in field to produce M2 seeds. Thirty M2 seed populations were harvested and evaluated. The mutation induction allowed the generation of a mutant bank with differentiated performance for dormancy and tolerance to low temperature in the germination. The M2 24 seed population seems to be the better one to study the dormancy trait. The M2 mutant populations showed different performance in the germination test under 13°C, however, it was no possible to select a putative M2 population based on the coleoptile length.