Seleção e caracterização de mutantes de arroz para tolerância ao déficit hídrico e produtividade

Abstract

Rice (Oryza sativa L.) is one of the most consumed cereals in the world. To meet the demand for food and consumer requirements, it is necessary to constantly search for new cultivars with great yield and capable of tolerating adverse conditions. One of the critical problems for this crop is stress due to water deficit, which affects world food security, especially in the context of global climate change. The development of new rice cultivars is a great challenge for breeders, and obtaining strategies to increase genetic variability has demanded the attention of several research groups. In this context, artificial mutations emerge as tools to help conventional methods of genetic improvement. Mutation induction is an important alternative method for creating genetic variability. Thus, the aim of this study was to characterize rice mutants in terms of water deficit tolerance and yield. For this, artificial mutations were induced in the cultivar BRS Pampeira through the use of gamma radiation at doses of 250 and 300 grays. The presence of genetic variability within the studied mutant population was observed, demonstrating the efficiency of the gamma radiation doses used. The activity of the enzymes of the antioxidant system varied among the mutants submitted to water deficit, as well as in the different periods of stress. This behavior suggests that the mutants have a distinct response to water deficit. The shortening of the flowering time was detected in five mutant lines, which have identical yield to the original cultivar. Although these genotypes are not water deficit tolerant at the reproductive stage, they can use the escape strategy to deal with drought, in addition to using less water during the harvest season. Finally, mutants with higher yield than the original cultivar were identified.