Caracterização de famílias mutantes de arroz (Oryza sativa L.) irrigado para tolerância a toxidez direta ao excesso de ferro em hidroponia

Abstract

Rice (Oryza sativa L.) is the staple food for more than three billion people, being considered one of the most important crop cereals for human nutrition. One of the factors that can impair the crop yield under the flooded-irrigated system is iron toxicity. Some of its common symptoms include decreased length and dry mass of shoots and roots, brown spots on leaves and damage to chlorophyll. The initial development of rice is also affected under this stress. A technique used to increase genetic variability for breeding purposes is the artificial induction of mutations. Given the above, the aim of the present work was to characterize a group of rice mutants for tolerance to iron toxicity at early development. The mutant families are in the M8 generation and were obtained from the BRS Querência cultivar, via treatment with EMS. These lines were evaluated under hydroponic condition, after exposure to iron stress of 400 mg L-1 for 14 days, for the variables shoot and root length, shoot and root dry mass, chlorophyll a and b index and leaf spots. Three mutant families, superior to BRS Querência for Fe tolerance for seven variables were identified, which represent promising tolerance sources for breeding programs. The analysis of principle components (PCA) and hierarchical clustering showed genetic variability for iron toxicity tolerance in the group of mutant families studied. The population is promising from the breeding point of view but also can serve as a reference for future studies for stress tolerance, and several molecular studies in rice.