Physiological and biochemical performance of hydric stress-produced rice seeds

Antioxidant complex enzymes have a significant role in cellular homeostasis control in plants, and they inhibit the toxic action of reactive oxygen species when they are in excess. There are many antioxidant enzymes executing this role; among these, superoxide dismutase, catalase, and ascorbate peroxidase are reported as the most studied in this process, as they prevent free radicals from becoming more reactive and toxic to cells. Thus, this research was conducted to evaluate antioxidant enzyme expression in response to hydric stress at the reproductive stage in upland rice genotypes. Three genotypes from the upland rice breeding program on agreement between UFLA, EPAMIG, and EMBRAPA, CMG2093, CMG2172, and BRSMG Relâmpago, were used as controls. Genotypes were grown under field conditions with supplementary irrigation during the whole crop cycle, and hydric stress was induced in the reproductive phase before panicle emission. Seedlings were used in enzyme analyses from the emergence test and IVE on substrate (soil + sand at a 2:1 rate) at 70% and 10% field capacity. Significant differences were observed among genotypes for vigor tests. In biochemical tests, the CMG2093 genotype had lower damage on hydric deficit, with the best performance under hydric restriction conditions, being considered tolerant for this stress type.