Severe
water stress is responsible for reducing plant growth and reproduction. This study aimed to evaluate the physiological and biochemical mechanisms associated with the tolerance of two genotipes of bahiagrass (Paspalum notatum Flügge) with different ploidy level to water deficit and flooding at the reproductive stage. Photosynthetic performance of diploid and
tetraploid plants was not affected by flooding. In contrast, the water deficit decreased stomatal conductance, increased leaf temperature, and resulted in a decrease in the assimilation rate of the two genotypes. Despite the greater activities of
antioxidant enzymes, flooded roots accumulated
hydrogen peroxide and
malondialdehyde. Roots of plants exposed to water deficit maintained an accumulation of biomass similar to that of control plants; however, with higher levels of total
phenol content, total soluble
sugars and
proline. Diploid plants subjected to flooding had more inflorescences, however, the drought reduced the total number of filled florets per plant. Less
starch degradation allows the maintenance and recovery of biomass in the
tetraploid genotype, which allows it to maintain its reproductive performance even under drought conditions. Overall, the synthesis of osmoprotectants and activation of
antioxidant machinery are important strategies in the tolerance of bahiagrass to
water stress at the reproductive stage.