Lanthanum Mitigates Postharvest Flower Senescence in Hemerocallis fulva L. by Accentuating the Antioxidant Machinery

Lanthanum (La), a rare earth element, has garnered attention due to its diverse applications in agriculture, including its ability to orchestrate physiological parameters and crop yields. The current study investigates the impact of lanthanum in orchestrating postharvest oxidative stress and delaying senescence in detached scapes of Hemerocallis fulva. The flower scapes, featuring the most mature bud at the stage preceding anthesis by one day, were collected and categorized into four groups. Each group were treated with varying concentrations of Lanthanum chloride (LaCl3); as a source of La at 15, 30, 45 and 60 µM concentrations. An additional group was kept in distilled water designated as the control. Our findings showed that LaCl3 at 45 μM significantly delayed senescence in the scapes of H. fulva. La improved the stability of cell membranes, increased antioxidant enzyme activity and prevented the increase of hydrogen peroxide (H2O2) levels in the tepals, thus reducing the adverse effects of reactive oxygen species (ROS). Moreover, La maintained high levels of proteins, sugars and proline in the tepal tissues, while also inhibiting bacterial growth in the test solutions, indicating optimal uptake of the solution by the flowers.