Lanthanum nitrate improves phosphorus-use efficiency and tolerance to phosphorus-deficiency stress in Vigna angularis...

Here, we examined the effects of La³⁺ on growth, photosynthetic ability, and phosphorus-use efficiency (PUE) in various organs of adzuki bean (Vigna angularis) seedlings. La³⁺ substantially alleviated P-deficiency symptoms. Treatment of young seedlings with La³⁺ at 150 mg L^-1 effectively improved PUE in roots, stems, and leaves via the regulation of root elongation and activation of root physiological responses to P-deficiency, e.g., root activity and acid phosphatase (APase) activity. Root hydraulic conductivity (L_p) was also examined to elucidate the role of La³⁺ in the relationship between water and nutrition transport. We confirmed that La³⁺ increased the level of antioxidant protective enzymes, including superoxide dismutase (SOD) and peroxidase (POD), while it significantly decreased malondialdehyde (MDA) content. The use of La³⁺ to reduce photosynthesis damage under P-deficiency was examined. The negative effects of P-deficiency on net photosynthetic rate (P_n), transpiration rate (T_r), maximum photochemical efficiency (F_v/F_m), and chlorophyll content in leaves were alleviated by La³⁺ treatment. These results clarify the regulatory functions of La³⁺ in stress tolerance and P utilization in adzuki bean seedlings.