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 (Lp) 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 (Pn), transpiration rate (Tr), maximum photochemical efficiency (Fv/Fm), 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.
Keywords: Adzuki bean; Lanthanum nitrate; Phosphorus deficiency stress; Phosphorus use efficiency.