Purpose To clarity the specific adaptive mechanisms and stress tolerance thresholds of Potentilla anserina L. seedlings under different types of saline-alkali stress in alpine regions, and to provide a theoretical basis for ecological cultivation in saline-alkali soils of the Qinghai-Tibet Plateau.
Methods Taking ‘Qinghai Juema No. 6’ as the material, hydroponic culture method was used to three stress types (NaCl, NaHCO3 and NaCl+NaHCO3 mixed salt-alkali) and four concentration gradients (50, 100, 150, and 200 mmol/L). After 21 days of treatment, growth indicators, photosynthetic pigment contents, antioxidant enzyme activities, osmotic adjustment substances and membrane lipid peroxidation product levels were systematically determined. The membership function method was used to comprehensively evaluate the stress tolerance based on 16 indicators.
Results The response of P. anserina to saline-alkali stress exhibited dual characteristics of “type specificity and concentration dependence”, with the stress tolerance ranking as NaCl>mixed saline-alkali>NaHCO3. 50 mmol/L NaCl significantly promoted the growth of P. anserina, increasing its plant height and chlorophyll a content by 63.3% and 23.2% respectively compared to the control, while also enhancing the activities of superoxide dismutase and catalase significantly. 50 mmol/L was the safe concentration threshold for P. anserina seedlings to tolerate salt-alkali soils, and their comprehensive stress tolerance significantly decreased when the concentration exceeded 100 mmol/L. Membership function analysis revealed that 50 mmol/L NaCl could promote the growth of P. anserina, and the comprehensive salt-alkali tolerance of plants was the weakest under 200 mmol/L NaHCO3 treatment.
Conclusion P. anserina exhibits significantly higher tolerance to neutral than to alkaline salt, and low-concentration NaCl stress enhances growth by activating photosynthetic and antioxidant systems.
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