ABSTRACT
OBJECTIVE:To study the resistance effect of LaCl3 on different varieties of mint under saline-alkali stress with dif-ferent concentrations,and provide theoretical and experimental basis for its planting. METHODS:NaCl saline stress and NaHCO3 alkali stress with low,medium,high concentrations(25,50,100 mmol/L)were conducted for 4 kinds of mint [Mentha haploca-lyx Briq.,Mentha spicata Linn.,Monarda didyma L.,Mentha rotundifolia (Linn.)huds]. Growth indexes (survival rate,plant height,fresh weight and dry weight)were determined,and mint species with good resistance were screened. The effect mechanism of La3+ on growth indexes in saline-alkali stress with different concentrations,osmotic regulation indexes [soluble sugar(SS),solu-ble protein (SP), proline (Pro)], antioxidant activity indexes [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT)],the yield of volatile oil,and resistance were determined. RESULTS:After saline-alkali stress,M. didyma and M. rotundi-folia had low survival rate,which were not suitable for growth under given climatic conditions. For M. haplocalyx and M. spicata, saline-alkali stress with low concentration can significantly increase the growth indexes under no artificial intervention. La3+ can sig-nificantly increase the yield and CAT activity under no stress. Compared with non-spraying La3+group,the SOD,CAT,POD activi-ties of mint added La3+ under saline stress with low,medium,high concentrations,plant height and fresh weight under alkali stress with high concentration,SOD activity and SS content under alkali stress with medium,high concentrations,and POD activity un-der alkali stress with medium concentration were significantly increased. CONCLUSIONS:Spraying La3+ can significantly improve the growth of M. haplocalyx and M. spicata under alkalized soil with medium,high concentrations. Mentha haplocalyx Briq. is se-lected as the mint specy with the best saline-alkali resistance.