Effects Of Salicylic Acid On Morphology And Physiological Characteristics Of Saponaria Officinalis Under NaCl Stress

Saponaria officinalis has good ornamental effect and high medicinal value,so it has a broad market prospect and utilization value.Salinization of soil is one of the reasons that restrict its popularization and application.It was found that salicylic acid can improve the salt-tolerance of plants.In order to explore whether salicylic acid can become a feasible method to improve the salt-tolerance of Saponaria officinalis.In this experiment,Saponaria officinalis were used as plant materials,and salicylic acid of different concentrations(0.2,0.4,0.6,0.8,1.0 mmol·L-1)was applied to Saponaria officinalis under NaCl stress(0.2%,0.4%,0.6%),to explore the influence of salicylic acid on the morphology and physiological characteristics of Saponaria officinalis under NaCl stress.1.Salicylic acid increased the growth of Saponaria officinalis height under 0.2%and 0.4%NaCl stress compared with the control,but had no significant effect on the growth of Saponaria officinalis height under 0.6%NaCl stress.The effect of 0.6 mmol·L-1 salicylic acid on the growth of plant height of Saponaria officinalis was the most significant.After spraying 0.6 mmol·L-1 salicylic acid,the growth of plant height of Saponaria officinalis treated with 0.2%and 0.4%NaCl was significantly higher than that of the control at 20～25 days,128.26%and 93.27%higher than that of the control,respectively.Salicylic acid had no significant effect on the growth of leaf length and width.It indicated that salicylic acid had no significant effect on the morphology of Saponaria officinalis under NaCl stress.2.Salicylic acid made the relative conductivity and malondialdehyde content of Saponaria officinalis under NaCl stress lower than the control.Salicylic acid also made the soluble sugar content,soluble protein content and free proline content of Saponaria officinalis higher than the control.Compared with the control,the cell membrane permeability of Saponaria officinalis treated with salicylic acid decreased significantly.The relative conductivity of Saponaria officinalis treated with 0.4%NaCl was reduced by 35.19%and the content of malondialdehyde was reduced by 22.01%when the salicylic acid of 0.6 mmol·L-1 was used for 30 days.Salicylic acid increased the content of soluble sugar,soluble protein and proline in Saponaria officinalis.Salicylic acid at 0.6 mmol·L-1 increased the soluble sugar content by about 15%and the soluble protein and proline content by about 20%.These results suggest that salicylic acid can alleviate the damage of NaCl stress on cell membrane and improve salt tolerance by promoting osmotic regulation of Saponaria officinalis.3.Salicylic acid maed the activity of defense enzymes in Saponaria officinalis higher than the control.And enhanced the ability to resist salt stress.The salicylic acid of 0.6 mmol·L-1 increased the enzyme activity of Saponaria officinalis by the most,increased the activity of SOD,POD,CAT and PPO by about 30%,increased the APX by about 15%,and increased the PAL activity by more than one time in the later stage of treatment.The results indicated that salicylic acid could enhance the activity of the defense enzymes of Saponaria officinalis,thus promoting the ability of Saponaria officinalis to remove reactive oxygen species and enhancing the ability of Saponaria officinalis to resist salt.4.Salicylic acid made the chlorophyll content and photosynthetic capacity of Saponaria officinalis higher than the control.The net photosynthetic rate,transpiration rate and stomatal conductance of Saponaria officinalis treated with salicylic acid were higher than those of the control.However,the effect of salicylic acid on intercellular CO2 concentration was more complex under 0.2%NaCl treatment,but increased under 0.4%and 0.6%NaCl treatment.Salicylic acid at 0.6 mmol·L-1 had the strongest effect on photosynthesis,and increased net photosynthetic rate by about 15%.These results suggest that salicylic acid can enhance the photosynthetic capacityof Saponaria officinalis under NaCl stress,help to stabilize the normal physiological metabolism of Saponaria officinalis,and improve the resistance of Saponaria officinalis to NaCl stress.