Physiological Response Of Tamarix Chinensis Lour.Cultivar ‘Lucheng No.1’ To Salt Stress

A according to statistics,the total area of saline-alkali land in the world is aout 9.54 million km~2,of which the total area of saline-alkali land in my country is 991.3 thousand km~2,counting for about 10%of the country’s land area.Studying the mechanism of plant salt tolerance,digging,screening and making full use of salt-tolerant plants are effective ways to improve saline-alkali land by using biological measures.Tamarix chinensis Lour.is a desert halophyte.It has excellent characteristics such as resistance to salt and alkali,drought,wind and sand,and barrenness,and has a strong ability to adapt to extreme environments.Studying the physiological response of Tamarix chinensis Lour.to salt stress can provide a theoretical basis for its development and utilization.In this study,by observing the growth of the roots and leaves of the cutting seedlings of Tamarix chinensis Lour.variety‘Lucheng No.1’under different concentrations of NaCl,the relative electrical conductivity of the leaves of T.chinensis‘Lucheng No.1’at different concentrations and different periods was measured,and the salt damage index and the half-lethal concentration of NaCl were estimated.Treat T.chinensis‘Lucheng No.1’with a half-lethal concentration of NaCl solution,and determine the concentration of SOD,POD,CAT,MDA,proline,soluble protein,soluble sugar,Na~+and K~+in roots and leaves at different stages after treatment.Correlation analysis and principal component analysis were performed on these physiological indicators to clearly determine the physiological response of’T.chinensis‘Lucheng No.1’to salt stress.The main results are as follows:1、The effect of different NaCl concentration treatments on the growth of’T.chinensis‘Lucheng No.1’and the estimation of the half-lethal concentration:the leaves were fresher and the plant growth was better under the treatment of 100 mmol/L NaCl;the fresh weight and root length showed a continuous increase trend.The 200 and 300 mmol/L NaCl treatments of’T.chinensis‘Lucheng No.1’showed leaf wilting and were about to die by the 12 th day;the fresh weight and root length were reduced by 13%,11%and 20%,22%at these two concentrations,respectively.The 400 and 500 mmol/L salt-treated T.chinensis‘Lucheng No.1’died on the 8th day and the 4 th day,respectively.Experiments show that 100 mmol/L NaCl treatment has a certain promoting effect on T.chinensis‘Lucheng No.1’;200 and 300 mmol/L NaCl treatments have an inhibitory effect;400 and 500 mmol/L salt treatments have a strong inhibitory effect.The phenotype of T.chinensis‘Lucheng No.1’sylvestris treated with different concentrations of salt was calculated to obtain the salinity index and the half-lethal concentration of T.chinensis‘Lucheng No.1’was 314 mmol/L.Using the measured relative conductivity of the leaves to calculate the regression equation,the half-lethal concentrations are 306 mmol/L and324 mmol/L.Combining the two methods,the salt-tolerant half-lethal concentration range of T.chinensis‘Lucheng No.1’.is 306～324 mmol/L,and finally 300 mmol/L is taken as the half-lethal concentration of T.chinensis‘Lucheng No.1’.2、Physiological response of’T.chinensis‘Lucheng No.1’under the condition of half-lethal salt concentration treatment:Treat cutting seedlings of’T.chinensis‘Lucheng No.1’with300 mmol/L NaCl,and measure the physiological indexes of roots and leaves.The results show as follows.The SOD activity showed a slight increase and then a decrease.The root and leaf trends were roughly the same.POD activity first increased and then decreased,the activity in leaves was higher than that in roots.CAT activity first decreased in the root and then increased and then decreased,leaf activity first increased and then decreased.The relative conductivity of the leaves showed a continuous increase of single-peak change;the MDA content of roots and leaves increased first and then decreased,and the leaves were significantly higher than the roots.The content of proline and soluble sugar first increased and then decreased,the soluble protein content first decreased,then increased and then decreased.The concentration of Na~+keeps increasing,the concentration of K~+keeps dropping,and the ratio of Na~+/K~+keeps increasing.It shows that its own antioxidant enzyme system,cytoplasmic membrane permeability,osmotic regulators,etc.can quickly respond to the damage caused by salt stress when T.chinensis‘Lucheng No.1’is exposed to salt stress.3、Principal component analysis of the physiological indicators of roots and leaves at the half-lethal concentration found that the cumulative contribution rate of the first two principal components in the root is 96%.The larger eigenvector value of the first principal component is the proline content and CAT activity;and the larger of the second principal component is Soluble sugar content and Na~+/K~+ratio.The cumulative contribution rate of the first two principal components in leaves reached 93.7%.The larger eigenvector values of the first principal component were soluble protein content and proline content;The big ones are MDA activity and soluble sugar content.Therefore,salt stress has a greater impact on the physiological indicators of T.chinensis‘Lucheng No.1’roots:proline content,CAT activity,soluble sugar content and Na~+/K~+ratio;Therefore,salt stress has a greater impact on the physiological indicators of’T.chinensis‘Lucheng No.1’roots are the proline content,CAT activity,soluble sugar content and Na~+/K~+ratio,and the greater impact on leaf physiological indicators is the soluble protein content,Proline content,MDA activity and soluble sugar content.The above physiological indicators are the main indicators of the physiological response of’T.chinensis‘Lucheng No.1’to salt stress.