| At present,the problem of soil salinization is becoming more and more serious.The production of saline-alkali land makes it difficult to use a large area of soil,resulting in a significant reduction in the yield of various crops,which seriously limits the development of agricultural economy.Taraxacum mongolicum Hand-Mazz,a perennial herb of Compositae,is a plant with high economic benefits,and has high edible value and medicinal value.It has a wide distribution range,strong adaptability and stress resistance,and has a certain salt and alkali resistance.Therefore,this experiment adopts the method of pot experiment,with two different ecological types of Taraxacum mongolicum Hand-Mazz as the test material,using different kinds of salt solution to simulate salt stress（Na Cl）,alkali stress（Na2CO3）and salt-alkali mixed stress（Na Cl and Na2CO3）,by analyzing the three different types of salt stress in plant damage degree,osmotic adjustment,antioxidant capacity and quality,etc.,to study the effects on the growth and quality of Taraxacum mongolicum Hand-Mazz without harvest and harvest,and to provide theoretical basis for the cultivation of different ecological types of Taraxacum mongolicum Hand-Mazz in saline-alkali land.The test results are as follows:（1）Under salt stress,alkali stress and salt-alkali mixed stress,the damage degree of Taraxacum mongolicum Hand-Mazz plants increased gradually with the prolongation of stress time and the increase of stress concentration.Mild salt stress（Y1）,mild alkali stress（J1）and low alkali and low salt mixed stress（H1）had no significant effect on the survival rate of two different ecotypes of dandelion plants.Under severe salt stress（Y3）,severe alkali stress（J3）and mixed stress of medium alkali and medium salt（H4）,the damage index of plants was the highest,and the relative growth rate of leaves,root activity and plant survival rate were the lowest.（2）Mild salt stress,low alkali and low salt mixed stress and moderate alkali stress（J2）all increased the contents of soluble sugar,soluble protein,vitamin C,chlorogenic acid,flavonoids and saponins in Taraxacum mongolicum Hand-Mazz leaves.With the increase of stress concentration,the quality content of Taraxacum mongolicum Hand-Mazz reached the lowest under severe salt stress,severe alkali stress and medium alkali and salt mixed stress.（3）Under salt stress,alkali stress and salt-alkali mixed stress,the malondialdehyde（MDA）content,proline（Pro）content and cell membrane permeability of Taraxacum mongolicum Hand-Mazz leaves increased gradually with the prolongation of stress time and the increase of stress concentration,and reached the highest at 50 days after stress.At the same time,H3 treatment was significantly higher than H2 treatment in saline-alkali mixed stress.Peroxidase（POD）and superoxide dismutase（SOD）reached the highest at 30 days after stress.With the prolongation of stress time,POD activity and SOD activity decreased the most under severe salt stress,severe alkali stress and medium alkali and salt mixed stress at 50 days after stress.（4）Different ecotypes of Taraxacum mongolicum Hand-Mazz have different degrees of salt tolerance.The salt tolerance,alkali tolerance and salt tolerance of Taraxacum mongolicum Hand-Mazz in Baoding City,Hebei Province are generally better than those in Jiamusi City,Heilongjiang Province.At 50 days after stress,the damage index,MDA content and cell membrane permeability of Taraxacum mongolicum Hand-Mazz plants in Baoding City,Hebei Province were generally lower than those in Jiamusi City,Heilongjiang Province;the plant survival rate,leaf relative growth rate,root activity and chlorophyll content of the former were generally higher than those of the latter. |
