Study On Salt And Alkaline Tolerance Of Four Native Plants In Xinjiang During Germination And Seedling Stage

In recent years,grassland degradation in Xinjiang has been serious,and the salinization area has increased year by year.It is particularly important to use saline alkali tolerant germplasm resources for no tillage and supplementary sowing to restore degraded grassland,and understanding the saline alkali tolerance of native plant germplasm resources is the basis of this work.In this study,Kalidium foliatum,Kalidium caspicum,Halostachys caspica and Psathyrostachys juncea were used as experimental materials.During germination,four kinds of sodium salts were used as stress factors,neutral salt（Na Cl,Na₂SO₄）was set with7 salt concentration gradients of 0 mmol·L^-1（CK）、100 mmol·L^-1、200 mmol·L^-1、300 mmol·L^-1、400mmol·L^-1、500 mmol·L^-1、600 mmol·L^-1,alkaline salt（Na HCO₃,Na₂CO₃）was set with 7 salt concentration gradients of 0 mmol·L^-1（CK）、50 mmol·L^-1、100 mmol·L^-1、150 mmol·L^-1、200 mmol·L^-1、250mmol·L^-1、300 mmol·L^-1,and four plant seeds were stressed.At seedling stage,soil extract was used and three salt alkali treatments of light,moderate and high were set for pot experiment,through the determination of germination indexes such as germination rate and germination potential,as well as physiological indexes such as malondialdehyde and soluble sugar content to explore the effects of different saline alkali stress on the germination characteristics and Seedling Physiology of four plants.The results showed that:（1）Under the stress of four salt types,the germination rate,germination potential,germination index and vitality index of Kalidium caspicum and Psathyrostachys juncea decreased with the increase of salt concentration.Especially,under the treatment of neutral salt≥400 mmol·L^-1 and alkaline salt>150 mmol·L^-1,the germination rate of Kalidium caspicum is less than 10%or almost.Kalidium foliatum and Halostachys caspica had low salt promotion under 100 mmol·L^-1 neutral salt and 50 mmol·L^-1 alkaline salt.Under the same conditions,the growth of radicle or germ of four plants also had low salt promotion,and the inhibitory effect of salt stress on Radicle was greater than that of germ.Under different salt stress,the salt tolerance thresholds of different indexes of the four plants were different.Among them,Halostachys caspica had the highest salt tolerance threshold and limit value under four kinds of salt stress,followed by Kalidium foliatum,Kalidium caspicum and Psathyrostachys juncea.The responses of the four plants to different salts were different.It was generally considered that the inhibitory effect of alkaline salt on seed germination was greater than that of neutral salt.（2）With the increase of saline alkali concentration,the relative conductivity of the four plants increased by 41.03%～278.41%,the content of malondialdehyde increased by 27.20%～155.61%,the relative water content of leaves decreased by 3.62%～31.52%,the content of proline increased by 89.71%～823.00%,the content of soluble sugar increased by 12.92%～393.44%,the content of Na⁺increased by 142.12%～377.42%,and the content of K⁺decreased by 60.77%～75.10%;The comprehensive analysis of fuzzy mathematics membership function shows that under different concentrations of saline alkali stress,the membership function values of the four plants are Halostachys caspica>Kalidium foliatum>Kalidium caspicum>Psathyrostachys juncea.Combined with the appearance observation,it is considered that Psathyrostachys juncea are suitable for supplementary sowing in mild saline alkali,Kalidium caspicum can adapt to moderate saline alkali,and Kalidium foliatum and Halostachys caspica can be used in severe saline alkali.