Research On The Response Of Eucommia Ulmoides And Three Salt-tolerant Trees Under Saline-alkali Mix Stress And Their Saline-alkali Tolerance

Land salinization is a severe problem,it is a important way to recover the saline-akali land by growing saline-alkali tolerant plants,but the plants fit to scale using of improving saline-akali land and recovering plants,especially can tolerate severe salt and alkali are limited.Eucommia ulmoides is a precious rubber tree in our counrty,it not only has important medical value,but also own fine properties,such as drought resistance,something about the mechanism and capacity of saline-alkali resistance is unclear.Elaeagnus angustifolia,Tamarix chinensis and Haloxylon ammodendron are three salt-tolerant shrub species,a large number of studies have proved that they own strong salt-tolerant,exploration of alkali resistance is unclear,due to a lack of comprehensive contrast,the conclusion of their saline-alkali resistance is uncertain.Therefore,this study adopts the method of artificial saline-alkali stress simulation,selecting two neutral salt NaCl and Na2SO4,two alkaline salt Na2CO3 and NaHCO3,according to the gradually increased of salt concentrationin,successively set contrast,low saline-alkali,middle saline-alkali,high saline-alkali,severe saline-alkali treatment,base on the change of the growth and physiological indexes explore the response of Eucommia ulmoides,Elaeagnus angustifolia,Tamarix chinensis and Haloxylon ammodendron under saline-alkali stress,we can deeply realize the character and adaptive mechanism of saline-alkali tolerant plants,through the method of multidimensional space coordinates make a comprehensive evaluation about saline-alkali resistance of four species under saline-alkali stress,analysize the difference between them,it has positive meaning to reveal the saline-alkali tolerant commonness of most species and the characteristics of good varieties,provide theoretcal basis for filtrating recoverable planting materical in saline-alkali land.Main conclusions are follows:(1)Low saline-alkali(100mmol/l,pH8.32)treatment can promote the growth of Tamarix chinensis and Haloxylon ammodendron,when salinity gets to 200mmol/l,pH gets to 8.74 will have obvious inhibition on them;Eucommia ulmoides and Elaeagnus angustifolia are suppressed by saline-alkali stress,with the increase of stress intensity of inhibition degree deepening.Under severe saline-alkali(400mmol/l,pH9.55)treatment,Elaeagnus angustifolia,Tamarix chinensis and Haloxylon ammodendron suffer severe suppress,but still keep growing,and when salinity get to 200mmol/l,pH get to 8.74,growth of Eucommia ulmoides almost ground to a halt,and unable to survive.(2)When suppressed by saline-alkali stress,the root of four plants suffer the bigger harm than overground part.(3)When four species suffered a certain range of saline-alkali stress,they increased the soluble sugar content and proline content to alleviate the the osmotic stress from the high salt environment to itself,improved the moisture absorption capacity;Enhanced the activity of protective enzyme POD and CAT to reduce the peroxidating damage to membrane lipid under saline-alkali stress;As the stress intensity rised,total organic acids content of four species increased,maintain the pH of internal environment stability,improve their saline-alkali resistance.(4)The saline-alkali resistance of Eucommia ulmoides is weak,only can grow under the low saline-alkali(100mmol/l,pH8.32)treatment,Elaeagnus angustifolia cannot bear severe saline-alkali treatment,the saline-alkali resistance of Tamarix chinensis and Haloxylon ammodendron is stronger.Comprehensive compare of the saline-alkali resistance of four species,the result is:Tamarix chinensis>Haloxylon ammodendron>Elaeagnus angustifolia>Eucommia ulmoides.