Effects Of Salt Stress On Physiological And Biochemical Properties Of Two Spring Wheat Varieties In Northwest China During Germination

Soil salinization is a threat to the survival of human beings in the world.Seed germination is the initial stage of plant growth and development.Under the condition of salt stress,the comprehensive ability of the seeds to absorb water and swell and sprout roots,which can reflects the degree of tolerance to salt stress.Plants have evolved a series of adaptive mechanisms in the long-term effects of saline environment,including the regulation of related physiological processes.This mechanism can protect itself from the damage caused by salt stress.It is very significant to study the response of wheat seed germination stage to salt stress,and to explore the effect of salt stress on the physiological characteristics of wheat seeds.It can provide the theoretical basis for the breeding of salt tolerant varieties of wheat seeds and the methods of seed germination.In this study,the Spring Wheat Variety "Longchun 27" and "Longchun 30" were used as materials.The salt resistance of two wheat varieties was studied,and the changes of physiological indexes in response to salt stress were studied in the two groups.The main results of this study are as follows:1.The germination rate of two varieties of wheat seeds was not affected under low salt concentration(<25 mmol·L-1).When the salt concentration was greater than 50 mmol·L-1,the germination rate of the two varieties decreased with the increase of salt concentration.The germination potential was more sensitive to salt stress than germination rate,The germination potential of two varieties of wheat seeds was significantly affected at low concentration(<25 mmol·L-1).Under the same concentration of salt stress,the germination rate and germination potential of Longchun 30 were slightly higher than that of Longchun 27.2.The content of soluble protein and proline increased significantly with the increase of salt concentration,while the content of soluble sugar decreased with the increase of salt concentration.Under the same salt concentration stress,the soluble protein content of Longchun 27 was slightly higher than that of Longchun30.While in the same condition,the content of soluble sugar in Longchun 30 was higher than that of Longchun 27.3.Among the two varieties of wheat seeds,the activities of three related enzymes(OAT,PDH,P5CS)of the proline metabolism were inhibited by high concentrations of salt stress.Under the condition of salt concentration greater than 50 mmol·L-1,the activity of the three enzymes was significantly lower than that of the control group.The activity of P5 CS in two wheat varieties was close,and under the same salt concentration stress,the activities of OAT and PDH in the seeds of Longchun 30 were slightly higher than those of Longchun27.Under the same salt concentration stress,the inhibitory effect of salt stress on PDH's activity was more significant than that on OAT and P5CS's activity.4.The activities of antioxidant enzymes(CAT,POD,SOD,APX,GR)in the two wheat varieties were sensitive to salt stress.The higher the salt concentration,the lower the activities of these enzymes.In addition to APX and GR,the activities of the other three enzymes was significantly lower than those of the control group under the salt stress condition of 25 mmol·L-1,while the APX and GR's activities of the two varieties of wheat seeds in salt concentration is greater than 50 mmol·L-1 decreased significantly than those in the control group.Under the same concentration of salt stress,CAT's activity and GR's activity in Longchun 27 seeds are slightly higher,while the activities of APX and POD in Longchun 30 seeds are slightly higher.The activity of SOD is very close in the two varieties of seeds.5.Amylase's(alpha-AMS,beta-AMS)activities in the two varieties of wheat seeds decreased with the increase of salt concentration.High salt concentration(>50 mmol·L-1)stress significantly inhibited the activities of ?-AMS and ?-AMS.Under the condition of 200 mmol·L-1,the activity of ?-AMS in the seeds of Longchun 27 wheat and Longchun 30 wheat was decreased by more than 46.73% and about 40.69%,respectively,compared with those in the control group;The activities of ?-AMS was decreased by 70.32% and 69.99%,respectively,compared with those in the control group.The above results show that The higher the salt concentration,the more obvious the inhibition of the germination of the two wheat seeds.At the same concentration of stress,Longchun 30's germination effect is slightly better than Longchun No.27.Salt stress had more obvious effect on germination rate;At the germination stage,soluble proteins and proline play an important role in the osmotic regulation of wheat seeds.The main reason for the accumulation of proline is that under the same salt concentration stress,the inhibitory effect of salt stress on PDH's activity was more significant than that on OAT and P5CS's activity;Seed germination speed is more sensitive to salt stress environment,because most antioxidant enzymes(CAT,POD,SOD)activities are greatly inhibited under low salt stress,Therefore,the ability of seeds to remove their ROS has been weakened,resulting in slower metabolic efficiency;Salt stress significantly inhibited amylase's activity in wheat seeds;50 mmol L-1 was the threshold for the germination of these two wheat seeds to be significantly inhibited by salt stress.