Effects Of Saline-alkali Stress On Physiological Indexes Of Alfalfa And Evaluation Of Salt Tolerance

Soil salinization has become one of the world's most serious ecological problems.According to the relevant statistics,the global salinization of the land area is about 9.5 billion hectare,which has seriously affected the sustainable development of agriculture and animal husbandry.The western part of Jilin Province locates in the southwest of the soda saline-alkali distribution area “the southwest of the Songnen Plain”.In recent years,due to the unrestrained the grasslands cultivation and undermined the environment for temporary economic benefits,the saline-alkali land area had expanded fastly in the western region of Jilin Province.In that content,it is particularly important to focus on the improvement of the ecological environment by improving and using saline-alkali soils to maintain economic benefits.Alfalfa is a kind of forage grass with good tolerance to salt and alkali,and it has significant difference in salt and alkali tolerance.It can not only improve the saline-alkali soil and improve their utilization,but also for the agriculture and animal husbandry to provide more high-quality protein feedings,therefore the development of animal husbandry will be promoted and high ecological and economic value will be brought.In this study,sandy soils and saline soils with different proportions were used as natural substrate,based on the saline-alkali constituents of their natural types,the physiological and ecological parameters of different alfalfa varieties at different growth stages were identified.By measuring the growth status and physiological and ecological parameters of alfalfa in different periods,the tolerance to the suabstrate saline-alkline stresses were evaluated,thus the alfalfa aultivars,which suitable distributed in the western Jilin Province,with high saline-alkline tolerant capacity will be identified.Meanwhile,the soil composition conditions of alfalfa cultivation were explored by the field experiment and pot experiment to test the best soil compoment for alfalfa planting.The results are as follows:(1)The alfalfa tolerance of different alfalfa varieties was different,accoroding to the germination experiment,nineteen alfalfa varieties could be divided into the following four groups by subordinate function analysis and cluster analysis:(I)Strong salt-alkline tolerance varieties: Magna Graze II,Optimus,Xinjiang Daye,Xinmu 1,Caoyuan 3;(II)moderate salin-alkline tolerance to salt and alkali varieties: Xinmu 4,DSB 37 CR,Longmu 801,Zhongmu 1,Longmu 806,AC Caribou,Gongnong 1,Longmu 803,Dongmu 1,Zhaodong,Gongnong 2;(III)Weak saline-tolerant varieties: Dongmu 3 and Magna Graze CR;(IV)Saline-alkline sensitive varieties: Gongnong 5.(2)In the experiment,the saline-alkline tolerance of difference varities performendsimilar to that of the during the germinated period;the soil suitable for alfalfa growth is treatment 4(T4),whereas sand / saline soil ratio was 2:3(pH 8.6,conductivity 175.0 ?s / cm).(3)The physical and chemical properties of soils in 20-40 cm soil layer had a significant effect on the yield of alfalfa(Dongmu 1)grown in different salinity soils.The soil physical and chemical properties of highest yield location were similar to those of alfalfa cultivated in saline soil.(4)With the increase of salt and alkali stress,the content of proline in plants was significantly increased,and the content of proline in alfalfa cultivars with strong salinity tolerance was significantly higher than that of low salt tolerance cultivars.The results showed that proline had an important effect on regulating alfalfa to adapting to salt and alkali stress.However,due to the moderate salt and alkali can promote the growth of alfalfa,therefore the proline content appeared declined in a certain salt stress treatment.With the increase of salt and alkali stress,the content of soluble sugar increased,and the content of soluble sugar in salt-tolerant cultivars was also higher,which indicated that alfalfa with high salinity resistance could also improve the soluble sugar content to enhance their tolerance to salt tolerance.Under the saline-alkline stress,alfalfa could accumulate the K+and block the absorption of Na+,and thus maintain a certain Na+/K+.Na+/ K+ increased with the saline-alkline stresses,but the high resistance to salt and alkali cultivar could maintain a lower Na+ / K+.