The Stress Of Neutral And Alkaline Salts On Solanum Nigrum L

Soil salinization has become a worldwide environmental problem which exerts more and more serious threat to plant growth.Therefore,it is of great significance to study the salt tolerance of plants from the perspective of physiological and biochemical and morphological aspects.In this study,seeds and seedlings of Solanum nigrum L.were treated with different concentrations of solution of 0(control),50,100,150,200 and 300 mmol·L-1 respectively.The solution is made from NaCl,Na2SO4,NaHCO3 and Na2CO3.The germination rate,germination potential and germination index of Solanum nigrum L.seed were studied under neutral salt and alkaline salt stress.Through the salt tolerance indices including growth,biomass,chlorophyll content,various antioxidant enzymes of Solanum nigrum L.and osmotic adjustment of material content analysis.Assess synthetically the salt tolerance.Below are key research findings.(1)With the increase of salt concentration,the germination rate,germination potential and germination index of Solanum nigrum L.seed decrease to a certain extent.When the concentration of salt was 0 ~ 30 mmol·L-1,the germination of seeds is promoted,but is inhibited at 45 ~ 75 mmol·L-1.The germination of seeds is severely inhibited at 15 mmol·L-1.For the concentration is 60 mmol·L-1,seeds will not germinate.(2)Under the influence of neutral salt and alkaline salt,Solanum nigrum L.seedlings are subjected to oxidative stress.With the increase of salt concentration,the content of malondialdehyde in leaves increases,and the activities of antioxidant enzymes(SOD,POD,CAT)are also increasing.Under the influence of neutral salt,the activity of antioxidant enzymes reach the maximum at the concentration of 100 ~ 150 mmol·L-1,and then begin to decrease.Under the influence of neutral salt stress,only the activity of POD increases,but the activity of SOD and CAT increase at first and then decrease.Under the influence of single salt,only the activity of CAT keeps falling,but the activity of the other two enzymes increase.MDA in Solanum nigrum L.seedlings accumulate under the influence of alkaline salt,and reach the highest at 300 mmol·L-1,compared with the neutral salt,the difference is significant.(3)Both Neutral salts and alkaline salts can produce osmotic stress on the seedlings of Solanum nigrum L.And with the increase of salt concentration,the water content in Solanum nigrum L.leaves decreases,but the content of osmotic adjustment substance(proline and soluble sugar)increases.Under the influence of alkaline salt,the content of proline and soluble sugar in the leaves of Solanum nigrum L.are more than that under the condition of neutral salt.(4)Both the influence of neutral salt and alkaline salt will inhibit the growth of Solanum nigrum L.seedlings,mainly showing in plant height,root length,biomass and the content of chlorophyll.The tolerance threshold of NaCl is 211.74 mmol·L-1,and the tolerance threshold of mixed stress of NaCl and Na2SO4 is 170.35 mmol·L-1,and the tolerance threshold of mixed salt stress is 128.51 mmol·L-1.Alkaline salt has a greater inhibitory effect on the growth of Solanum nigrum L.seedlings.