The Effects Of NaCl Stress On Seeds Germination Research And Physiochemical And Biochemical Properties Of Calystegia Soldanella Seedings

Currently, the coastal sand plants were reduced due to various reasons such as tourismdevelopment and other man-made causes so that the ability of sand-fixing for coastal sandwas weakened. Calystegia soldanella played an important role in coastal sand-fixing. so theresearch for Calystegia soldanella has great significance to protect coastal environment anddevelop medicinal plants. This paper mainly studied the effects of different concentrationsof NaCl stress on the Calystegia soldanella seed germination and seedlings, and analysedphysiological and biochemical characteristics. The main conclusions were as follows:1. With the increase of NaCl concentrations, seed germination percentage were95％、96.67％、90％、88.33％、45％、11.67％respectively, which showed a decreased trendafter an initial increase,and the length of radicle and germ also present the same trend. NaClconcentration at150mmol/L could inhibite seed germination significantly. NaClconcentrations greater than or equal to100mmol/L the length growth of radicle and germwere inhibited more obvious. MDA, Pro and CAT after seed germination were first raisedand then decreased，and Pro content were1.1、7.0、9.4、7.2、6.4times than thecontrol group. SOD and POD were reduced significantly in NaCl concentration greaterthan or equal to150mmol/L.2. With the increase of NaCl concentrations, stem length, plant height, leaf dry weightand fresh weight of cultured seedlings increased first and then down, but the increase wasnot significant. Root/Stems first falled and then rised. Root/Stems was minimum in NaClconcentration of50mmol/L,which was maximum in NaCl concentration of150mmol/L,which indicated that low NaCl concentration, Leaf area and water content decreased, andthe most significant decrease appeared in the concentration of150mmol/L.3. With the increase of NaCl concentrations, electrolyte leak and malonaldehydecontent increased, the increase was obvious most in150mmol/L NaCl concentrations. Procontent increased first and then decreased, the highest value was in150mmol/L NaCl.Protective enzymes SOD, POD and CAT showed a downward trend after the first rise,protective enzyme activity changes were little in25mmol/L NaCl, which had the mostactivity in150mmol/L NaCl.4. With the increase of NaCl concentrations, chlorophyll a, chlorophyll b and totalchlorophyll content decreased, however, the change was little in25mmol/L NaCl concentration. Chlorophyll content decreased significantly in more than or equal to100mmol/L NaCl concentration. Chlorophyll a/b was declined first and then decreased, butnot significantly. Maximal fluorescence in dark adapted state (Fm), maximal photochemicalefficiency of PSⅡ(Fv/Fm), potential activity of PSⅡ(Fv/Fo), effective quantum efficiencyof PSⅡ(Fv’/Fm’), quantum efficiency of PSII photochemistry(фPSⅡ), photochemicalquenching coefficient (qP) and Electron transport rate(ETR) showed a downward trend,with the NaCl concentration and time increasing, downward trend was more and moresignificant. However, the parameters did not change significantly in25mmol/L NaCl,Non-photochemical quenching coefficient (NPQ) showed an upward trend,and the changewas not obvious in25mmol/L NaCl concentration, as the NaCl concentration and timeincreasing the change increased significantly.5. After NaCl stressing Calystegia soldanella seedings for10days, with NaClconcentration increasing, Na~+content of Calystegia soldanella seedlings roots, stems andleaves were increased, however, K~+content decreased, Na/K was increased with theincreasing of NaCl concentration, which were1.2、1.9、4.1、4.7and5.8times inthe root,1.0、1.2、1.4、3.2and3.7times in the stem,and1.2、1.3、2.7、4.9and5.5times than the control groups, indicating that seedlings accumulated Na+significantly,meanwhile inhibited the K+absorption of seedling. SK, Nadecreased after aninitial increase, indicating that seedlings increased the select transport ratio of K+, but thechange was little in25mmol/L NaCl.In short, Calystegia soldanella seed germination and seedling growth were normallevels in25mmol/L NaCl. When NaCl concentration was more than25mmol/L, seedgermination and seedling growth would be inhibited. Calystegia soldanella could start avariety of protection systems to adapt to salinity environment in50-100mmol/L NaClconcentration. While, it was in150-200mmol/L NaCl concentration that those indicatorswould reflect that the salt tolerance reduced significantly so that the growth and metabolismof Calystegia soldanella were inhibited seriously.