Study Of The Effect On Seed Germination And Seedling Physiological Characteristics In Three Drought-tolerant Plants To Ni Stress

With the development of industry, Nickel pollution is more and more serious inrecent decades. It has caused severe environmental pollution. Control of nickelpollution also appears more and more important. The phytoremediation has muchmerits than any other methods, it is the main way to repair nickel contamination ofheavy metals. Three kinds of drought-tolerant plants, Polygonum aubertii L. Henry、Robinia pseudoacacia L. and Sophora alopecuroides L., were selected here asmaterials and comparison of seed germination, seedling protection enzymes activityand photosynthetic pigment at different Ni treatments (0,5,50,100,300,500mg/L) areconducted in order to study the resistance mechanism. The results are summarized asfollows:（1）When Ni concentrations is5mg/L, the effect of Ni on the germinationpercentage, germination energy, germination index and vital index of P. aubertii andR. pseudoacacia are not significant (P＞0.05), and the effect on the germination indexof S. alopecuroides are not significant (P＞0.05), but the effect on the germinationpercentage, germination energy and vital index of S. alopecuroides is significant (P＜0.05). When Ni concentrations is50mg/L, the effect on the germination percentage,germination energy, germination index and vital index of S. alopecuroides is notsignificant (P＞0.05), but vital index is significant (P＜0.05). When Ni concentrationsis100mg/L above, the effect on the germination percentage, germination energy,germination index and vital index of three plants are significant (P＜0.05). When Niconcentrations between50mg/L with100mg/L, the effect on the germination indexand vital index of R. pseudoacacia is not significant (P＞0.05); the effect on thegermination index and vital index of S. alopecuroides is significant (P＜0.05); theeffect on the germination index of P. aubertii is not significant (P＞0.05), while vitalindex of P. aubertii is significant (P＜0.05). In seed germination stage, S. alopecuroideshas better tolerance to heavy metal nickel.(2) When Ni concentrations are5mg/L, the effect of Ni on the root and budlengths of seedlings of R. pseudoacacia is not significant (P＞0.05), but it issignificant(P＜0.05) on S. alopecuroides; the effect on the root lengths of seedlings ofP. aubertii is significant (P＜0.05), while bud lengths is not significant (P＞0.05). Seedling fresh weight of R. pseudoacacia increased slightly, but the effect on thefresh weight of seedlings of R. pseudoacacia is not significant (P＞0.05); Seedlingfresh weight of P. aubertii and S. alopecuroides were reduced, and the effect on thefresh weight of seedlings of P. aubertii is not significant (P＞0.05), while it issignificant (p＜0.05) on S. alopecuroides. When Ni concentrations is50mg/Labove, the effect on the root and bud lengths, the fresh weight of seedlings of threeplants are significant (P＜0.05), and have a Significantly downward trend; In the earlystage of seedling growth, P. aubertii has stronger resistance to heavy metal nickel.(3) When Ni concentrations is5mg/L, the chlorophyll content of three plants isall decreased, the effect of Ni on the chlorophyll a and chlorophyll b content ofseedlings of R. pseudoacacia and P. aubertii are not significant (P＞0.05), but it issignificant (p＜0.05) on S. alopecuroides The MDA content of three plants are notobvious difference compared with contrast. When the concentration of Ni is50mg/L,the MDA content of R. pseudoacacia increased significantly less than P. aubertii andS. alopecuroides. When the concentration of Ni between300mg/L with500mg/L, R.pseudoacacia and P. aubertii does not change significantly with chlorophyll b content,but it is significant (p＜0.05) on S. alopecuroides. The MDA content increasesrapidly with increasing of Ni concentrations in R. pseudoacacia, while the change in P.aubertii and S. alopecuroides is relatively flat.With the increase of Ni concentration, SOD content of P. aubertii showed outlow-high-low tendency, the SOD content was highest at the5mg/L Ni solutionconcentration. When the concentration of Ni is less than50mg/L, SOD content of R.pseudoacacia and S. alopecuroides showed a trend of rise. When the concentration ofNi is100mg/L, SOD content of S. alopecuroides began to decline, and SOD contentof R. pseudoacacia began to decline in300mg/L.When the concentration of Ni is less than100mg/L, POD and CAT content ofthree plants are on the rise; When the concentration of Ni is100mg/L, POD and CATcontent of P. aubertii began to decline; The concentration of Ni exceeds300mg/L,the CAT content of R. pseudoacacia and S. alopecuroides began to decline, while thePOD content of R. pseudoacacia and S. alopecuroides continue to rise.From the point of plant physiological characteristics, S. alopecuroides has greater tolerance and resistance under nickel stress.