| Lead is a heavy metal pollutant that is not easily degraded in the soil.As camphor camphor is a unique economic tree species in my country,lead poisoning has seriously affected the quality of camphor wood,garden aesthetics and ornamental effects.Using camphor seedlings as the test material,a two-factor random test design was used to set 4 soil exogenous lead concentrations(0mg·kg-1,500mg·kg-1,1000mg·kg-1,2000mg·kg-1)and 3 The level of exogenous silicon(0mg · kg-1,1000 mg · kg-1,2000 mg · kg-1),by analyzing its growth index,physiological index to analyze the resistance of camphor camphor to heavy metal lead and silicon to heavy metal lead The impact of coercion,the results show:（1）Different silicon levels have different effects on the growth characteristics of Cinnamomum camphora seedlings under different lead contents.At the same silicon level,with the increase of soil lead content,the relative increase of plant height,relative increase of ground stem,biomass,total root length,and total root surface area of camphor seedlings showed a law of increasing first and then decreasing.The maximum value is at 500mg·kg-1 lead content,and the worst growth is at 2000mg·kg-1 lead content;height-diameterratio basically shows a steady upward trend;at the same lead content,at1000 mg · kg-1 silicon level the relative growth of plant height and ground diameter of seedlings,biomass,total root length,and total root surface area are greater than 0 mg·kg-1 silicon level,and less than 0 mg·kg-1 silicon level at2000 mg · kg-1 silicon level.The 1000 mg · kg-1 silicon level alleviated the inhibitory effect of lead stress on Cinnamomum camphora seedlings,and the growth inhibition effect of Cinnamomum camphora seedlings was enhanced at the 2000mg·kg-1 silicon level.（2）Different silicon levels have different effects on physiological characteristics of Cinnamomum camphora seedlings under different lead concentrations.At a certain silicon level,with the increasing lead concentration,the chlorophyll content of Cinnamomum camphora seedlings showed a tendency of low promotion and high inhibition,and all reached the maximum value at the lead concentration of 500 mg·kg-1;soluble sugar,soluble protein,free Proline,malondialdehyde（MDA）,superoxide dismutase（SOD）,peroxidase（POD）,and catalase（CAT）basically showed a steady increase,reaching 2000mg·kg-1 Pb The maximum value;at a certain silicon level,as the lead concentration continues to increase,the net photosynthetic rate（Pn）,stomatal conductance（Gs）,intercellular CO2 concentration（Ci）,and transpiration rate（Tr）of Cinnamomum camphora seedlings appear first The trend of decreasing after increasing also reached the maximum at the lead concentration of 500mg·kg-1.Chlorophyll,soluble sugar,soluble protein,free proline,superoxide dismutase（SOD）,peroxidase（POD）,hydrogen peroxide at 1000 mg· kg-1 silicon level of Cinnamomum camphora seedlings under a certain lead concentration Enzyme（CAT）,net photosynthetic rate（Pn）,stomatal conductance（Gs）,intercellular CO2 concentration（Ci）,transpiration rate（Tr）greater than 0mg·kg-1 silicon level,less than 2000 mg · kg-1 silicon level 0mg · kg-1 silicon level;whilemalondialdehyde（MDA）at 1000mg·kg-1 silicon level is lower than 0mg·kg-1silicon level,and at 2000 mg · kg-1 silicon level is 0mg · kg-1 silicon level increased.1000mg·kg-1 silicon level can reduce the inhibitory effect of lead stress on Cinnamomum camphora physiology.At 2000mg·kg-1 silicon level,the physiological inhibition effect its on lead stress is enhanced.（3）The results of the determination of lead content in the leaves,stems and roots of Cinnamomum camphora seedlings showed that the lead content in the underground part of Cinnamomum camphora seedlings was higher than the above-ground part in different treatment groups.At the same silicon level,with the increase of soil lead content,the lead content of the leaves,stems and roots of Cinnamomum camphora basically showed an increase law,2000mg·kg-1 lead content leaves,stems and roots lead content accumulated the most,1000mg·kg-1silicon The accumulation of lead content in the horizontal leaves,stems and roots is reduced.（4）By analyzing the growth characteristics and physiological characteristics of Cinnamomum camphora seedlings under different silicon levels and different lead concentrations,as well as the analysis of their membership functions,it can be shown that 500mg·kg-1 Pb + 1000mg·kg-1 Si treatment.At a certain lead concentration,the growth advantage of Cinnamomum camphora at 1000mg·kg-1silicon level is greater than 0mg·kg-1 silicon level,and the growth advantage at2000mg·kg-1 silicon level is less than 0mg·kg-1 silicon level,at 1000mg·kg-1silicon level can alleviate lead stress of Cinnamomum camphora seedlings,and2000mg· kg-1 silicon level can inhibit the growth of Cinnamomum camphora seedlings. |
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