| With the development of industrial and agricultural production,emissions of the three wastes,development and utilization of minerals,sewage irrigation,and the use of pesticides,herbicides,and chemical fertilizers,the soil,water quality,and atmosphere have been polluted seriously,resulting in incalculable harm on environmental deterioration,and social,economic and human development..Among them,the harm caused by cadmium pollution is increasing.Once the excess cadmium enters the environment,it is difficult to remove it especially after it enters the water cycle and the soil,and it will cause a variety of damages,such as the destruction of the biofilm structure,blocking the electron transfer chain,changing the enzyme activity,resulting in stomatal closure,destruction of DNA and RNA synthesis,etc.Large amount of heavy metal cadmium remains in the environment for a long time,which seriously threatens ecological balance,soil fertility and even human health.It is imperative to seek efficient Cd-contaminated soil phytoremediation technology.Therefore,the study started with the metal-binding protein(phytochelatin)of Phragmites australis,and studied the expression pattern of cadmium-resistance gene in the whole growth cycle by culturing with different concentration of cadmium solution,and absorbed and accumulated cadmium in the growth cycle of reed.The metal content and morphological characteristics provide a theoretical basis for the study and cloning of the expression characteristics of the subsequent reed-resistant cadmium gene fragments,and provide a basis for cultivating new cadmium-resistant plant varieties and improving the purification of wetland pollution.The main results are as follows:(1)Under the condition of irrigating cadmium,the accumulation of cadmium in roots of reeds was significantly increased.In the same growth period,the difference between the treatment of cadmium in each group and the control group(0.0 mmol/L)was extremely significant(p<0.01),and the accumulation of five extracted cadmium in the root of reed was greater than that of the control group.The accumulation of five extracted cadmium was significantly and positively correlated with the irrigated cadmium concentration(p<0.01),and the maximum accumulated amount was 3.0 mmol/L.With the growth of Phragmites communis,the accumulation of five kinds of extracted cadmium in the root of reeds will gradually increase.When the 5.0 mmol/l cadmium solution is irrigated,the accumulation of five kinds of extracted cadmium in roots at the spreading leaf stage is more obvious than before,and the subsequent growth period is 5.The increase of cadmium accumulation in extracted cadmium was smaller.Under the condition of 0.0mmol/L-3.0mmol/L irrigated,the accumulated amount of cadmium in the five extracted cadmium species was increased during the fast growing period,and then the growth period was 5 years later.The accumulation of cadmium in the extracted cadmium increased slowly,and the accumulation of five extracted cadmium in roots was the highest during the mature period.(2)Under the condition of irradiating all concentrations of cadmium solution,the accumulation of five kinds of extracted cadmium in stems of reed was significantly increased.During the same growth period,the difference between the treatment of cadmium in each group and the control group(0.0 mmol/L)was extremely significant(p<0.01),and the accumulation of five extracted cadmium in the stem of the reed was greater than that of the control group.The accumulation of five extracted cadmium was significantly and positively correlated with the irrigated cadmium concentration(p<0.01),and the maximum accumulated amount was 3.0 mmol/L.With the growth of Phragmites communis,the accumulation of five kinds of extracted cadmium in the stem of the reed was gradually increased.When the 5.0 mmol/L cadmium solution was irrigated,the accumulation of five kinds of extracted cadmium in the stem of the reed was more obvious than before,and the subsequent growth period was 5.The increase of cadmium accumulation in extracted cadmium was smaller.Under the conditions of irrigating at concentrations of 0.0mmol/L-3.0mmol/L,the accumulated amount of cadmium in the five extracted cadmium species was significantly higher than that before.The accumulation of cadmium in the extracted cadmium increased slowly,and the accumulation of the five extracted cadmium in the stem was the highest at the mature stage.(3)Under the condition of irradiating all concentrations of cadmium solution,the accumulation of five kinds of extracted cadmium in the reed leaves increased obviously.During the same growth period,the difference between the treatment of cadmium in each group and the control group(0.0 mmol/L)was extremely significant(p<0.01),and the accumulation of five extracted cadmium in the leaves of Phragmites communis was higher than that of the control group.The accumulation of five extracted cadmium was significantly and positively correlated with the irrigated cadmium concentration(p<0.01),and the maximum accumulated amount was 3.0 mmol/L.With the growth of Phragmites australis,the accumulation of five kinds of extracted cadmium in the leaves of Phragmites australis will gradually increase.When the 5.0 mmol/L cadmium solution is irrigated,the accumulation of five kinds of extracted cadmium in the leaves at the leaf spreading stage is more obvious than that before,and the subsequent growth period is 5 The increase of cadmium accumulation in extracted cadmium was smaller.Under the conditions of irrigating at concentrations of 0.0mmol/L-3.0mmol/L,the accumulated amount of cadmium in the five extracted cadmium species was significantly higher than that before.The accumulation of cadmium in the extracted cadmium increased slowly,and the accumulation of cadmium in the five extracted cultivars was the highest in the mature period.(4)Under the conditions of irradiating with different concentrations of cadmium solution,the accumulation of five kinds of extracted cadmium in roots,stems and leaves of Phragmites australis was larger than that in stems and leaves.Under the condition of irrigating the same concentration of cadmium solution,the accumulation of cadmium in the rhizome,leaf and stem of the reed showed an increasing trend with the growth period.In terms of the ratio of total Cd content in the five forms,the extracted cadmium(SCd)was dominant in the roots,stems and leaves of reeds at different growth stages,followed by acetic acid extracted cadmium(ACd)and deionized water.The proportion of cadmium(DCd),hydrochloric acid extracted(HCd),and ethanol extracted cadmium(ECd)is the smallest.The difference is that the accumulation amount of cadmium in reed roots is rapidly increasing in the fast growing period under the conditions of 0 mmol/L-3.0 mmol/L cadmium solution irrigation,and is slowly increasing after the fast growing period,and the maturity period reaches the maximum;At the concentration of 5.0mmol/L cadmium solution,the accumulation of cadmium in reed roots increased rapidly during the leafing period,then increased slowly,and reached maturity at the maturity stage.The accumulation of cadmium in reed stalks showed a rapid increase before the heading stage under different concentrations of cadmium solution irrigation,and then increased slowly,reaching a maximum at the maturity stage.The increase of cadmium accumulation in reed leaves was similar to the increase trend of cadmium accumulation in reed roots under different concentrations of cadmium solution irrigation.It also increased rapidly during the fast growing period,increased slowly after the fast growing period,and reached the maximum during the mature period value.(5)After irrigating cadmium solution,the plant height,stem diameter,internode length,number of internodes,and biomass increased at each growth stage of the reed.The height and stem diameter of the reed plant along with the concentration of cadmium solution in the same growing period the amount of change occurring during the increase was smaller,and the length of internodes,the number of internodes,and the amount of biomass of the reeds varied with the increase of the cadmium concentration.After irrigating cadmium solution,the plant height,stem diameter,internode length,number of internodes,and biomass of the reeds reached the maximum under the conditions of 3.0 mmol/L cadmium solution irrigation.With the growth of Phragmites communis,the plant height,stem diameter,internode length,number of internodes,and biomass of Phragmites communis increased with different concentrations of cadmium solution irrigation,except for the number of internodes that reached the maximum at the heading stage.The maturity period reaches a maximum value.Under the irrigated conditions of 0mmol/L-3.0mmol/L cadmium solution,the plant height,stem diameter,internode length,number of internodes and biomass of reed showed a continuous and rapid increase trend after leafing stage;Under the condition of 5.0mmol/L cadmium solution irrigation,the plant height,stem diameter,internode length,number of internodes and biomass of reeds have been increasing,but they have been increasing slowly after the leafing period,and are significantly lower than those of the control group and several other concentrations.Under the irrigation condition of 3.0mmol/L cadmium solution,the maximum plant height of reed reached 227.1cm in mature period;the maximum stem diameter of reed was 0.543 cm in mature period;the maximum length of reed during internode period was 25.9cm in mature period;The maximum number of reed internodes was 17 knots;the maximum reed biomass reached 1612.41 g during mature period.The irrigated concentration of cadmium solution was significantly or extremely significantly positively correlated with plant height,stem diameter,internode length,number of internodes and biomass,and the correlation coefficients were all above 0.90.There was a binomial relationship between plant height,stem diameter,internode length,number of internodes,and biomass and irrigated concentration of cadmium solution in Phragmites australis.(6)At the same growth stage,the content of GSH(reduced glutathione)in rhizome,stem and leaf of reeds increased with the increase of irrigation cadmium concentration,and GSH(reduced valley)of roots,stems and leaves of reeds under the condition of 5.0 mmol/L cadmium solution irrigation.The glutathione content reaches a maximum.Under the condition of irrigating the same concentration of cadmium solution,GSH(reduced glutathione)content in roots of reeds showed an increasing trend with the growth period,and the content of GSH(reduced glutathione)in the roots of reeds reached the mature stage of reeds.The maximum;and GSH(reduced glutathione)content in stems and leaves of reeds will increase first and then decrease with changes in the growth period of reeds.The reed stems and leaves in the heading stage of reeds The GSH(reduced glutathione)content reaches a maximum.By comparing the GSH(reduced glutathione)content between the three parts of the rhizome of the reed rhizome,it can be found that GSH(reduced glutathione)in the rhizome leaf of the reed during the same growth period under the conditions of irradiating with different concentrations of cadmium solution.The content is always the highest in the root,followed by the leaves,and the GSH(reduced glutathione)content in the stem is the lowest.(7)The ?-ECS activity in reed roots increased with the increase of irrigation concentration during the germination,leaf spreading and rapid growth stages of reeds under different concentrations of cadmium solution irrigation conditions,heading date and maturity phase.At the same time,the ?-ECS activity in the root of Reed was increased first and then decreased with the increase of irrigated concentration of cadmium solution;the ?-ECS activity in the stem of Phragmites communis was in the germination,leaf development,rapid growth and heading stages of reed.The ?-ECS activity in the stems of reeds first increased and then decreased as the irrigated concentration of cadmium solution increased.The ?-ECS activity in the reeds sprouted in the reeds.During the leaf stage and leaf stage,they all increased with the increase of irrigation concentration.At the fast growth stage,heading stage and maturity stage,the ?-ECS activity in the reed leaves first increased and then decreased with the increase of the irrigated concentration of cadmium solution trend.Under the same irrigation conditions,the ?-ECS activity in the rhizomes,leaves,and stems of reeds increased first and then decreased with the growth of the reeds.The ?-ECS activity in the roots appeared the maximum in the fast growing stage,and the ?-ECS activity in the stems.During the leafing stage,the maximal value of ?-ECS activity appeared at the heading stage.(8)Based on the logistic curve-based regression analysis of the ?-ECS activity of Phragmites communis under irrigated cadmium solution,the intrinsic rate of growth of ?-ECS activity of reed urophylla under different concentrations of cadmium solution irrigation conditions was not changed significantly.The growth of Phragmites australis has little effect on the ?-ECS activity of Phragmites australis,and the irrigation of cadmium in different concentrations has a greater effect on the environmental capacity of Phragmites communis ?-ECS activity.That is,the higher the cadmium concentration,the more the ?-ECS activity of Phragmites australis can be accommodated high. |
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