| The absorption and accumulation of cadmium by different maize genotypes have certain regularity,and the remediation of cadmium in soil is also different.On the one hand,the absorption of cadmium in soil by maize is affected by external environment,on the other hand,there are significant differences among maize varieties.In this experiment,pot experiment was adopted.The response of different genotypes of corn Xiangnongyu 27(hereinafter referred to as N27)and Xiangnongyu 22(hereinafter referred to as N22)to cadmium pollution was studied,and the effects of different soil cadmium concentrations of1mg/kg,1.5mg/kg,2mg/kg,2.5mg/kg,3mg/kg,7mg/kg and blank groups(hereinafter referred to as C1,C2,C3,C4,C5,C6 and CK)1.For N22,a variety with high cadmium accumulation,the leaf area and plant height of maize plants were reduced by high cadmium concentration in the summer and spring seasons.the ear leaf area of C2N22 treatment was significantly higher than other treatments(except C6N22 in the second season),and the ear leaf length was mainly increased in the summer season and the ear leaf width was increased in the second season.The significant increase of leaf area is helpful to photosynthesis of corn and produce more carbohydrates;Compared with C6N22 treatment,the average weight per plant of C2N22 increased by 74.0% in two seasons,while compared with CKN22 treatment,the weight per plant of C2N22 did not decrease significantly.For varieties with low cadmium accumulation,the single plant weight showed a rule of first increasing and then decreasing.The single plant weight of C3N27 treatment was the heaviest,which was significantly increased by 21.3% on average compared with CKN27,showing that this concentration promoted the yield of N27 maize varieties,while the leaf area of C3N27 increased by only 4.1% compared with C6N27.Therefore,for varieties with low cadmium accumulation,the main reason for the increase of yield is not the increase of leaf area.2.Under different cadmium concentrations,the chlorophyll content of maize varieties with different genotypes showed different rules.The contents of chlorophyll a,b and c in maize variety N22 with high cadmium accumulation decreased gradually with the increase of exogenous cadmium concentration(except C2N22).Compared with CKN22,the contents of chlorophyll a,b and c in C2N22 treatment decreased by 30.9%,51.5% and 27.8%respectively,showing obvious inhibition.SPAD values of N22 varieties also showed similar rules.However,N27,a variety with low accumulation of cadmium,inhibited the increase of chlorophyll content in high concentration,but had no significant promotion and inhibition in low concentration.In the summer season,the cadmium concentration of C3N27 reduced chlorophyll a,b and c content in corn,while in the second season,it showed the opposite rule,but did not reach significant difference level.The law of SPAD value of N27 varieties is similar to that of chlorophyll content,but C4N27 treatment is significantly reduced by22.4% compared with C3N27 treatment,and the other treatments have no significant difference.3.The cadmium content in roots,stems,leaves and grains of all treatments increased gradually with the increase of cadmium concentration,and the rule of cadmium content in all organs was root > stem > leaf.For N22 with high cadmium accumulation,the cadmium content in roots of C1N22-C3N22 treatment increased gradually with the increase of cadmium concentration,but compared with CKN22 treatment,the cadmium content in roots and stems of C2N22 treatment increased by 12.5% and 11.1%,respectively.However,the cadmium content in leaves treated with C2N22 was significantly higher than that treated with CKN22,which increased by 24.7%.For N27 and C2N27 varieties with low cadmium accumulation,the cadmium content in roots and leaves was significantly higher than that in CKN27 treatment.Compared with C1N27 treatment,the cadmium content in roots and leaves of C3N27 increased by 9.8%,24.8% and 58.2% respectively in two seasons.For the change of grain cadmium content,the two seasons also showed different rules.In the second season,the cadmium content of each treatment increased significantly after the exogenous cadmium concentration was C2,but the cadmium content of each treatment with concentration 3 was within the national edible standard.In the first quarter,the cadmium content in maize grain increased significantly after C3 concentration,but there was no significant difference among the treatments before adding exogenous cadmium concentration 3.For grain partition transfer and enrichment coefficient,all treatments increased with the increase of Cd concentration.4.The change of available cadmium content in soil shows the same rule in two seasons,which increases with the increase of exogenous cadmium concentration,and the increase of low concentration(C1-C3)is less than that of C4-C6.C＿3 concentration is its inflection point.Compared with C＿3N＿27 and C＿3N＿22,the available cadmium in soil increased by 42.3%(40.0%-44.6%)and 43.7%(40.3%-47.1%)respectively.Compared with C2N27,C3N22 C2N22,the available cadmium in soil of C3N27 increased by only13.7%(8.3%-19.1%)and 11.1%(8.8%-13.3%)respectively.Therefore,in C6-C4 concentration range,compared with C3-C1 concentration range,the content of available cadmium in soil increased faster.The change rule of available nitrogen and available phosphorus content in soil is that the content first decreases and then increases with the increase of cadmium concentration,and C3 concentration is its inflection point.The reason may be that the maize plants were not inhibited at low cadmium concentration,but gradually inhibited after the cadmium concentration was C3,which led to the reduction of nutrients absorbed by the plants into the soil,thus increasing the content of available nitrogen and available phosphorus in the soil.To sum up,different genotypes of maize varieties have different responses to different cadmium concentrations in soil.For N27 with low cadmium accumulation,C3N27 is the best treatment.By increasing the ear leaf area and chlorophyll content,the photosynthesis of maize plants is promoted,and more carbohydrates are produced,thus increasing the yield.But also can effectively control the cadmium content in grains,and the C3 concentration is the soil cadmium threshold of the variety.For N22,C2N22,which has high accumulation of cadmium,the treatment is the best,which can effectively reduce the cadmium content in different parts of plants while increasing the yield.C2 concentration is the threshold of soil cadmium for N22. |
PDF Full Text Request