| In this experiment,the sweet sorghum hybrid Liaotian 1 was used as the experimental material,processing for five different cadmium concentration?0,50,100,150,200,mmo/L?and applying2.0×10-33 mol/L or 3.0×10-33 mol/L under the treatment of200?moL/L cadmium stress.Seed germination characteristics,seedling growth,antioxidant enzyme activity and isoenzyme expression,leaf chlorophyll content,fluorescence parameters?Fv/Fm?qP??PS??NPQ?,photosynthetic parameters?Pn?Gs?Ci?Tr?,light response curve?Pmax???Rd?LSP?LCP?,cadmium enrichment effect were determined separately,aiming to find out from a physiological point of view The effects of cadmium stress and calcium application on the growth of sweet sorghum and cadmium uptake provide a reference for the development of energy crop sweet sorghum using marginal land and heavy metal contaminated soil.The main findings are as follows:1)The cadmium treatment at 200?mol/L significantly affected the normal germination of sweet sorghum seeds.The germination potential,germination rate,germination index and vigor index of sweet sorghum seed were significantly lower?P<0.05?than the control group.Calcium application can not alleviate the inhibitory effect of cadmium on seed germination.2)With the increase of cadmium concentration,the activities of SOD and POD in sweet sorghum seedlings showed an increasing trend,while the activity of CAT was reversed.The activity of APX showed different trends with different treatment concentrations,but the overall time was prolonged with the stress time.In the early stage of stress,new S4 and S2 bands appeared in the isozyme profile of superoxide dismutase,and new P3 and P2 bands appeared in peroxidase isoenzyme.Calcium application can alleviate the induction of cadmium against oxidase activity,and the addition of 3.0×10-3mol/L calcium is most obvious.3)The medium and high concentrations of cadmium stress reduced the chlorophyll content of sweet sorghum leaves,which led to a significant decrease in Pn,Gs,Tr,Fv/Fm,?SII,qP,Pmax,?,Rd and LSP,and a significant increase in NPQ,Ci and LCP.Adding different concentrations of calcium can alleviate the inhibition of cadmium on photosynthesis of sweet sorghum,and the application of 3.0×10-33 mol/L calcium is the best.4)Cd stress of greater than or equal to 50?mol/L inhibited the growth of sweet sorghum seedlings.With the increase of cadmium treatment concentration,the plant height,fresh weight of shoots,dry weight of shoots and shoots of sweet sorghum seedlings decreased significantly.Adding different concentrations of calcium can alleviate the inhibitory effect of cadmium on the growth of sweet sorghum,and increase its biomass on the basis of cadmium stress.5)Sweet sorghum seedlings have certain cadmium enrichment ability.With the increase of cadmium concentration,the cadmium concentration in the aboveground and underground parts of sweet sorghum increased significantly.Under the cadmium stress,the tiling efficiency of sweet sorghum decreased due to the decrease of biomass,especially the enrichment and enrichment of whole plants.Efficiency decreases with increasing stress concentration.The application of calcium can reduce the cadmium concentration in the lower part of the sweet sorghum,and significantly increase the cadmium accumulation of the plant.In summary,cadmium stress inhibited the germination and seedling growth of sweet sorghum seeds.Under cadmium stress,sweet sorghum seedlings could reduce the damage caused by reactive oxygen species under stress by regulating the activity of antioxidant enzymes.Cadmium stress reduced the chlorophyll content of sweet sorghum seedling leaves and decreased photosynthesis,which inhibited the growth of seedlings.The cadmium content of sweet sorghum plants increased significantly under cadmium stress.Exogenous calcium can not alleviate the inhibitory effect of cadmium on the seed germination of sweet sorghum,but it can alleviate the induction of cadmium on the antioxidant activity of seedlings,reduce the damage to photosynthetic system,reduce the cadmium concentration in the underground,to maintain normal growth and increase plant enrichment.The amount of calcium added by 3.0×10-3mol/L is most obvious. |
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