| In order to investigate the effect of photosynthetic bacterial fertilizer and nano elemental selenium on the remediation of cadmium-contaminated canola(Lactuca sativa var longifoliaf.Lam),this master’s thesis uses a pot experiment to set up a control group(Control,CK),10 mg·kg-1 Cadmium(Cd)treatment group,2.0 mmol·L-1 selenium(Selenium,Se)treatment group,0.5 g·kg-1,1.0 g·kg-1,and 1.5 g·kg-1 photosynthetic bacteria(Photosynthetic Bacteria,PSB)Bacterial fertilizer treatment group,0.5 g·kg-1 PBS+10 mg·kg-1 Cd treatment group,1.0 g·kg-1 PBS+10 mg·kg-1 Cd treatment group,and 1.5 g·kg-1 PBS+10 mg·kg-1 Cd treatment group,0.5 g·kg-1 PBS+10 mg·kg-1 Cd+2.0 mmol·L-1 Se treatment group,1.0 g·kg-1 PBS+10 mg·Kg-1 Cd treatment group+2.0 mmol·L-1 Se treatment group and 1.5 g·kg-1 PBS+10 mg·kg-1 Cd+2.0 mmol·L-1 Se treatment group,different concentrations were studied The PSB and nano elemental Se treatment groups affected Cd-stressed rapeseed(Lactuca sativa var longifoliaf.Lam)plant height,chlorophyll(Chlorophyll),glutathione(Glutathione,GSH),malondialdehyde(MDA),and grain Cystathione peroxidase Sex(Glutathione peroxidase,GSH-Px)and PSB influence on heavy metal content in soil and lettuce.The results are as follows:Part One Effect of photosynthetic bacterial fertilizer on growth potential of oilseed rape.The pot experiment was used to treat each set of conditions.On the 1st,7th,14th,21st,and 28th days of cultivating lettuce,the plant heights of the control and treatment groups were measured with tape measure(The measurement location is:the upper part of the rapeseed),record the measured data,and then use SPSS software to analyze the data;after the rapeseed is mature,weigh the fresh leaves to determine the chlorophyll content.The results showed that Cd had an inhibitory effect on the plant height and chlorophyll content formation in rapeseed.After 14 days of Cd treatment,the inhibitory effect of the Cd treatment group was significantly reduced compared with the control(P<0.01);however,when soil Adding a certain amount of Se to the leaf can significantly promote the formation of chlorophyll in the leaves(P<0.01);when PSB bacterial fertilizer is applied,it can effectively increase the chlorophyll content in leaves of rapeseed rape in the Cd treatment group.When the PSB concentration is 0.5 g When kg-1 and 1 g·kg-1,PSB had no significant promotion effect on rapeseed plant height(P>0.05);when the PSB concentration was 1.5 g·kg-1,it could significantly promote the latter stage.Growth(after 21 days)showed a significant promotion effect(P<0.01);different concentrations of PSB had a certain mitigating effect on the growth of Cd-stressed rapeseed,which was expressed as follows:compared with the plant height of Cd-treated rapeseed,The plant height of Y.oleracea in the Cd treatment group with PSB was higher,and when the PSB concentration was 1.5 g·kg-1,the relief effect increased significantly(P<0.01).At the same time,the chlorophyll content in the leaves of Y.oleracea was increased.There was a significant increase(P<0.01).It was shown that when PSB concentration was 1.5 g·kg-1,PSB could significantly promote the growth of oilseed rape;however,after adding Se to the PSB+Cd treatment group,it had an inhibitory effect on the height of oilseed rape,of which 1.5 The inhibitory effect of g·kg-1PSB+Cd+Se treatment group was obvious(P>0.05);it promoted the chlorophyll content of oilseed rape,and it was significant when the PSB concentration was 0.5 g·kg-1(P<0.01).).Part Two Effect of photosynthetic bacterial fertilizer on antioxidant enzyme activities in rape.This experiment measured and compared the three enzyme activities of SGH,SGH-Px and MDA in each group,and verified the effects of photosynthetic bacterial fertilizer and nano-elemental selenium on antioxidant enzyme activities in cadmium-contaminated rape.The results showed that:Cd stress decreased the GSH content and GSH-Px activity and increased the MDA content in rape.PSB converts Cd into CdS compounds through assimilation sulfate reduction and desulfurase,and promotes Cd precipitation,thereby alleviating the toxic effects of free Cd on plants.The results show that when the PSB concentration is 1.5 g·kg-1,the increase of GSH-Px activity and the content of MDA in rapeseed can be significantly promoted,thereby increasing its resistance to Cd,but its effect on the content of GSH is not significant.Significantly.However,as an essential component of GSH-Px,Se element has a certain effect on the activity of GSH-Px,thereby enhancing the resistance of rapeseed to Cd.Part Three Effect of photosynthetic bacterial fertilizer on the content of heavy metals in soil and rape.The results show that:through the determination of heavy metal content in rapeseed from different treatment groups,we found that after applying Cd,the content of Cd in the leaves and soil of rapeseed in the Cd group increased significantly compared with the control group;while in the Se group,there was no significant change;In PSB,with the increase of PSB concentration,the Cd content in the leaves of rapeseed rape gradually decreased,and the content of Cd in the soil gradually increased;in the PSB+Cd group,the Cd content in leaves of rapeseed rape decreased compared with the Cd group,and with the PSB concentration Cd content in the leaves of rapeseed rape decreased significantly,while Cd content in the soil increased compared with the Cd group,and with the increase of PSB concentration,the Cd content in the soil increased significantly.The conclusions from the study are as follows:Firstly,Cd stress can significantly inhibit the growth of oilseed rape.The application of PSB has a significant promotion effect on the growth of rapeseed and can effectively alleviate the toxic effect of Cd stress on plants,and there is a significant dose-response relationship.Se mainly enhances the resistance of rapeseed to Cd by affecting enzymatic and non-enzymatic systems.PSB and Se have antagonistic effects in promoting plant growth,but there are synergistic effects in chlorophyll accumulation.The mechanism of action needs to be further studied.Secondly,Selenium has a certain effect on the activity of GSH-Px,thereby enhancing the resistance of rapeseed to Cd.The application of PSB has a significant promotion effect on protecting rapeseed from oxidative stress,can effectively alleviate the toxic effect of Cd stress on plants,and there is a significant dose-effect relationship.PSB and Se play a synergistic role in promoting plant antioxidant response.Thirdly,Cadmium stress will produce accumulation effect in rape.PSB can alleviate the toxic effect of Cd on rapeseed by preventing Cd from entering the rapeseed,and with the increase of PSB concentration,the inhibition is more significant,and there is a clear dose-response relationship.Obvious promotion.The effects of Cd-Se interaction and possible synergistic effects of PSB and Se on the absorption,transport and accumulation of Cd by crops are unknown,so further research and investigation are needed. |
