| Kummerowia striata is an annual herb of the legume family,which has the advantages of beautiful plant shape,strong biological nitrogen fixation ability,and wide ecological adaptability.The plant grows luxuriantly in the high manganese content section of the waste land of manganese ore,and can normally bloom and bear fruit.This shows that the plant has strong manganese tolerance and is an ideal candidate for bioremediation.In order to ascertain the morphological structure changes and physiological and biochemical responses of Kummerowia striata to manganese stress,this paper took Kummerowia striata in the manganese-contaminated area and Kummerowia striata in the non-contaminated area as the research objects,and conducted seed germination experiments and pot experiments under different manganese concentration stresses.The phenotype,microstructure,physiological and biochemical changes of cornflower from two sources.The research results are as follows:(1)The results of seed germination experiments showed that the germination potential,germination rate,germination index and vigor index of the Kummerowia striata seeds in the contaminated and non-contaminated areas gradually decreased with the increase of the manganese concentration.When the manganese concentration is higher than 15000 ?mol·L-1,compared with the control,the germination potential and germination rate of the Kummerowia striata in the non-contaminated area are higher than that in the contaminated area.With the increase of manganese concentration,the root dry weight and bud dry weight of the Kummerowia striata seedlings in the contaminated and non-contaminated areas showed a trend of rising first and then decreasing.The growth of grass is inhibited,and the inhibition effect of roots is higher than that of buds;compared with the control,the percentage of root dry weight reduction of Cornfield grass seedlings in non-contaminated areas(27.90%?77.54%)is higher than that of Cornfield grass in contaminated areas(10.00%?66.06%).(2)The pot experiment showed that as the concentration of manganese increased to 5000 ?mol·L-1,the poisoning symptoms of Kummerowia striata in the contaminated and non-contaminated areas became more and more obvious.The leaves showed slight greenness,and then brown spots appeared around the veins.Until the edge of the leaf is twisted and the recession shrinks,etc.,when the concentration of manganese is 20,000?mol·L-1,the leaf even withers and falls a lot.When the manganese concentration is higher than 5000 ?mol·L-1,compared with the control,the growth indexes of the Kummerowia striata in the contaminated area and the non-contaminated area are suppressed,and the percentage of the root length drop of Kummerowia striata in the non-contaminated area(17.40%?42.28%)is higher than the pollution Cornflower(5.25%?24.13%).(3)Observation of the microstructure of the leaves of Kummerowia striata showed that when the manganese concentration was higher than 5000?mol·L-1,the palisade tissue and sponge tissue in the contaminated area and non-contaminated Kummerowia striata became thinner and the differentiation was not obvious;compared with the control,the non-contaminated area The drops of various tissues in the leaves of cornflower were higher than those in the contaminated area.(4)The pot experiment results show that the Kummerowia striata has a certain accumulation effect on manganese,and its manganese content gradually increases with the increase of manganese concentration.When the manganese concentration was 20000 ?mol·L-1,the Mn2+content in the leaves of the Kummerowia striata in the contaminated area and the non-contaminated area reached 12553.03 mg·kg-1 and 8558.05 mg.kg-1,respectively,16.53 times and 13.41 times of the control.(5)The results of a week's stress of Kummerowia striata seedlings showed that with the increase of manganese concentration,the chlorophyll content,soluble protein content,soluble sugar content,proline content and peroxidase content of Kummerowia striata seedlings in contaminated and non-contaminated areas(POD)The activity showed a trend of increasing first and then decreasing.The content of malondialdehyde(MDA)gradually increased with the increase of manganese concentration.Compared with the control,when the manganese concentration was 15000 ?mol·L-1,the content of MDA in the contaminated area increased by 79.52%,and that in the non-contaminated area increased by 161.39%.The results of manganese stress for one month showed that with the increase of manganese concentration,the chlorophyll content,soluble sugar content,proline content,SOD activity and POD activity of the Kummerowia striata in the contaminated and non-contaminated areas showed a trend of increasing first and then decreasing.The soluble protein gradually decreased,the MDA content gradually increased,and the physiological indicators of the Kummerowia striata in the non-contaminated area were affected more than the Kummerowia striata in the contaminated area.The results of this study indicate that the tolerance of mangosteen in the contaminated area is higher than that in the non-contaminated area,and osmotic adjustment substances and antioxidant enzymes play an important role in plant resistance to manganese stress. |
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