| Rosa rugosa-cv is one of the traditional rare flowers,and is also a courtyard greening tree speciesbecause of good ornamental value in China.In recent years,the heavy metals such as Cu,Cd,Pb and other pollution are increasing because of the widespread use of electronic products and the rapid growth of municipal waste.Rosa rugosa-cv can be used as the purifying species of the heavy metals and pollutants because of the characteristic of root shallow.Two years old Rosa rugosa-cvis selected as experimental object introduced from Holland,and six concentration gradients is set in the potted experiment.The stress effect on the growth,physiology and photosynthesis of Rosa rugosa-cv is analyzed underthe Cu,Cd and Pb of six concentrations.Besides that,theabsorption,accumulation,translocation characteristics,subcellular distribution and chemical forms under the different Cu,Cd and Pb heavy metals concentrations in Rosa rugosa-cv is also studied.The study on Rosa rugosa-cv growth status under the Cu,Cd and Pb stress is the key in this paper,which can provide the theory basis for the ecological restoration and afforestation tree species selection.The results are as follows:1.Effects ongrowth status of Rosa rugosa-cvseedingunder Cu,Cd and Pb stress conditionsThe heavy metaloflow concentration,which is Cu<400mg·kg-1,Cd<50mg·kg-1 and Pb<800mg·kg-1,takes on good growth status for the Rosa rugosa-cv seeding.Compared with contrast sample,the growth indexes of Rosa rugosa-cv,such as plant height,root length,ground stem,fresh weight,dry weight,are promoted under the heavy metaloflow concentration.However,with the increasing of stress concentration and time,Rosa rugosa-cvseeding takes on yellow leaf edge,lose green of leaves,brown spots and short plants.The results showed that the growth indexes of Rosa rugosa-cv will be inhibited under the higher stress concentration condition,and there is single plant death until the experiment end.2.Effects on Physiological Indexes of Rosa rugosa-cv seedling due to the heavy metals Cu,Cd and Pb stressWith the low concentration of the heavy metals Cu,Cd and Pb stress aforementioned,the content of chlorophyll a and b,a+b as well as Carotenoid have increased compared to control CK in Rosa rugosa-cv leaf.However,the total content of aforementioned indicators showed a downward trend with the increase of stress concentration of that 3 heavy metals,and Chlorophyll a/b increased gradually.The net photosynthetic rate(Pn)and transpiration rate(Tr)of Rosa rugosa-cv seedling are higher than those in low Cu,Cd and Pb stress,and decreased in a increasing concentration.which are lower than contrast one and was similar to the trend of diurnal variation of photos ynthesis like the "Two-hump" curve,however,the two hump occurred at 10:00 a.m.and aroun d 14:00 p.m.,and the valley occurred around 12:00a.m.And there is a typical "Photosynthesis-Noon break" phenomenon.3.Effects on the absorption and repair ability of Rosa rugosa-cv seedling due to the heavy metals Cu,Cd and Pb stressThe contrast ratio as well as contents of Cu,Cd and Pb in root,stem and leaf of Rosa rugos a-cv seedling plants increased with the increase of Cu,Cd and Pb stress concentrations(P < 0.05),and the root > stem > leaf part,in which the average value of Cd’s concentration coefficient in different parts is about 1(1.091,0.889,0.837),and the average value of the transfer coefficient is greater than 1.The Rosa rugosa-cv is one of the most worthy to concentrate on repairing Cd’s "dominant" plants which has strong enrichment and transfer ability to heavy metal Cd,but not up to hyper accumulator standards,It’s shows a relatively weak concentration and transfer ability to Pb and Cu when the enrichment coefficient and transfer coefficient of Cu and Pb in the a bove parts were lower than Cd.4.The subcellular distribution of the stress of heavy metals Cu,Cd and Pb in Rosa rugosacv seedlingIt’s the main reason for the good tolerance of the Rosa rugosa-cv seedling to Cu,Cd and Pb poll ution stress that vacuoles and soluble parts,cell walls and residues were the main subcellular bi nding sites of Cu,Cd and Pb in roots,stems and leaves of Rosa rugosa-cv seedling,as well as a less contents of Cu,Cd and Pb in the cell membrane and organelle.5.Distribution characteristics of heavy metals in Cu,Cd and Pb stress in Rosa rugosa-cv seedlingThe contents of Cu,Cd and Pb in different chemical forms of root,stem and leaf of Rosa rugosa-cv seedlings showed an upward trend with the increase of stress concentration of Cu,Cd and Pb.Cu,Cd and Pb exist in the Rosa rugosa-cv seedling mainly in the form of "inert state" which is less toxic HCl extraction,acetic acid extraction and sodium chloride extraction.And that 3 heavy metals are fixed in plants due to their poor mobility. |
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