| Nowadays,environmental degradation,including soil pollution of heavy metals t h r e a t e n i n g p e o p l e 's h e a l t h a n d l i f e b e c a u s e o f h u m a n a c a t i v e s s u c h a s mining,smelting,garbage piling up and burning.Unlike organic pollutants,heavy metals can not be degraded by micro-organisms into the environment.Soil highly toxic heavy metals Cd,can not only make the degradation of soil fertility,crop yield and quality decline,deterioration of water environment,but aslo can enter the body through the food chain and ultimately harm to human health.Thus,to repair Cd contaminated soil is imminent.Compared with the traditional repair technology,more a n d m o r e r e s e a r c h h a s f o c u s e d o n h e a v y m e t a l t o l e r a n c e i n p l a n t s a n d cumulative.Tree species of poplar root system,bio-capacity,long growth cycle of BCF of heavy metals is high,and the ability to transport the aerial parts of the strong,may in the long term for cadmium contaminated soil completely repaired,and generally does not enter food chain,do no harm to the human body,and therefore is an ideal material bioremediation of heavy metals.In recent years,The role of SA in plants resistance to abiotic stress(heavy metals,high temperature,low temperature,stress,etc.)research also began to be widely concerned.SA pre-treatment or treatment can alleviate heavy metal poisoning of plants to some extent,but different organizations or different plants of the same plant in SA induction mechanism of resistance to heavy metal may vary.To study the physiological regulation law of SA a n t i-t o x i c h e a v y m e t a l s C d i n t h e g r o w t h c o n d i t i o n s,p h y s i o l o g i c a l a n d biochemical,seedings of Populus ×cathayana were treated with 0 or 150?M for 28 days in combination with 0 or 100?M exogenous SA.the following results were obtained:(1)Cd treatment resulted in Populus ×cathayana roots and leaves have accumulated a large amount of Cd.Result in photosynthetic pigments content decreased,affecting photosynthesis,inhibited the growth of the aerial parts and roots,thus reducing biomass.Cd treatment significantly inhibited photosynthetic rate,stomatal conductance,transpiration rate and leaf surface area.However,applied exogenous SA stomatal conductance and transpiration rate and net photosynthetic rate increased to certain extent.Relative to the control,Cd and exogenous SA treatment Significantly reduced the content of chlorophyll and carotenoid.And with respect to the single Cd treatment,exogenous SA significantly improved after the carotenoidcontent.(2)Cd treatment led to roots,stems,bark and leaves have accumulated large amounts of Cd,but after the application of exogenous SA roots,stems,bark and leaves of Cd concentrations were significantly lower.(3)Cd treatment resulted in Populus ×cathayana roots and leaves O2-,H2O2 content increased,with respect to separate the Cd,Cd and SA treatment reduced the roots and leaves of O2-,H2O2 content;Single Cd treatment resulted in a rise in Populus×cathayana root and leaf MDA content.With respect to separate the Cd,Cd and SA treatment reduced the content of MDA.Thiols(RSH)In plants important chelating substances,have an important role in plant resistance to heavy metal poisoning aspect.In our study,Cd treatment resulted in Populus ×cathayana roots and T-SH and the accumulation of leaves ASC,but after the application of exogenous SA,with Respect to separate the Cd,T-SH and ASC levels have decreased.The above findings suggest that 28 days of treatment in Cd Yang Populus×cathayana produced toxic effects,but on the basis of exogenous SA alleviated the toxic effect of Cd in Populus ×cathayana from the physiological and biochemical indicators applied. |
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