Effects Of Chromium Stress On The Chrome Absorpiton, And Ascorbate-Glutathione Cycle In Cabbages (Brassica Chinensis L.)

Different varieties of Brassica chinensis L. were used with hydroponic experiments andpot experiments under different concentrations of chromium treated in this study. Theabsorption and accumulation of Cr of different varieties of Brassica chinensis L.was studied;Moreover, the antioxidant system and ascorbate-glutathione cycle were also investigated tostudy the effect of Cr to the growth of Brassica chinensis L.. The main results of this researchare as follows:1、The content of chrome and activities of antioxidant enzymes in six varieties ofcabbages （Brassica chinensis L.） were studied with different concentrations of Cr³⁺.Theresults showed that it have differents in contents of chrome and activities of antioxidantenzymes among different genotypic cabbages. The biomass was decreased（P<0.05） with theincrease of Cr³⁺concentration. The chromium in Aikangqing and Jimaocai are lower thanLvxiu, Huangxincai, Wuyueman and Qibaoqing. Under250mg·kg^-1Cr³⁺treatment, the Crtranslocation factor in Aikangqing and Jimaocai were0.18and0.19, its were lower thanHuangxincai、Lvxiu, Wuyueman and Qibaoqing compared to control （0.28、0.21、0.22and0.20）, because of Cr absorption of root were bigger than upper part. The activities of SOD、POD and CAT in leaves significantly increased than control. Generally speaking, Aikangqingand Jimaocai have a lower chrome absorption and higher activities of antioxidant enzymes.Aikangqing and Jimaocai were low-accumulation of chrome cabbages.2、 The content of phytochelatins and the activities of key enzymes ofAscorbate-glutathione cycle in varieties of Aikangqing and Lvxiu were studied with differentconcentrations of Cr³⁺.The results showed that the contents of phytochelatins and antioxidantincreased with the increase of Cr³⁺concentration in both varieties.Under high concentrationof Cr³⁺(250mg L^-1),O₂^-contents in leaves of cabbages are significantly increased（P<0.05）,and the increased amount of Aikangqing is lower than that of Lvxiu. AsA and GSH contentsin leaves of Aikangqing are significantly increased compared to control （P<0.05）,while thoseof in Lvxiu are not significantly increased（P>0.05）. DHA and GSSG contents in Aikangqingare1.87and1.72times as much as control and those were1.98and1.94times as much ascontrol in Lvxiu, respectively. 3、 The activities of key enzymes in AsA-GSH increased with the increase ofCr³⁺concentration.The content of phytochelatins（PCs） and the activity of ascorbte peroxidase（APX）, dehydrateasorbate reductase（DHAR） in Aikangqing were30.9%、38.9%、45.2%higher than control under the concentration of250mg·L-1Cr³⁺treatment, respectively,whilethose in Lvxiu were11.5%、30.5%、43.0%higher than control,respectively. In conclusion,Aikangqing has a higher activities of key enzymes of AsA-GSH and phytochelatins underCr³⁺stress, this may be the physiological reasons why different varieties of cabbages havedifferent chromium-resistances.