[Effects of cadmium on the growth and nitrogen metabolism in Brassica chinensis].
Hydroponic culture was conducted to study the effect of Cd on the growth, metal accumulation and nitrogen metabolism in Brassica chinensis. The enzymatic activities of nitrogen metabolism including nitrate reductase (NR), glutamine synthetase (GS) and GS-transferase as well as the concentrations of chlorophyll, free proline, soluble protein, NO3(-) -N, NH4+ -N and nutrients in Brassica chinensis were determined. Results indicated that the addition of Cd reduced the content of the soluble protein and the accumulation of Cu, Ca, Fe and Mg, but promoted the P uptake. Low level of Cd (1 mg x L(-1)) could significantly increase the biomass and the content of chlorophyll of Brassica chinensis and the activities of NR, GS and GS-transferase when compared to control plants. However, when the Cd levels were above 2.5 mg x L(-1) in the culture medium, the activities of these enzymes were inhibited. Accordingly, the contents of NO3(-) -N, NH4+ -N, free proline and the activity of protease in the leaf of Brassica chinensis increased significantly. These results suggested that Cd addition could interfere with the assimilation of N in Brassica chinensis. The increase of free proline might alleviate the toxicity of ammonium in Brassica chinensis.
Yu
Fang-ming
FM
School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China. fmyu1215@163.com
Qiu
Rong-liang
RL
Tang
Ye-tao
YT
Ying
Rong-rong
RR
Zhou
Xiao-yong
XY
Zhao
Xuan
X
Hu
Peng-jie
PJ
Zeng
Xiao-wen
XW
D001937:Brassica / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D002104:Cadmium / Q000494:pharmacology*; D002734:Chlorophyll / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D050901:Nitrate Reductase / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D011392:Proline / Q000378:metabolism*
D002104:Cadmium; D002734:Chlorophyll; D011392:Proline; D050901:Nitrate Reductase; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen