铜胁迫对两种不同来源长萼鸡眼草生长及氮代谢的影响

Effects of Copper Stress on Growth and Nitrogen Metabolism of Kummerowia stipulacea(Maxim.)Makino from Two Different Sites

采用苗期水培的方法,研究铜胁迫和营养缺失及二者的复合作用对矿区和非矿区长萼鸡眼草生长及氮代谢的影响差异。结果表明,植物吸收的Cu绝大部分分配在植物的根部。Cu胁迫使植物组织中硝态氮(NO-3)含量和硝酸还原酶(NR)活性降低,使植物叶中铵态氮(NH+4)含量和谷氨酰胺合成酶(GS)活性升高,植物生物量减少。Cu胁迫下矿区植物叶中Cu含量、根中GS活性比非矿区的低,矿区植物叶生物量、组织中NR活性比非矿区的高。营养缺失使植物组织中NH+4含量、NO-3含量、NR活性、GS活性显著降低,根生物量显著增加,且矿区植物叶中GS活性的变化比非矿区的少。Cu胁迫营养缺失复合作用使植物组织中Cu含量、叶中GS活性显著升高,使根生物量、根中NR活性显著降低,且矿区植物叶中Cu含量增加的比非矿区的少。低营养胁迫可促进长萼鸡眼草对外源Cu的吸收,同时也刺激了植物根的生长,Cu胁迫和营养缺失环境下非矿区植物氮代谢的紊乱程度要比矿区的高,来源于矿区的植物对贫瘠和高Cu环境表现出更强的适应性。Cu及营养缺失对植物氮代谢的影响是非常复杂的,与植物组织中可利用氮和碳的改变有关,也与植物组织中酶活性的直接改变有关。

A research was made on the effects of copper stress and nutrient deficiency as well as their combinational action on growth and nitrogen metabolism of Kummerowia stipulacea （Maxim.） Makino from a copper mine-field and from an uncontaminated one by using solution culture of seedlings. The results showed that the copper absorbed by the plant was mostly distributed in the root, and the content of nitrate nitrogen and nitrate reduetase （NR） activity in the plant tissue decreased under copper stress, with the ammonium nitrogen （NH4^＋）content and glutamine synthetase （GS） activity in the leaf increasing and the plant biomass decreasing. Under the copper stress, copper content in the leaf and GS activity in the root of the plant from a eoper mine field site were lower than those from the uncontaminated one, while the biomass of the leaf and NR activity in the tissue of the plant from the mine field site were higher than from the uncontaminated one. Nutrient deficiency made NH4^＋ and NO3^- contents and NR and GS activities in the plant tissue decrease significantly, while causing the biomass of the root to increase substantially. Furthermore, the activity of GS in the leaf of the plant from the mine site changed less greatly than that from the uncontaminated one. The combinational action of both Cu stress and nutrient deficiency made copper content in the plant tissue and GS activity in the leaf increase significantly, while causing the biomass of and NR activity in the root to decrease substantially. Besides, the content of copper in the leaf of the plant from the mine site increased less than that from the uncontaminated one. Thus, it can be concluded that the nutrition deficiency stress could promote the absorption of exogeneous copper by Korean Lespedeza Kummerrowia stipulacea （Lespedeza stipulaeea） and the growth of the root simultaneously, while under the combined stress of copper stress and nutrient deficiency, nitrogen metabolism in the plant from the uncontaminated site would be more disturbed than that in the plant from the copper mine field one which displayed more adaptability to the barren environment of high copper content. Effects of copper stress and nutrient deficiency on nitrogen metabolism in the plant related not only to changes of nitrogen and carbon available in plant but also directly to changes of enzyme activity in the plant tissue.