不同氮素形态配比对Cd胁迫下黑麦草生长特性的影响

The Effect of Different Combinations of Nitrogen Forms on Growth and Physiological Traits of Ryegrass under Cd S tress

【目的】探讨水培条件下不同氮素形态配比对Cd胁迫下黑麦草生长及生理特性的影响。【方法】在再生水水培条件下对黑麦草进行重金属Cd胁迫处理,研究了不同氮素处理(硝态氮铵态氮配比分别为100/0、75/25、50/50、25/75和0/100)下黑麦草中Cd的积累特性和生长、生理响应。【结果】在0.01 mg/L Cd胁迫条件下,适当增加硝态氮能促进黑麦草株高和根长的生长;在Cd胁迫处理下,铵态氮比例由25%上升到100%时,会促进黑麦草地上部对Cd的吸收;在10 mg/L Cd胁迫条件下,黑麦草MDA量在不同硝铵比水平下都低于0.01 mg/L Cd胁迫条件下的,而且在硝铵比100/0处理下最低;在Cd胁迫处理下,当铵态氮比例由50%上升到100%时,黑麦草中的CAT和POD活性升高。【结论】适当增加铵态氮有利于黑麦草地上部对Cd^(2+)的吸收,而且可以降低Cd胁迫对黑麦草的损伤。

【Objective】Nitrogen exists in different forms which have different effects on soil biogeochemical processes and plant growth and nutrients acquisition.The purpose of this paper is to investigate the impact of combinations of different nitrogen forms on the growth and physiological traits of ryegrass in hydroponic culture under Cd stress.【Method】We used treated wastewater as the hydroponic culture and grew the ryegrass by contaminating the culture with Cd concentration set at 0.01 and 0.1 mg/L,respectively.The nitrogen was nitrate and ammonium with the nitrate:ammonium ratio being set at 100∶0,75∶25,50∶50,25∶75 and 0∶100.In each treatment,we measured the physiological traits of the plant【Result】When the Cd concentration was 0.01 mg/L,increasing nitrate application promoted the growth of both roots and shoots,as well as absorption of Cd by the ryegrass when the nitrate:ammonium ratio increased from 25%to 100%.When Cd concentration increased to 10 mg/L Cd,the MDA content in the ryegrass was lower than that at 0.01 mg/L concentration,regardless of the nitrate:ammonium ratio.The content of MDA in the ryegrass under Cd stress was the lowest when nitrate:ammonium was 100∶0.We also found that Cd stress boosted the activities of CAT and POD in the ryegrass when the amount of ammonium increased from 50%to 100%.【Conclusion】Increasing ammonium in the nutrient solution benefited Cd^(2+) absorption by the ryegrass,thereby reducing its detrimental impact on ryegrass growth and development.