低氮胁迫对不同氮效率玉米品种苗期叶片碳氮代谢的影响

研究低氮胁迫对不同氮效率玉米品种幼苗生长及叶片碳氮代谢的影响,分析比较不同氮效率玉米品种对低氮胁迫响应的差异。采用水培方法,以氮高效品种郑单958、正红311和氮低效品种川单428、先玉508为试验材料,在低氮胁迫(0.04 mmol/L)、正常氮(4 mmol/L)和低氮恢复处理3个氮水平下,分别测定苗期干物质积累量、叶片碳氮代谢产物含量及碳氮代谢相关酶活性,比较不同氮效率品种间的差异。结果表明,低氮胁迫显著降低玉米叶片和整株干物质重量、叶片氮代谢指标(硝酸还原酶和谷氨酰胺合成酶活性、可溶性蛋白和游离氨基酸含量),提高根系干重、根冠比、叶片碳代谢指标(蔗糖合成酶和蔗糖磷酸合成酶活性、可溶性总糖和淀粉含量)。不同品种间各指标的变化幅度随着时间的延长表现出不同规律,氮高效品种在氮素胁迫下对碳氮代谢的平衡能力更强,受低氮环境影响较小,植株的恢复能力较强,对胁迫环境具有更强的耐性和适应性。

Effects of Low Nitrogen Stress on Carbon-nitrogen Metabolites and Related Enzyme Activities in Leaves of Maize Varieties with Contrasting Nitrogen Efficiency at Seedling Stage

The effects of low nitrogen(N) stress on growth and metabolism of carbon(C) and N in leaves of maize varieties with contrasting N efficiency at seedling stage were investigated, the differences in response to low nitrogen stress in different nitrogen efficiency maize varieties were also analyzed and compared. A hydroponic experiment was carried out with two N-efficiency varieties(ZH311 and ZD958) and two N-inefficient varieties(CD428 and XY508) as the experimental materials and two N levels. The experiment consisted of three N levels, LN-0.04 mmol/L, CK-4 mmol/L and Discover-N. The dry matter accumulation, the content of C and N metabolites in leaves and the activities of enzymes related to C and N metabolism were measured respectivelyto compare the differences in contrasting N efficiency varieties. The main results showed that, low N stress significantly decreased the dry matter weight of plants and leaves, the indexes of N metabolism(the contents of soluble protein and free amino acid, the activities of nitrate reductase and glutamine synthase), and increased the the root weight, root/shoot ratio, and the C metabolism indexes(the contents of soluble sugar and starch, the activities of sucrose synthase and sucrose phosphate synthase. The variation range of each index between different varieties showed different regularity with the extension of time. Nitrogen efficient varieties have a stronger ability of C and nitrogen metabolism, less influence of low nitrogen environment, stronger recovery ability of plants, and stronger tolerance and adaptability to stress environment.