Soil Science Department, University of São Paulo, Luiz de Queiroz College of Agriculture, Pádua Dias 11, Piracicaba, São Paulo, 13418-900, Brazil.
Crop Science Department, University of São Paulo, Luiz de Queiroz College of Agriculture, Pádua Dias 11, Piracicaba, São Paulo, 13418-900, Brazil.
Environ Sci Pollut Res Int. 2018 May;25(14):14083-14096. doi: 10.1007/s11356-018-1541-1. Epub 2018 Mar 8.
Nitrogen (N) can alleviate metal toxicity. However, as of yet, there have been no studies showing the efficacy of NO/NH in mitigating Cu toxicity. The objective of this study was to evaluate the Cu toxicity on the nutritional and productive attributes of Panicum maximum cv. Tanzania as well as the role of NO and NH ratios in nutritional homeostasis. The experiment was conducted using 3 × 4 factorial treatments arranged in a randomized complete block design with three replicates. The treatments were three NO/NH ratios (100/0, 70/30, and 50/50) and four Cu rates (0.3, 250, 500, and 1000 μmol L) in nutrient solution. Copper concentrations in the diagnostic leaves (DL) were highest in plants grown under 70/30 NO/NH ratios and a Cu rate of 1000 μmol L. In this combination, it was observed that DL had higher concentrations of NH, greater glutamine synthetase activity, lower chlorophyll concentration (SPAD value), and lower shoot dry mass, suggesting high disorders of nutritional homeostasis. Plants receiving N in the form of NO and 1000 Cu μmol L showed that DL had lower concentrations of Cu, higher concentration of chlorophyll, higher NO concentration, higher nitrate reductase activity, and higher NO accumulation in the roots, suggesting a reduction in disorders of nutritional homeostasis. The disorders on mineral uptake, N assimilation, and biomass production caused by Cu toxicity are shown to be affected by NO/NH ratios, and N supply via NO allowed for better homeostasis of the forage grass.
氮（N）可以减轻金属毒性。然而，目前还没有研究表明 NO/NH 在缓解铜毒性方面的功效。本研究旨在评估铜对潘帕斯草 cv.坦桑尼亚的营养和生产特性的毒性，以及 NO 和 NH 比例在营养平衡中的作用。该实验采用 3×4 因子处理，随机完全区组设计，重复 3 次。处理为三种 NO/NH 比例（100/0、70/30 和 50/50）和四种铜浓度（0.3、250、500 和 1000 μmol L）在营养液中。诊断叶片（DL）中的铜浓度在 70/30 NO/NH 比例和 1000 μmol L 铜浓度下生长的植物中最高。在这种组合中，观察到 DL 中 NH 浓度较高，谷氨酰胺合成酶活性较高，叶绿素浓度（SPAD 值）较低，地上部干重较低，表明营养平衡严重失调。以 NO 形式接受 N 和 1000 Cu μmol L 的植物表明，DL 中铜浓度较低，叶绿素浓度较高，NO 浓度较高，硝酸还原酶活性较高，根中 NO 积累量较高，表明营养平衡失调减轻。铜毒性引起的矿物质吸收、N 同化和生物量生产障碍受 NO/NH 比例的影响，通过 NO 供应 N 可使牧草更好地保持内环境稳定。
