Optimum fertilization is one of the challenges to agricultural sustainability. Understanding the physiological and biochemical response of plants to available nutrients is important for optimization of crop management practices. Present study investigated the effects of different levels of N fertilizer (N₀ = 0 kg ha⁻¹ [Control], N₁ = 140 kg ha⁻¹ [Low], N₂ = 280 kg ha⁻¹ [Medium], and N₃ = 420 kg ha⁻¹ [High]) on growth, gaseous exchange, antioxidant capacity, and N metabolism in ramie (Boehmeria nivea L.) under greenhouse conditions in a completely randomized design (CRD) with three replications. Nitrogen application improved the plant growth, chlorophyll contents, and antioxidant activity of ramie; the maximum shoot fresh biomass (91 g), shoot dry biomass (13.7 g), number of leaves (46.5), and number of stems (6.4) were recorded at medium N rate. However, the growth was reduced under high N rate. Except for intercellular CO₂ concentration, all the other gas exchange parameters were significantly affected by the N levels. Increasing N level improved the activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT), and enhanced the chlorophyll and soluble protein contents in ramie leaves. Thus, N fertilizer at medium rate is relatively more effective in the growth of ramie and biomass production.

中文翻译：

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氮肥作用下麻的形态生理特性，抗氧化能力和氮代谢

最佳施肥是农业可持续发展的挑战之一。了解植物对可用养分的生理和生化反应对于优化作物管理方法很重要。本研究调查了不同水平的氮肥的影响（N ₀  = 0 kg ha ^-1 [对照]，N ₁  = 140 kg ha ^-1 [低]，N ₂  = 280 kg ha ^-1 [中]，N ₃  = 420 kg ha ^-1 [High]）对麻（Boehmeria nivea）的生长，气体交换，抗氧化能力和氮代谢的影响L.）在温室条件下以完全随机设计（CRD）进行三次重复。施氮可以改善of麻的生长，叶绿素含量和抗氧化活性。以中N速率记录最大嫩枝新鲜生物量（91 g），嫩枝干燥生物量（13.7 g），叶数（46.5）和茎数（6.4）。但是，在高氮水平下生长减少。细胞间CO ₂除外浓度，所有其他气体交换参数均受氮水平的显着影响。氮水平的提高改善了nitrate麻叶片中硝酸还原酶（NR），谷氨酰胺合成酶（GS）和谷氨酸合成酶（GOGAT）的活性，并增强了叶绿素和可溶性蛋白质的含量。因此，中等速率的氮肥在of麻和生物量生产方面相对更有效。