关键词: 苎麻[Boehmeria nivea (L.) Gaudich.], 施氮模式, 氮素利用, 纤维产量, 氮代谢酶

Abstract: The effects of different nitrogen application patterns on nitrogen utilization efficiency, fiber yield and nitrogen metabolism-related enzyme activities of ramie [Boehmeria nivea (L.) Gaudich.] were investigated by setting different basal fertilizer dosages and basal-topdressing ratios (ratios of basal fertilizer to topdressing fertilizer) of nitrogen fertilizer. The results showed that the N_1∶2 treatment (300 kg/hm² basal fertilizer with a basal-to-topdressing ratio of 1∶2) achieved the highest physiological nitrogen use efficiency. In terms of leaf development, the comprehensive growth index of the N_2∶1 treatment (600 kg/hm² basal fertilizer with a basal-topdressing ratio of 2∶1 ) was superior. The fiber yield of the N_2∶3 treatment (600 kg/hm² basal fertilizer with a basal-topdressing ratio of 2∶3) was the highest, which was 62.4% higher than that of the N_0∶0 treatment (CK,no fertilizer), and the effectiveness of the strategy of “stable base fertilizer, strong topdressing” was verified. Although the N_3∶3 treatment (900 kg/hm² basal fertilizer with a basal-topdressing ratio of 3∶3 ) had better morphological indexes such as stem diameter and biomass, the partial factor productivity of nitrogen fertilizer was the lowest, indicating that excessive nitrogen input caused luxury absorption, resulting in a decline in resource conversion efficiency. The results of enzyme activity showed that the N₂ group (medium basal fertilizer group, 600 kg/hm²) established an oxidative stress buffering system by maintaining high activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) while reducing malondialdehyde （MDA） content. Although the N₃ group (high basal fertilizer group, 900 kg/hm²) exhibited the highest glutamate synthase（GOGAT） activity, its insufficient nitrate reductase（NR） activity constrained the nitrogen assimilation flux. Collectively, these findings indicated that medium basal fertilization (600 kg/hm²) supplemented with topdressing optimized ramie production.

Key words: ramie[Boehmeria nivea (L.) Gaudich.], nitrogen application patterns, nitrogen utilization, fiber yield, nitrogen metabolism enzyme