Page 64 - 《广西植物》2026年第6期
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6 期           胡家雪等: 不同生态型硬叶兜兰的氮素利用效率差异比较及其碳氮分配策略                                            9 7 9

                                   1            1ꎬ3        1              1∗                   1
                        HU Jiaxue ꎬ WU Qian ꎬ LI Yin ꎬ LI Zongyan ꎬ RUAN Yuehong ꎬ
                                                           1                 2
                                           YANG Jianmin ꎬ NIAN Yaoping
                  ( 1. College of Landscape and Horticultureꎬ Southwest Forestry Universityꎬ Kunming 650224ꎬ Chinaꎻ 2. College of Soil and Water
                               Conservationꎬ Southwest Forestry Universityꎬ Kunming 650224ꎬ Chinaꎻ 3. Yiliang County
                                        State ̄Owned Garden Forest Farmꎬ Kunming 652100ꎬ China )

                 Abstract: To reveal the nitrogen adaptation mechanisms of different Paphiopedilum micranthum ecotypes in karst
                 habitatsꎬ this study focused on three ecotypes (lithophytic typeꎬ scrub terrestrial typeꎬ and understory terrestrial type)
                 co ̄occurring in a limestone area in southeastern Yunnan. We aimed to compare their nitrogen uptake and utilization
                 efficiencies and elucidate their ecological adaptation strategies from the perspective of carbon ̄nitrogen allocation. By
                 measuring soil available nitrogen contentꎬ and analyzing plant N phenotypes along with the activities of key N metabolism
                 enzymes. We compared inter ̄ecotype differences in N accumulation and use efficiencyꎬ followed by correlation analysis
                 of influencing factors. The results were as follows: (1) No significant difference was observed in nitrogen uptake
                 efficiency ( NUpE)ꎬ while nitrogen use efficiency ( NUE) differed significantly among ecotypes ( P < 0. 05). The
                                                ̄1                                               ̄1
                 lithophytic type [(2.83 ± 0. 14) gmg ] and the understory terrestrial type [(2.83 ± 0.05) gmg ] exhibited
                                                                          ̄1
                 significantly higher NUE than the scrub terrestrial type [(2.64±0.22) gmg ]. (2) Divergent adaptive characteristics
                 were formed: the understory terrestrial type had significantly greater total root length [(64.80±9.86) cm] and root ̄to ̄
                 shoot ratio (0.95±0.22) than the lithophytic type [total root length: (50.26±17.50) cmꎻ root ̄to ̄shoot ratio: 0.72±
                 0.17]. In contrastꎬ the lithophytic type displayed the highest nitrogen uptake per unit root lengthꎬ significantly
                 surpassing the understory terrestrial type (P<0.05). The scrub terrestrial type demonstrated a strong nitrate assimilation
                                                                             ̄1   ̄1
                 capacityꎬ possessing the highest nitrate reductase activity [(49.37±1.08) μgg h ] and leaf N concentration. (3)
                 Carbon ̄nitrogen allocation strategies differed markedly: the lithophytic type had the highest whole ̄plant carbon ̄to ̄
                 nitrogen ratio (C/ N)ꎬ whereas the scrub terrestrial type exhibited the greatest C and N accumulations but the lowest
                 C/ N. The understory terrestrial type generally displayed intermediate values for these traits. (4) The correlation analysis
                 showed thatꎬ nitrogen use efficiency was significantly positively correlated with total root lengthꎬ root carbon
                 accumulationꎬ and leaf C/ Nꎬ and significantly negatively correlated with soil ammonium nitrogen content. In conclusionꎬ
                 the different ecotypes develop complementary nitrogen adaptation mechanisms by regulating root architecture and carbon ̄
                 nitrogen allocation. The lithophytic type achieved the highest nitrogen use efficiency through more nitrogen uptake per
                 unit root length and a resource allocation strategy characterized by a higher C/ N. By comparing the differences in
                 nitrogen uptake/ use efficiency and N metabolism physiology among ecotypesꎬ this study elucidates their ecological
                 adaptation mechanisms from the perspective of carbon ̄nitrogen allocationꎬ and provides a theoretical basis for the
                 scientific conservation and cultivation of this species.
                 Key words: Paphiopedilum micranthumꎬ karst ecotypeꎬ nitrogen use efficiency (NUE)ꎬ ecological adaptationꎬ carbon ̄
                 nitrogen allocation


                植物在贫氮生境中的氮素利用策略是养分生                            数(符裕红等ꎬ 2020ꎻChang et al.ꎬ 2024)ꎮ 植物氮
            态研究的热点问题ꎬ对于揭示植物的环境适应性                              素利用效率的高低受到土壤氮供应、生境条件以
            与进化机制具有重要的理论意义ꎮ 植物对氮素的                             及植物自身遗传特性与表型可塑性的复杂网络调
            利用效率( nitrogen use efficiencyꎬ NUE) 是一个综           控 ( Xu & Takahashiꎬ 2020ꎻ Govindasamy et al.ꎬ
            合性的功能性状ꎬ反映了其从获取到利用氮资源                              2023)ꎮ 不同物种乃至同一物种的不同生态型或
            的整体效能(Wang et al.ꎬ 2019ꎻWani et al.ꎬ 2021ꎻ         基因型ꎬ在根系构型、氮吸收动力学偏好以及氮同
            Yan et al.ꎬ 2023)ꎮ 在实际研究中ꎬ植株不同器官                   化关键酶活性上存在差异ꎬ这些差异共同塑造了
            的氮含量、氮积累量以及碳氮比( C / N) 等指标ꎬ常                       其独特的氮素利用效率( Duan et al.ꎬ 2023ꎻWang
            被用作评估其氮素利用策略与效率的重要代理参                              et al.ꎬ 2023ꎻTang et al.ꎬ 2023)ꎮ 例如ꎬ高原生态
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