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林业科学 ›› 2022, Vol. 58 ›› Issue (6): 23-32.doi: 10.11707/j.1001-7488.20220603

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连续2年氮添加对中金杨幼苗叶光合特性与碳氮分配的影响

尚佳州1,高钿惠1,王卫锋1,*,周新军2,宗毓铮3   

  1. 1. 山西农业大学林学院 晋中 030801
    2. 山西省桑干河杨树丰产林实验局科技服务中心 朔州 038300
    3. 山西农业大学农学院 晋中 030801
  • 收稿日期:2021-11-10 出版日期:2022-06-25 发布日期:2022-09-24
  • 通讯作者: 王卫锋
  • 基金资助:
    国家自然科学基金项目(31400527);山西省应用基础研究项目(201701D221190);山西农业大学青年拔尖创新人才支持计划(BJRC201602)

Effect of Nitrogen Addition for Two Consecutive Years on Photosynthetic Characteristics, Carbon and Nitrogen Distribution of Populus × euramericana 'Zhongjin7' Seedlings

Jiazhou Shang1,Tianhui Gao1,Weifeng Wang1,*,Xinjun Zhou2,Yuzheng Zong3   

  1. 1. College of Forestry, Shanxi Agricultural University Jinzhong 030801
    2. Science and Technology Service Center, Sangganhe Test Bureau of High-yield Poplar Plantation of Shanxi Shuozhou 038300
    3. College of Agriculture, Shanxi Agricultural University Jinzhong 030801
  • Received:2021-11-10 Online:2022-06-25 Published:2022-09-24
  • Contact: Weifeng Wang

摘要:

目的: 研究不同强度氮添加对杨树叶片光合特性、各器官生物量、非结构性碳水化合物积累和分配的影响, 探讨过量氮添加下杨树的生理生态过程响应机制, 为未来氮沉降条件下杨树人工林精准施肥提供理论依据。方法: 以盆栽黑青杂交杨中'金杨7号’扦插苗为材料, 以NH4NO3为氮源, 设置CK(0 g·plant-1 a-1)、N3(3 g·plant-1 a-1)、N6(6 g·plant-1 a-1)、N9(9 g·plant-1 a-1)4个氮添加梯度, 连续2年测定氮添加后其功能叶光合特性、器官间生物量、碳同化物和氮分配的变化, 并分析叶片光合特性和同化物分配的调控过程。结果: 1) 连续2年氮添加后, 中金杨幼苗叶氮和叶绿素含量增加, 气孔变小变密, 瞬时水分利用效率显著提高, 光合氮利用效率显著降低。2) 中低剂量氮添加下顶梢叶片光合作用显著受到库限制, 侧枝叶净光合速率明显高于对照; 高氮处理下叶净光合速率和淀粉含量显著减小, 荧光量子产量和电子传递速率显著增加, 表明叶片中光呼吸等过程为硝酸还原过程提供大量能量。3) 氮添加持续促进侧枝生长, 顶端优势弱化, 但高氮处理下因叶片光合作用的源限制, 主茎淀粉含量和生物量积累显著降低, 根干质量和生物量分配比例与中低氮处理无显著差异; 高氮处理下各器官生长和碳氮分配结果表明, 生长素合成和运输减弱可能在碳氮关系协调过程中起到重要作用。结论: 中低剂量氮添加下中金杨侧枝叶片光合能力显著增强并促进植株生长, 叶片光合作用处于库限制; 高氮下叶片光合作用可能受到氮同化过程抑制, 顶端优势减弱, 植株生物量积累处于源限制。

关键词: 中金杨, 氮添加, 光合特性, 非结构性碳, 水化合物, 碳氮分配

Abstract:

Objective: Excessive nitrogen addition can restrain the leaf photosynthesis and growth of woody plants. However, the underlying ecophysiological mechanism is still not very clear, which is important for precision fertilization to seedlings and plantation. Poplar (Populus spp.) is an important afforestation species and biological model tree. This study aims to investigate the photosynthetic and chlorophyll fluorescence characteristics, nonstructural carbohydrate (NSC) and nitrogen distribution of hybrid poplar seedlings under nitrogen addition for 2 consecutive years, in order to reveal the ecophysiological mechanism of trees in responding and adapting to nitrogen addition. Method: In this study, the potted cuttings of P. × euramericana 'Zhongjin7' were used as experimental materials, NH4NO3 was used as nitrogen source and 4 gradients (CK: 0 g·plant-1a-1, N3: 3 g·plant-1a-1, N6: 6 g·plant-1a-1, N9: 9 g·plant-1a-1) were set. After nitrogen addition for 2 years, changes of leaf photosynthetic characteristics, organ biomass accumulation, non-structural carbohydrate storage and distribution were investigated. Result: After nitrogen addition for consecutive 2 years, the nitrogen content and chlorophyll content in leaves and roots significantly increased, stomata became smaller but higher density, transient water use efficiency remarkably increased, but photosynthetic nitrogen use efficiency continuously decreased. Under moderate and low dose nitrogen addition, the net photosynthesis (Pn) of leaves on top twig was suppressed by sink and high carbohydrate feedback inhibition. But the Pn of lateral branch leaves was higher than that of the control. Under high nitrogen addition, Pn and starch content were significantly decreased, but with actual fluorescent quantum yield and electron transport rate increased significantly, suggesting that photorespiration and other processes supplied large amount energy for nitrate reduction and assimilation. Nitrogen addition continued to promote lateral branch growth and weaken the apical dominance. Under N9 conditions, the starch content in main stem decreased with a lower biomass, which maybe due to the source inhibition of Pn. The root drymass and biomass distribution percentage of N9 were no significantly different with those of N3 and N6. The results of organ growth, and carbon and nitrogen distribution implied that the decline of aux in synthesis and transport might play an important role in whole plant carbon and nitrogen relationships under excessive nitrogen addition. Conclusion: Nitrogen addition with moderate and low doses can significantly enhance carbon assimilation of leaves on the lateral branch and increase plant growth of whole poplar seedlings, with a sink limit on leaf net photosynthesis. But leaf photosynthesis may be inhibited by nitrogen assimilation under high dose nitrogen addition, with a declined apical dominance. And whole plant biomass accumulation could be restricted by source.

Key words: Populus×euramericana'Zhongjin7', nitrogen addition, photosynthetic traits, nonstructural carbohydrate, carbon and nitrogen distribution,  

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