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Reduced mesophyll conductance by cell wall thickening and chloroplasts decreasing driven the decline of photosynthesis under sole NH 4 + supply
  • +2
  • Yiwen Cao,
  • Yonghui Pan,
  • Tianheng Liu,
  • Min Wang,
  • Shiwei Guo
Yiwen Cao
Jiangsu Provincial Key Lab for Organic Solid Waste Utilization National Engineering Research Center for Organic-based Fertilizers Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization Nanjing Agricultural University Weigang 1 Nanjing 210095 China
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Yonghui Pan
Jiangsu Provincial Key Lab for Organic Solid Waste Utilization National Engineering Research Center for Organic-based Fertilizers Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization Nanjing Agricultural University Weigang 1 Nanjing 210095 China
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Tianheng Liu
Jiangsu Provincial Key Lab for Organic Solid Waste Utilization National Engineering Research Center for Organic-based Fertilizers Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization Nanjing Agricultural University Weigang 1 Nanjing 210095 China
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Min Wang
Jiangsu Provincial Key Lab for Organic Solid Waste Utilization National Engineering Research Center for Organic-based Fertilizers Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization Nanjing Agricultural University Weigang 1 Nanjing 210095 China
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Shiwei Guo
Jiangsu Provincial Key Lab for Organic Solid Waste Utilization National Engineering Research Center for Organic-based Fertilizers Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization Nanjing Agricultural University Weigang 1 Nanjing 210095 China

Corresponding Author:[email protected]

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Abstract

The relationship between nitrogen (N) sources and photosynthetic capacity of leaf differs between species. However, the leaf anatomical variabilities related to photosynthesis ( A) of shrubs under different forms of N remain imperfectly known. Here, Lonicera Japonica (a shrub) was grown hydroponically in the presence of three forms of N (sole NH 4 +, 50%/50% NH 4 +/NO 3 and sole NO 3 ). A and photosynthetic N use efficiency significantly decreased under sole NH 4 + supply, in parallel with down-regulated stomatal conductance ( g s), mesophyll conductance ( g m), and electron transfer rate ( J). Up to the total A decline of 41.28% in sole NH 4 + supply (compare with sole NO 3 ), the g m attributed to 60.3% of the total limitations. Besides, the decreased internal air space explained the increase of gas-phase resistance, and the increased liquid-phase resistance in sole NH 4 + supply was ascribed to the thicker cell wall thickness ( T cw) and decreased chloroplasts exposed surface area per unit leaf area ( S c/ S). The discrepancy of S c/ S could be interpreted by the altered chloroplasts numbers and the distance between adjacent chloroplasts ( D chl-chl). These results indicate the alteration of T cw and chloroplast numbers were the main causes of the difference in g m in coping with varied N sources.