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《Journal of Agro-environmental Science》 2005-05
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Effects of Free-Air CO_2 Enrichment (FACE) on Concentrations of Various N Forms in Rice Tissues

PANG Jing1,2, ZHU Jian-guo1, LIU Gang1(1.State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008, China; 2.Faculty of Resource and Environment,Hubei University,Wuhan 430062, China).  
Effects of Free-air CO2 enrichment (FACE) on concentrations of various N forms in rice tissues at low N (LN 150 kgN·hm-2) and normal N ( NN 250 kgN·hm-2), respectively, were studied under ambient air and elevated atmospheric pCO2 (Ambient+200 μmol·mol-1) by the China FACE (Free-Air CO2 Enrichment). At both N levels, elevated pCO2 led to significant decreases in N concentrations expressed on a dry mass basis in roots, stems, leaves at tillering stage; in stems at heading stage and in leaves, roots at ripening stage, respectively, and 50 %~181.8 % of which was attributed to decreases in protein-N concentrations in these tissues as compared with ambient CO2. Thus, N concentration decreases in rice tissues could be partly accounted for by reductions in protein-N concentration. Accumulation of biomass could also lead to a ‘dilution’ of N and resulted in lower N concentrations in plant tissues as plants had higher dry matter production of stems, ears and roots under elevated pCO2. Furthermore, free amino acid-N concentrations in most tissues declined during the whole growing season due to elevated pCO2, while inorganic N concentrations showed variable responses to elevated pCO2 through time. The decreases in free amino acid-N concentration in plant parts may be caused by the altered capability of synthesizing amino acids in rice roots due to CO2 enrichment and could have negative effect on protein synthesis. More experiments will be necessary to study the relationship between amino acid synthesis in rice roots and protein-N concentration in plant tissues under elevated pCO2.
【Fund】: 国家自然科学基金项目(NSFC-40271061);; 国家自然科学基金重大国际合作研究资助项目(NSFC-40120140814);; 中国科学院重要知识创新重要方向项目(kzcx2-408);; 973项目(CCDMCTE-2002CB412502);973项目(2002CB14003)
【CateGory Index】: S511;
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