Pedosphere 12(3): 207--218, 2002
ISSN 1002-0160/CN 32-1315/P
©2002 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Effects of atmospheric CO2 enrichment, applied nitrogen and soil moisture on dry matter accumulation and nitrogen uptake in spring wheat
LI Fu-Sheng1 and KANG Shao-Zhong2
1 Agricultural College, Guangxi University, Nanning 530005 (China)
2 Key Laboratory of Agricultural Soil & Water Engineering in the Arid and Semiarid Areas, Ministry of Education, Northwest Sci-Tec University of Agriculture and Forestry, Shaanxi 712100 (China)
ABSTRACT
      Spring wheat (Triticum aestivum L. cv. Dingxi No. 8654) was treated with two concentrations of atmospheric CO2 (350 and 700 μmol mol-1), two levels of soil moisture (well-watered and drought) and five rates of nitrogen fertilizer (0, 50, 100, 150, and 200 mg kg-1 soil) to study the atmospheric CO2 concentration effect on dry matter accumulation and N uptake of spring wheat. The effects of CO2 enrichment on the shoot and total mass depended largely on soil nitrogen level, and the shoot and total mass increased significantly in the moderate to high N treatments but did not increase significantly in the low N treatment. Enriched CO2 concentration did not increase more shoot and total mass in the drought treatment than in the well-watered treatment. Thus, elevated CO2 did not ameliorate the depressive effects of drought and nitrogen stress. In addition, root mass decreased slightly and root/shoot ratio decreased significantly due to CO2 enrichment in no N treatment under well-watered condition. Enriched CO2 decreased shoot N content and shoot and total N uptake; but it reduced root N content and uptake slightly. Shoot critical N concentration was lower for spring wheat grown at 700 μmol mol-1 CO2 than at 350 μmol mol-1 CO2 in both well-watered and drought treatments. The critical N concentrations were 16 and 19 g kg-1 for the well-watered treatment and drought treatment at elevated CO2 and 21 and 26 g kg-1 at ambient CO2, respectively. The reductions in the movement of nutrients to the plant roots through mass flow due to the enhancement in WUE (water use efficiency) and the increase in N use efficiency at elevated CO2 could elucidate the reduction of shoot and root N concentrations.
Key Words:  CO2 enrichment, critical N concentration, dry matter, nitrogen uptake, soil moisture
Citation: Li, F. S. and Kang, S. Z. 2002. Effects of atmospheric CO2 enrichment, applied nitrogen and soil moisture on dry matter accumulation and nitrogen uptake in spring wheat. Pedosphere. 12(3): 207-218.
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