Effects of Atmospheric CO2 Enrichment, Applied Nitrogen and Soil Moisture on Dry Matter Accumulation and Nitrogen Uptake in Spring Wheat

摘要

Spring wheat (Triticum aestivum L. cv. Dingxi No. 8654) was treated with two concentrations of atmospheric COz (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 CO2concentration 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.

机译：用两种浓度的大气COz（350和700μmolmol-1），两种水平的土壤水分（水肥和干旱）和五种氮肥处理春小麦（定西小麦Trisum aestivum L. cv。Dingxi No. 8654）。（0、50、100、150和200 mg kg-1土壤）研究大气CO2浓度对春小麦干物质积累和氮吸收的影响。 CO 2富集对枝条和总质量的影响在很大程度上取决于土壤氮水平，在中至高氮处理下，枝条和总质量显着增加，而在低氮处理中，枝条和总质量没有显着增加。与干旱灌溉相比，干旱处理中增加的二氧化碳浓度没有增加更多的芽和总质量。因此，升高的CO 2并没有减轻干旱和氮胁迫的抑制作用。此外，在水分充足的条件下，在不进行氮素处理的情况下，由于CO2富集，根质量略有下降，根/茎比也显着下降。富集的二氧化碳减少了地上部的氮含量以及地上部和总氮的吸收。但它会略微降低根系N含量和吸收。在浇水和干旱处理下，以700μmolmol-1 CO2生长的春小麦的苗期临界氮浓度均低于350μmolmol-1 CO2。在高CO2浓度下进行充分灌溉和干旱处理时，临界N浓度分别为16和19 g kg-1，在环境CO2下分别为21和26 g kg-1。由于WUE（水分利用效率）的提高，营养物质通过质量流向植物根部运动的减少，以及在较高的CO2浓度下氮素利用效率的提高，可以说明芽和根系N浓度的降低。

Effects of Atmospheric CO2 Enrichment, Applied Nitrogen and Soil Moisture on Dry Matter Accumulation and Nitrogen Uptake in Spring Wheat

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