CO_2浓度、氮和土壤水分对春小麦养分利用效率的影响

Effects of CO_2 Enrichment, Nitrogen and Water on Soil Moisture Spring Wheat Nutrient Use Efficiency

试验设 2种CO2 浓度水平 (35 0和 70 0 μmol/mol) ,2种土壤水分处理 (湿润、干旱 )和 5种氮肥施用水平(0、5 0、10 0、15 0和 2 0 0mg/kg土 )。结果表明 ,CO2 浓度升高降低春小麦的氮肥表观利用率 ,但增加氮、磷、钾利用效率。氮肥表观利用率和氮、钾利用效率会因土壤水分不足而降低 ,而磷利用效率则因水分不足而增加 ,氮、钾利用效率随着氮肥用量增加而降低。此外 ,春小麦氮利用效率与根冠比率呈直线关系 ,而与冠层水分利用效率呈显著负相关。

Spring wheat (Triticum aestivum L. cv. Dingxi No. 8654) was treated with two concentrations of atmospheric CO 2 (350 and 700 μmol/mol), two levels of soil moisture (well-watered and drought) and five applying rates of nitrogen fertilizer (0, 50, 100, 150, 200 mg/kg soil). Results showed elevated CO 2 concentration reduced the apparent recovery fraction of N applied by spring wheat, but increased the N, P and K use efficiency. Soil water limitation reduced N apparent recovery fraction and N and K use efficiency, but increased P use efficiency. And N and K use efficiency decreased with increasing N applied. In addition, N use efficiency was proportional to root/ shoot ratio, but negatively proportional to canopy water use efficiency significantly.