开放式空气二氧化碳浓度增高对小麦氮素吸收利用的影响

2001—2003年，利用我国唯一的农田开放式空气CO₂浓度增高 (free-air carbon dioxide enrichment，FACE) 技术平台，研究了FACE条件下冬小麦宁麦9号不同生育期N含量、吸收、分配和N效率的响应.结果表明：与对照相比，FACE处理使不同生育时期植株含N率显著降低，降幅达4.4%～13.4%；不同生育时期吸N量显著增加(7.4%～25.4%)，生育中期的增幅明显大于生育前、后期；不同生育时期茎鞘的N积累能力相对增强，叶片N积累能力相对减弱，而对麦穗N积累能力的影响因生育进程而异；FACE处理使小麦不同生育时期N物质生产效率(5.5%～10.3%)、成熟期N收获指数(16.3%)和N籽粒生产效率(9.3%)均显著或极显著增加；增施N肥，使小麦不同生育时期N含量和吸收量呈增加趋势，使N效率呈下降趋势，而对N在各器官中分配的影响较小.

Effects of free-air CO2 enrichment on nitrogen uptake and utilization of wheat

In this paper, the effects of free-air CO2 enrichment (FACE) and its interaction with nitrogen supply on the nitrogen content, uptake, allocation, and use efficiency of winter wheat variety Ningmai 9 at its different growth stages were studied in 2001-2003. The results showed that under FACE treatment, the nitrogen content in wheat plant sampled at different growth stages all decreased significantly, with an average decrement of 4.4% to 13.4% compared with the control. The nitrogen accumulation under FACE increased significantly (9.2% -32.3%), and the increasing rate was larger at middle growth stage than at early and late growth stages. Nitrogen fraction was higher in stem, but lower in leaf. As for spike, the accumulation of nitrogen depended on the growth stage. FACE resulted in a significant increase (5.5% -10.3%) of nitrogen use efficiency for biomass production at all growth stages, of nitrogen harvest index (16.3%) at maturing stage, and of nitrogen use efficiency (9.3%) for grain yield. Nitrogen application increased the nitrogen content of wheat plant and its N uptake at all growth stages, decreased the nitrogen use efficiency, but had less effect on the nitrogen allocation in different organs.