中文摘要：

2005、2006年利用我国惟一的农田开放式空气CO2浓度增高（FACE）研究平台，设计施N量为125kg·hm^-2（LN）、250kg·hm^-2（NN）处理，研究大气CO2浓度比对照高200umol·mol^-1的FACE处理对三系杂交籼稻汕优63根系活性的影响。结果表明：（1）FACE处理使汕优63不同生育时期单位干质量根系的总吸收面积、活跃吸收面积、α-萘胺氧化量等根系活性指标均极显著小于对照。由于FACE处理促进汕优63根系发生量的大幅度增加，因此分蘖期、拔节期其单穴根系活性与对照多无明显差异，到抽穗期FACE处理单穴根系活性显著大于对照；（2）拔节期、抽穗期汕优63每穴的不定根数、不定根总长度、根系体积、根干质量与单位干质量根系活性的关系密切，根量越大单位于质量根系活性越低；（3）不同生育时期汕优63植株含氮率与单位干质量的根系活性多呈正相关，植株碳氮比与单位干质量的根系活性多呈负相关；（4）FACE处理汕优63根系生长量大、植株含氮率低、碳氮比高等可能是造成其单位干质量根系活性低于对照的重要原因。

英文摘要：

In this study, the Chinese unique Free Air CO2 Enrichment [FACE, 200 umol·mol^-1 higher than ambient（AMB）] research platform was used to investigate the effects of FACE on root growth dynamics at different growth stages of three-line indica hybrid rice eultivar Shanyou 63 under two levels of N：low （LN, 125 kg·hm^-2） and normal N （NN, 250 kg·hm^-2）in 2005-2006. Main results showed that： （ 1 ）Compared with AMB, FACE significantly decreased the total absorption area per unit dry weight of root, the active absorption area per unit dry weight of root and the amount of α-NA per unit root dry weight of shanyou 63 at different growth stages. While FACE made larger increment of rice root, which resulted in little effects of FACE on root activity per hole at tillering and jointing stages, but FACE significantly increased root activity per hole at heading stage. （2）Root activity per unit dry weight of root negatively correlated with the number of adventitious roots per plant, total length of adventitious roots per plant, roots volume and dry weight of root at jointing and heading stages. The larger the root productions, the lower the root activity per unit dry weight. （ 3 ）For the most part, root activity per unit dry weight of root positively correlated with N content of rice plant, and negatively correlated with C/N ratio. （4）The larger biomass accumulated, lower N content in rice plant and higher C/N ratio appear to be the primary causes of significant decrement of root activity per unit dry weight of root under FACE condition.