中文摘要：

设置了5个氮素浓度梯度（N0、N1、N2、N3、N4）、3个PEG （P0、P1、P2）浓度梯度以及2个CO2浓度（370±50μmol·mol－1；700±50μmol·mol－1）水平的盆栽试验，探究了小麦幼苗生长、物质积累与分配以及植株水分条件的变化规律。结果表明：小麦幼苗株高、地上部干重、根干重、生物量以及叶水势的最大值以及高浓度CO2的最大刺激作用均出现在处理N1P0；而根长和根冠比的最大值分别出现在处理N0P0和N1P2，高浓度CO2的最大刺激值也分别出现在处理N0 P0和N1 P2；适宜养分条件下，高浓度CO2能够最大限度地促进小麦幼苗的生长，同时高浓度CO2通过提高小麦幼苗叶水势，一定程度上缓解了低浓度PEG胁迫的不利影响。因此，未来CO2浓度升高将对水肥条件好的小麦产生促进作用，可缓解轻度水分不足的不利影响，而对严重干旱胁迫下小麦的生长作用不明显。

英文摘要：

On the basis of hydroponic experiment ,this pot study included five nitrogen concentration levels （N0、N1、N2、N3、N4 ） ,three PEG concentration levels （P0、P1、P2 ） ,and two CO2 concentrations （370 ± 50 μmol·mol-1 ;700 ± 50 μmol·mol-1 ） .We studied the growth ,dry matter accumulation and distribution ,and water relation of wheat seedlings in different conditions .The results showed that plant height ,shoot dry weight ,root weight ,biomass ,and leaf water potential reached their maximums at N1P0 ,and so were the effects of elevated CO2 concentration .Maximal root length and root to shoot ratio appeared at N0 P0 and N1 P2 respectively .The biggest influence of elevated CO2 arose under the same condition .High CO2 concentration could mostly improve the growth of wheat seedlings at appropriate condition . At the same time ,elevated CO2 could improve leaf water potential of wheat seedlings ,which reduced the negative effects of PEG stress to some extent .Therefore ,elevated CO2 concentration would improve the growth of wheat and remit the＆nbsp;negative effects of mild water stress ,whereas subtle effect might be observed if wheat growth was under severe drought .