中文摘要：

由玉米根为水举起检验潜在的杂种优势，在 F1 混血儿(Hudan 4 ) 的根的水力的性质与它的生来的父母的那些相比(478 并且 Tian 4 ) 在细胞、单个根、整个根的系统层次在下面浇得好并且水赤字条件。房间水力的电导率(Lp c ) 在水赤字下面减少了，但是 F1 的 Lp c 比它的生来的父母与或没有从水赤字的应力的高。在 Lp c 的显著减小被观察跟随 Hg2+ 处理。单个根(静水力学的 Lp sr ) 的静水力学的水力的传导性在二个水处理下面在遗传型之中变化了，与在 F1 最高、在 478 最低。光线的水力的电导率(光线的 Lp sr ) 和三遗传型的轴的水力的传导力(L 斧子) 作为 Lp sr 同样变化了。在水力的参数的变化与根解剖有关。光线的 Lp sr 否定地与外皮宽度的比率被相关到根直径( R 2=0.77 ， P < 0.01 )，而 L 斧子断然与中央木部容器的直径被相关( R 2=0.75 ， P < 0.01 )并且木部容器的代表性的区域( R 2=0.93 ， P < 0.01 )。水力的电导率(Lp wr ) 和整个根的系统的传导力(L wr ) 在二个水处理下面跟随了一样的趋势，与在 F1 的最高的值。结果证明为由 F1 的根的水举起的那杂种优势发生在细胞、单个根、整个根的系统层次在下面浇得好并且水赤字条件。

英文摘要：

To examine the potential heterosis for water uptake by maize roots, the hydraulic properties of roots in the F1 hybrid （Hudan 4） were compared with those of its inbred parents （ 478 and Tian 4） at cellular, single-root and whole-root system levels under well-watered and water-deficit conditions. The cell hydraulic conductivity （Lpc） decreased under water deficit, but the Lpc of the F1 was higher than that of its inbred parents with or without stress from water deficit. Marked reductions in Lpc were observed following Hg2＋ treatment. The hydrostatic hydraulic conductivity of single roots （hydrostatic Lpsr） varied among genotypes under the two water treatments, with the highest in the F1 and the lowest in 478. Radial hydraulic conductivity （radial Lpsr） and axial hydraulic conductance （Lax） of the three genotypes varied similarly as Lpsr. The variations in hydraulic parameters were related to root anatomy. Radial Lpsr was negatively correlated with the ratio of cortex width to root diameter （R2=-0.77, P〈0.01）, whereas Lax was positively correlated with the diameter of the central xylem vessel （R2=0.75, P〈0.01） and the cross-sectional area of xylem vessels （R2=0.93, P〈0.01 ）. Hydraulic conductivity （Lpwr） and conductance （Lwr） of the whole-root system followed the same trend under the two water treatments, with the highest values in the F1. The results demonstrated that heterosis for water uptake by roots of the F1 occurred at cellular, single-root and whole-root system levels under well-watered and water-deficit conditions.