中文摘要：

采用分根装置，对均匀灌水、固定灌水和交替灌水3种方式下，于1／2根区设施（^15NH4）2SO4的处理；另1／2根区施人等量的（^14NH4）2SO4，研究玉米不同根区氮素的吸收与分配特征。结果表明，处理15、20、40d时，玉米累积^15N肥料氮量表现为，固定灌水下^15N施在灌水区分别是非灌水区的2．37、2．95和3．41倍；交替灌水下^15N施在先灌水区是后灌水区的1．57、1．08和1．06倍。作物自不同根区土壤或肥料吸收氮素占总吸氮量的百分数表明，交替灌水时，不同根区有同等贡献；固定灌水时，作物吸收的氮素绝大部分来自灌水区。根系的氮素吸收速率和根长均表现为，交替灌水两根区趋于相同；固定灌水的非灌水区明显小于灌水区，表明吸收速率和根长对作物吸收氮素都有重要作用。处理40d时，玉米各部分累积^15N肥料氮占根区总吸收量百分数为地上部：均匀灌水〉交替灌水〉固定灌水；^14N区根系：^15N施在固定灌水的非灌水区〉其他4个处理；^15N区根系：^15N施在固定灌水的灌水区〉固定灌水的非灌水区和交替灌水任一根区〉均匀灌水。说明局部供水使根系的氮素分配明显增多，地上部减少；两种局部灌水所不同的是，固定灌水时，氮素向灌水区根系的分配大于非灌水区；交替灌水时，两根区相近。

英文摘要：

Effects of partial root-zone irrigation on uptake and allocation of nitrogen from different root zones of maize grown in split-root containers were studied. Maize was irrigated on both halves of the container （conventional irrigation, C）, on one side only （fixed partial root-zone irrigation, F）, or alternatively on both sides （alternative partial root-zone irrigation, A）. Isotope-labled ^15N - （NH4）2SO4 was applied to one half of the pot with （^14NH4）2SO4 to the other half so that N inflow could be tracked. Results showed that in the day 15, 20, 40, the ratios of N uptake from ^15N- fertilizer applied in the irrigated root zone（Fw）to that from the non-irrigated zone （Fd） of F treatment were 2.37, 2.95 and 3.41, respectively. For A treatment, the ratios of N uptake from ^15N - fertilizer applied in the early irrigated zone（Ae）to that from the late irrigated zone（Al） were 1.57, 1.08 and 1.06, respectively. The percentages of plant N absorbed from soil or fertilizer in different root zones to total N uptake for three irrigation methods also indicated that the amount of N absorp- tion from two root zones of A treatment was equal whereas for F treatment, the N accumulation in plant was mainly from the irrigated root zone. Considering the fact that root N inflow and root length in the irrigated zone were larger than those of the non-irrigated zone for F treatment, it could be concluded that both of root length and N absorption capacity con- tribute to plant N uptake largely. At 40 day, the percentage of ^15N - fertilizer N allocation in shoot to total accumulation for A treatment was higher than that for F treatment but lower than that for C. The ^15N allocation percentage of the subroot supplied with ^14N - fertilizer was higher for Fd than for the others. The ^15N allocation percentage of the subroot supplied with ^15N - fertilizer was higher for Fd, Al and Ae than for C treatment but lower than for Fw. Our results suggest that partial root-zone irrigation increased N allocation in