不同氮效率小麦品种氮素吸收和物质生产特性

氮条件（N-）下，不同氮效率小麦品种的籽粒产量和氮效率以氮高效品种（H）最高，中效（M）次之，低效（L）最低；H具有较多的单位面积穗数且与N-下籽粒产量和氮效率显著相关，表明单位面积穗数的多少对氮胁迫条件下小麦籽粒产量和氮效率具有重要影响。不同氮效率品种的植株全氮含量（TN）无显著差异。不同生育时期的植株氮累积量（AA）在抽穗期和成熟期以H最大，M次之，L最低，表明生育中后期N-下的植株氮素吸收能力是氮胁迫条件下籽粒产量和氮效率的重要影响因素。不同生育时期的株高、群体茎数、叶面积指数（LAI）和群体干物重（PDW）值；各生育阶段群体生长率（CGR）、净同化率（NAR）和光合势（Pp）；各生育时期的叶片NO3-含量和硝酸还原酶（NR）活性均以H最大，M次之，L最低。叶片亚硝酸还原酶（NIR）)活性和谷氨酰胺合成酶（GS）活性在供试不同氮效率品种之间的差异较小。研究表明，N-下较强的氮素吸收能力和较好的植株生长特性是氮胁迫条件下供试氮高效小麦品种获得高氮效率特征的重要基础。在丰氮条件（N+）下，供试不同氮效率品种的籽粒产量、氮效率、植株氮素吸收和物质生产特性与N-下的表现规律不尽相同。

Characterization of Nitrogen Uptake and Dry Matter Production in Wheat Varieties with Different N Efficiency

Under deficient-N condition, the yield and nitrogen use efficiency were all the highest in the wheat varieties with high-N efficiency (H), then in the varieties with mid-N efficiency (M), and the lowest in the varieties with low-N efficiency among all tested varieties (L). H also had the highest spike number per planting area and correlated with the grain yield and N efficiency significantly, indicating the spike number per planting area has important effects on yield and N efficiency of wheat varieties under deficient-N condition. There were no obvious differences in total nitrogen concentration of plant among the tested varieties. At spiking stage and maturity stage, the accumulative nitrogen amount of plant was the highest in H, then in M, and the lowest in L, showing that the nitrogen absorption capability of plant at mid- growth to late- growth stage has important influence on the grain yield and N efficiency under deficient-N condition. The plant height, stem number of population, leaf area index (LAI), dry weight of population (PDW), NO3- content and nitrate reductase (NR) activity of leaf at each growth spring stage were all the highest in H, then in M and the lowest in L. So was the canopy growth rate (CGR), net assimilation rate (NAR) and photosynthetic potential (Pp) at each spring growth phase. There were little differences on nitrite reductase (NIR) activity and glutamine synthetase (GS) activity among tested varieties. The study indicated that it is the important physiological factor for the high-N efficiency variety to have a higher absorption capability of nitrogen and better growth and development traits of plant. Under sufficient-N condition, it was not always the same on yield, nitrogen use efficiency, nitrogen uptake and day matter production as those under deficient-N condition.