Characterization of nitrogen uptake and dry matter production in wheat varieties with different N efficiency

Chinese. 通过研究不同氮效率小麦的氮素吸收和物质生产特性，阐明氮高效小麦品种高效吸收氮素的生物学基础。以具有典型特征的不同氮效率小麦品种为材料，研究丰、缺氮条件下的籽粒产量、氮效率、氮素吸收特性和氮素吸收同化关键酶活性。缺氮条件下，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籽粒产量和氮效率显著相关；不同生育时期的植株氮累积量在抽穗期和成熟期以H最大，M次之，L最低；不同生育时期株高、群体茎数、叶面积指数、群体干物重、叶片NO3-含量和硝酸还原酶活性以及各生育阶段群体生长率、净同化率和光合势均以H最大，M次之，L最低；叶片亚硝酸还原酶活性和谷氨酰胺合成酶活性在供试不同氮效率品种之间差异较小。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的生物学基础。在丰氮条件下，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缺氮条件下的表现规律不尽相同。

English. In order to elucidate the biological basis with high nitrogen uptake capacity in the wheat varieties, the characterization of nitrogen uptake and dry matter production in wheat varieties with different N efficiency were studied. Yield, nitrogen efficiency, characterization of nitrogen uptake and key enzyme activity of nitrogen assimilation were studied in wheat varieties with different nitrogen efficiencies. Under deficient-N conditions, the yield and nitrogen use efficiencies were all highest in the wheat varieties with high-N efficiency (H), then in the varieties with mid-N efficiency (M), and 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. At spiking stage and maturity stage, the accumulative nitrogen amount was highest in H, then in M, and lowest in L. The plant height, stem number of population, leaf area index, dry weight of population, NO3- content and nitrate reductase activity in the leaf at each spring growth stage were all highest in H, then in M and lowest in L. So were the canopy growth rate, net assimilation rate and photosynthetic potential at each spring growth phase. There were little differences on nitrite reductase activity and glutamine synthetase activity among tested varieties. This study indicated that the high nitrogen efficiency characterization in wheat varieties was tightly related to higher absorption and utilization capability of nitrogen, and better growth and development traits of plants under deficient-N condition. Under sufficient-N conditions, it was not always the same yield, nitrogen use efficiency, nitrogen uptake and dry matter production as those under deficient-N condition.