小麦产量对中后期氮素胁迫的响应及品种间差异

生育中后期土壤供氮不足是导致小麦减产的重要原因之一。2015—2017年连续2个生长季,选择人工合成六倍体小麦衍生品种(synthetic hexaploid wheat-derived cultivar, SDC)和非人工合成小麦衍生品种(Non-synthetic hexaploid wheat-derived cultivar, NSC)各3个,设置2个施氮水平,研究其产量及相关生理参数对中后期氮素胁迫的响应。SDC包括川麦42、川麦104和绵麦367, NSC包括绵麦37、川农16和川麦30。2个施氮水平为正常施氮处理(Nn, 150kg N hm~(–2),底肥40%、拔节肥60%)和中后期氮胁迫处理(Ns, 60 kg N hm~(–2),全部作底肥)。结果表明,氮胁迫下,两类品种产量均值降幅接近(SDC 19.6%, NSC 20.4%),但正常供氮下SDC产量高于NSC (高14.4%),其氮胁迫下的产量也较高(高15.9%)。氮胁迫下, SDC的生物产量、单位面积粒数均高于NSC。开花期,两类品种在2个氮素水平下的叶面积指数(LAI)接近,但在灌浆中后期的降幅SDC小于NSC,花后22d,SDC在高、低施氮水平下的LAI较NSC分别高25.1%和16.0%。开花灌浆阶段, 2个施氮水平下SDC旗叶和倒二叶SPAD始终高于NSC,氮胁迫下二者的差距增大。两类品种的净光合速率(NPR)和群体光合速率(CAP)的差异也主要出现在灌浆中后期,氮胁迫下SDC以上2个参数较NSC均有优势。氮胁迫下,花后功能叶片的硝态氮、铵态氮、可溶性糖含量SDC也高于NSC。SDC较NSC有更高的氮素利用效率(NUtE),氮胁迫下,二者NUtE的差距增加。以上结果表明,低氮胁迫下SDC的生产力高于NSC,这与其较高的库容、较长叶片功能期有关。

Response of yield and associated physiological characteristics for different wheat cultivars to nitrogen stress at mid-late growth stage

Soil nitrogen (N) deficiency at mid-late growth stage is one of the serious factors leading to lowered grain yield of wheat. The high yield potential of synthetic hexaploid wheat-derived cultivar (SDC) has been well documented, however, its responses to N deficiency at mid-late growth stage need further study. Six cultivars were grown under two fertilizer-N applied conditions over two consecutive growing seasons (2015-2017). The cultivars consisted of three typical SDC (Chuanmai 42, Chuanmai 104 and Mianmai 367) and three non-synthetic hexaploid wheat-derived cultivar (NSC; Mianmai 37, Chuannong 16, and Chuanmai 30). Two N treatments consisted of normal N application (Nn, 150 kg hm ^-2, basal fertilizer 40%, top dressing 60%) and N stress (Ns, 60 kg hm ^-2, basal fertilizer only), and grain yield and associated physiological traits of these wheat cultivars in response to N deficiency at mid-late growth stage were studied. It turned out that the mean yield reduction of SDC (19.6%) and NSC (20.4%) was close under N stress, while SDC showed 14.4% (Nn) and 15.9% (Ns) advantages on yield than NSC at both N treatments. Besides, the biomass and grain number per unit area of SDC were higher than those of NSC. At anthesis, SDC and NSC had roughly the same leaf area index (LAI) values, whereas the LAI decline in SDC was less than that in NSC at mid-late grain-filling stage. Compared with NSC, the LAI of SDC was 25.1% (Nn) and 16.0% (Ns) higher at 22 days after anthesis, respectively. The SPAD values of flag and penultimate leaves in SDC were always higher than those in NSC at both N treatments during grain filling period, and the gap between them was increased under N stress. The differences in net photosynthetic rate (NPR) and canopy photosynthetic rate (CAP) between the two types of wheat also mainly appeared at mid-late grain-filling stage, and SDC still had advantages compared with NSC under Ns. In addition, the nitrate N, ammonium N and soluble sugar content in flag and penultimate leaves in SDC were higher than those in NSC under N stress condition. At last, SDC had higher N utilization efficiency (NUtE) than NSC, which difference between SDC and NSC was further increased by N stress. Overall, the above results indicate that the productivity of SDC is stronger than that of NSC at low N condition, which might be related to the higher sink capacity and longer leaf function period in SDC.