不同基因型玉米品种产量和氮素利用效率对减施氮肥的响应

选用氮高效型高产品种是实现玉米高产稳产、节本增效的重要技术途径。以我国玉米生产主推品种郑单958(Zhengdan 958,ZD958)、先玉335(Xianyu 335,XY335)、京科968(Jingke 968,JK968)和京农科728(Jingnongke 728,JNK728)为试验材料,设置0 kg/hm~2(N0)、75 kg/hm~2(N1)、150 kg/hm~2(N2)和225 kg/hm~2(N3)共4个纯氮施用水平,研究并明确不同基因型玉米品种产量和氮素利用效率对减施氮肥的响应特征。结果表明:(1)施用氮肥可显著提高玉米籽粒产量,4个氮肥处理条件下籽粒产量均以京科968为最高,分别较郑单958、先玉335和京农科728平均增产4.1%、7.7%和14.6%。施氮量由纯氮225 kg/hm~2适当减施75kg/hm~2(N3→N2)时,京科968和京农科728减产不显著;而郑单958和先玉335减产显著。(2)不同施氮水平下,品种间的单株生物量、花后干物质积累量和干物质转移率存在显著差异。施氮量由纯氮225 kg/hm~2减为150 kg/hm~2(N3→N2)时,京科968和京农科728单株生物量降低,但差异不显著,而郑单958和先玉335差异显著。(3)氮素利用效率随施氮量增加呈降低趋势,京科968和京农科728在不同施氮水平的氮肥农学利用率、氮肥生理利用率均高于郑单958和先玉335,且在低氮水平下优势更明显。(4)每生产100 kg籽粒需吸收纯氮量在不同施氮水平和品种间均存在显著差异。不同品种间,在4个施氮处理条件下每生产100 kg籽粒平均需吸收纯氮量表现为郑单958(2.3 kg)先玉335(2.2 kg)京农科728(2.1 kg)京科968(2.0 kg)。由此可见,京科968在土壤瘠薄条件下仍可获得较高的产量水平;氮素利用效率随施氮量增加呈降低趋势;京科968和京农科728的氮素利用效率在不同氮肥处理条件下均高于郑单958和先玉335,且由纯氮225 kg/hm~2适当减施75 kg/hm~2时减产不显著。干物质积累量高、花后干物质转运能力强、生产单位重量籽粒所需氮肥量少、氮素利用效率高是京科968和京农科728在适量减施氮肥条件下减产不显著的主要原因。

Response of Yield and Nitrogen Use Efficiency of Different Genotype Maize Varieties to Nitrogen Reducing

Using maize varieties with higher nitrogen use efficiency and yield potential is an effective approach for realizing high and stable maize yield, reducing cost and increasing efficiency. Field experiments were conducted to study the effect of nitrogen(N) reducing on maize yield and N use efficiency, by using 4 widely planted maize varieties in China, Zhengdan 958 (ZD958), Xianyu 335 (XY335), Jingke 968 (JK968) and Jingnongke 728 (JNK728), under 4 pure N application treatments with 0 kg/hm2(N0), 75 kg/hm2(N1), 150 kg/hm2(N2), 225 kg/hm2(N3). The results showed that: ① Applying N fertilizer could significantly increase the maize yield, and the yield of JK968 was the highest under 4 different N treatments with 4.1%, 7.7% and 14.6% higher than that of ZD958, XY335 and JNK728. The yield of JK968 and JNK728 decreased insignificantly, but ZD958 and XY335 decreased significantly, when N application appropriately reduced by 75 kg/hm2 (from N3 to N2). ② The single plant biomass, dry matter accumulation after anthesis and dry matter transfer rate among varieties under different N levels were different significantly. The single plant biomass of JK968 and JNK728 decreased insignificantly when N application reduced from N3 to N2, but ZD958 and XY335 decreased significantly. ③ N use efficiency decreased with the increase of N application. The agronomic utilization rate and nitrogen use efficiency of JK968 and JNK728 were higher than those of ZD958 and XY335 under different N treatments, and the dominance was obvious at lower N level. ④ The amount of N should be absorbed per 100 kg grain among different treatments and varieties differed significantly. The amount of N should be absorbed per 100 kg grain among varieties showed ZD958 (2.3 kg)>XY335 (2.2 kg)>JNK728 (2.1 kg)>JK968 (2.0 kg). Thus, JK968 had relatively higher yield level under barren conditions; N use efficiency decreased with the increase of N application; N use efficiency of JK968 and JNK728 were higher than those of ZD958 and XY335 under different N treatments, and the yield decreased insignificantly when N application appropriately reduced from N3 to N2. The higher dry matter accumulation, dry matter transfer rate after anthesis, N use efficiency and less N needed for per unit maize grain production were the main reasons for the insignificant decrease of the yield of JK968 and JNK728 when the N application appropriately reduced.