Abstract: Moderate densification and nitrogen (N) fertilizer rate is important to improve maize yield and fertilizer use efficiency. The 2-year field trials from 2015 to 2016 in Yuzhou city in Henan province was conducted, including 2 maize varieties (Weike 702 and Zhongdan 909), 3 N levels (0 kg·hm^-2, N0; 180 kg·hm^-2, N180; 360 kg·hm^-2, N360), 4 plant densities (4.5×104 plant·hm^-2, D45; 6.0×104 plant·hm^-2, D60; 7.5×104 plant·hm^-2, D75; 9.0×104 plant·hm^-2, D90), to study the effects of different plant density and N application rate on maize yield and yield composition, phosphorus (P) and potassium (K) accumulation, absorption and utilization efficiency. The results showed that the maize yield increased first and then decreased with the increasing of plant density. The low N application at the same planting density increased maize yield, and the higher the plant density, the greater the increase in yield, with increase rate of 0.49%, 0.73%, 5.38% and 7.81% at D45, D60, D75, D90 plant density, respectively. Under the condition of high plant density, the yield increased by 17.28% under low N application for Weike 702, but no significant difference for Zhongdan 909. In terms of yield composition, with the increase of plant density, spike per unit increased, grain number per spike and 1 000-grain weight decreased. The effect of low N application on spike per unit and 1 000-grain weight was small, but the effect on grain number per spike was consistent with the yield. When the plant density increased to D75, the P and K accumulation of maize increased gradually, while the P and K accumulation decreased when the density further increased to D90, with a higher decrease of Weike 702 than Zhongdan 909. Under the same density, the P and K accumulation of maize with low N application increased by 1530% and 17.91% compared with high N treatment. The partial factor productivity and absorption efficiency of P and K increased first and then decreased, while the harvest index and utilization efficiency decreased with the increasing plant density. Under densification conditions (D75 and D95), the partial factor productivity and P harvest index were improved obviously, but the K harvest index and the transport efficiency were decreased. In conclusion, the low N fertilizer application of 180 kg·hm^-2 and plant density of 7.5×104 plant·hm^-2 could improve maize yield, uptake and utilization of P and K.

Key words: plant density, nitrogen application rate, maize yield, phosphorus and potassium, fertilizer use efficiency

摘要： 为明确施氮量和种植密度对玉米产量和磷钾吸收利用的影响，于2015—2016连续2年在河南省禹州市开展大田试验，选用伟科702和中单909，设置不施氮（0 kg·hm^-2，N0）、低氮（180 kg·hm^-2，N180）、高氮（360 kg·hm^-2，N360)三个施氮水平，4.5×104（D45）、6.0×104（D60）、7.5×104（D75）、9.0×104 株·hm^-2（D90）四个种植密度，分析不同因素对玉米产量及构成、磷钾累积及吸收利用效率的影响。结果表明：玉米产量随密度提高呈先增加后降低的趋势；相同密度下低氮处理提高了玉米产量，密度越高增产量幅度越大，D45、D60、D75、D90密度下玉米产量分别增加0.49%、0.73%、5.38%、7.81%；高密条件下，伟科702的N180处理比N360处理增产17.28%，而中单909的两个处理的产量间无差异。随着密度增加，有效穗数增加，穗粒数和千粒重下降；施氮量对有效穗和千粒重的影响较小，对穗粒数的影响与产量变化趋势一致。大喇叭口期以后，各处理玉米磷、钾吸收的差异逐渐变大。随着密度增加，玉米磷、钾吸收量逐渐增加，密度从D75增加至D90，则磷、钾累积量降低，其中伟科702降幅显著高于中单909。相同密度下，N180比N360处理提高了玉米磷、钾素累积，成熟期磷和钾素累积量平均提高了15.30%和17.91%。随密度增加，磷、钾偏生产力和吸收效率呈先增加后降低的趋势，而收获指数和利用效率呈下降趋势。低氮处理提高了玉米的磷、钾吸收效率，且增密处理（D75和D95）提高了磷、钾偏生产力及磷收获指数，但降低了钾收获指数和磷、钾转运效率。本研究条件下，施氮180 kg·hm^-2和种植密度7.5×104株·hm^-2可提高玉米产量和磷、钾素吸收，优化磷、钾肥的利用效率，研究结果为我国玉米合理栽培与施肥提供理论依据。

关键词: 种植密度, 施氮量, 玉米产量, 磷、钾素积累, 肥料利用率