[Contribution of nutrient uptake and utilization on yield advantage in maize and potato intercropping under different nitrogen application rates].

Intercropping of maize and potato, as an important intercropping planting pattern, has a prominent advantage of resource utilization and yield. However, contribution of nutrient uptake and utilization to crop yield advantage and its response to N application rates remain unclear. Through a 2-year plot experiment, including maize monoculture, potato monoculture and maize intercropping with potato at 4 N-fertilized levels of N0(0 kg·hm-2), N1(125 kg·hm-2), N2(250 kg·hm-2) and N3(375 kg·hm-2), nutritional contribution of yield advantage of intercropping was studied. The results showed that weighted average uptake of nitrogen, phosphorus and potassium was gradually increased with N application rate in monocultures, but increase followed by a decrease in intercropping. Compared with monoculture at the same N level, nutrient uptake advantage of intercropping was the highest at N1, which increased nitrogen, phosphorus and potassium uptake by 14.9%, 38.6% and 27.8%, respectively. However, the nutrient use efficiencies were highest in intercropping at N0 and N3 with increment of 3.5%-14.3% for nitrogen, 3.5%-18.5% for phosphorus and 10.6%-31.6% for potassium. Maize and potato intercropping had a significant yield advantage at N0 and N1. Yield advantage in intercropping attributed to improvement of nutrient use efficiency at N0 while to increase of nutrient uptake at N1. To utilize the yield advantage from nutrient uptake, controlling input of nitrogen fertilizer is necessary in intercropping.玉米与马铃薯间作是重要的间作种植模式,具有较突出的资源利用和产量优势,但养分吸收和利用对作物产量优势的贡献及这种贡献对施氮量的响应机制尚不清楚.本研究采用玉米单作、马铃薯单作和玉米与马铃薯间作3种种植模式,分别设置N0(0 kg·hm-2)、N1(125 kg·hm-2)、N2(250 kg·hm-2)和N3(375 kg·hm-2)4个氮水平,通过2年田间小区试验,研究不同氮水平下间作产量优势的营养基础.结果表明: 随着施氮量的增加,氮、磷、钾的单作加权平均吸收量逐渐增加,间作则先增加后减少.间作在N1水平时具最高的养分吸收优势,分别较单作加权平均值增加氮吸收14.9%、磷吸收38.6%、钾吸收27.8%;间作在N0和N3时具有更高的养分利用效率,较单作可提高氮利用效率3.5%～14.3%、磷利用效率3.5%～18.5%、钾利用效率10.6%～31.6%.N0和N1时玉米与马铃薯间作具有显著产量优势,其营养基础在N0时主要是提高了作物养分利用效率,而N1时则是促进养分吸收的结果.充分发挥间作促进养分吸收对玉米与马铃薯间作产量优势的贡献,需要合理控制氮肥的投入.