选用玉米早熟品种鲁原单14、中熟品种掖单22和晚熟品种掖单13，以单作为对照，研究了品种对套作和单作条件下春、夏玉米氮素利用特征以及产量的影响。结果表明，单作和套作条件下，春玉米生长期的延长有利于其吸氮量的增加，但不利于夏玉米的氮素利用。套作处理的氮素吸收效率、氮肥生产效率和氮收获指数均高于单作，但氮素利用效率介于单作春玉米和单作夏玉米之间。当春玉米对氮素的竞争能力适中，夏玉米竞争能力强时，更利于套作体系氮素优势的充分发挥。与早熟、中熟、晚熟春玉米套作组合的氮吸收土地当量比平均分别为2.46、1.63和2.04；生物产量的土地当量比平均分别为1.91、1.603和1.78。但从全年氮素利用和生物产量看，较好的套作组合是掖单13/掖单22、掖单13/掖单13和鲁原单14/掖单13。与单作相比，春夏玉米套作显著提高了全年氮素生产力和生物产量，合理的品种选择有利于套作条件下玉米高产优质潜力的充分发挥。
Three different cultivars, premature cultivars Luyuandan 14, medium cultivars Yedan 22 and late maturing cultivars Yedan 13, were chosen to study the effects of different maize cultivars on nitrogen (N) use characteristic and yield of relay-planted spring-sown and summer-sown maize compared with those of mono-planted. The results indicated that the N uptake of spring-sown maize was increased with longer growth duration. But when the longer growth duration cultivars of spring-sown maize with highest N uptake ability were used in relay-cropping, the N uptake by summer-sown maize were decreased obviously, which was not benefit to increase the annual yield. The N uptake efficiency (N accumulation in plant /N supplied, NUPE), N use efficiency (grain yield/N accumulation in plant, NUE) and N harvest index (N accumulation in grain/N accumulation in plant, NHI) were higher under relay-cropping than under sole cropping, while the N production efficiency (grain yield/N supplied, NPE) of relay cropping was between the range of spring-sown maize and summer-sown maize under sole cropping. Relay cropping of spring-sown maize with suitable N uptake ability and summer-sown maize with highest N uptake ability could enhance the advantages of the cropping system. The average land equivalent ratio for N yield of cropping system relay-planted with spring-sown maize of Luyuandan 14, Yedan 22, and Yedan 13 were 2.46, 1.63, and 2.04, respectively. While those for biomass yield were 1.91, 1.60, and 1.78, respectively. The relay cropping modes with higher N yield and biomass yield were Yedan 13/Yedan 22, Yedan 13/Yedan 13, and Luyuandan 14/Yedan 13. Compared with sole cropping maize, the relay-cropping system can get higher N productive ability and biomass yield by using more suitable cultivars.
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