Abstract:

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.

Key words: Maize, Cultivars, Cropping system, N utilization, Yield