Objectives This study is to investigate grain yield, nitrogen uptake and use efficiency of summer maize with different plant height in response to plant density and nitrogen rate.
Methods Three hybrids: high-stalk (Ludan981, LD981), medium-stalk (Zhengdan958, ZD958) and short-stalk (Denghai661, DH661) were used as experimental materials in a field experiment. Two plant densities of 67500 and 82500 plants/hm2, and three nitrogen rate of 0, 180 and 270 kg/hm2 were designed for each hybrid. The yield, N contents and accumulation were investigated; the N translocation rate and their contribution to yield were calculated.
Results The grain yields of three hybrids DH661, ZD958 and LD981 in density of 82500 plants/hm2 were 5.0%, 10.2% and 12.5% higher than those in density of 67500 plants/hm2, but the differences between N treatment of 180 and 270 kg/hm2 were not significant under the two densities. When the density was 82500 plants/hm2, the nitrogen translocation efficiency (NTE) and nitrogen contribution proportion (NCP) of DH661 in N 270 kg/hm2 were significantly lower than those in N 180 kg/hm2, those of hybrids of ZD958 and LD981 were not varied obviously. When the density was 67500 plants/hm2, the NTE and NCP of DH661 and ZD958 in N 270 kg/hm2 were higher than those in N 180 kg/hm2, but those of LD981 were opposite. Nitrogen use efficiency (NUE) of DH661 was 7.4% and 39.1% higher than those of ZD958 and LD981 respectively, and nitrogen uptake efficiency (NUPE) of LD981 was 18.9% and 25.0% higher than those of ZD958 and DH661, respectively.
Conclusions Under density of 67500 plant/hm2, high nitrogen fertilizer input will decrease the nitrogen translocation efficiency and nitrogen contribution of medium and short stalk hybrids but increase those of high stalk hybrid. Under high density of 82500 plant/hm2, high N fertilizer rate will significantly decrease the two items of short hybrid, but not decrease those of medium and high stalk hybrids.
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