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Zhang J.,Shandong Agricultural University | Zhang J.,Yanzhou Institute of Agricultural science | Wu T.-H.,Yanzhou Institute of Agricultural science | Dai X.-L.,Shandong Agricultural University | And 4 more authors.
Chinese Journal of Applied Ecology | Year: 2015

A two-year (2011-2012 and 2012-2013) field experiment was conducted on one winter wheat cultivar supplied with two levels of nitrogen (180 and 240 kg N·hm-2) under three plant densities (135×104, 270×104, and 405×104 plants·hm-2). The 15N-labeled urea was injected into 20, 60 and 100 cm soil depths, respectively, aiming to investigate the effect of nitrogen and plant density and their interaction on the N uptake, utilization and nitrate nitrogen contents at different soil depths. The results showed that increasing the plant density from 135×104 to 405×104 plants·hm-2 significantly increased the 15N uptake at depths of 20, 60 and 100 cm averagely by 1.86, 2.28 and 2.51 kg·hm-2, respectively, and increased the above ground N uptake (AGN), N uptake efficiency (UPE) averagely by 12.6% and 12.6%, respectively, but decreased the N utilization efficiency (UTE) by 5.4%. Compared to the N input of 240 kg N·hm-2, the 180 kg N·hm-2 significantly reduced the 15N uptake at depths of 20 and 60 cm averagely by 4.11 and 1.21 kg·hm-2, respectively, and significantly increased the 15N uptake at depths of 100 cm averagely by 1.02 kg·hm-2. Reducing the N input decreased the AGN averagely by 13.5%, but significantly increased the UPE and UTE by 9.4% and 12.2%, respectively. Equivalent grain yield was observed among N input of 180 kg N·hm-2 with plant density of 405×104 plants·hm-2 and N input of 240 kg N·hm-2 with plant densities of 270×104 and 405×104 plants·hm-2. Increasing the plant density or reducing the N input could encourage the N uptake at deep soil profile and increased UPE and UTE by 13.4% and 11.9%, respectively. Meanwhile, both the nitrate nitrogen contents in 0-200 cm soil layers at maturity and the ratio of the nitrate nitrogen in 100-200 cm soil layers to that in 0-200 cm were significantly decreased. Therefore, properly decreasing the N input with increasing the plant density of winter wheat was efficient in absorbing N at deep soil, synergistically obtaining high grain yield, UPE and UTE, and reducing the pollution of residual soil nitrate. ©, 2015, Editorial Board of Chinese Journal of Applied Ecology. All right reserved.

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