title: A high plant density reduces the ability of maize to use soil nitrogen.
abstract: Understanding the physiological changes associated with high grain yield and high N use efficiency (NUE) is important when increasing the plant density and N rate to develop optimal agronomic management. We tested the hypothesis that high plant densities resulting in crowding stress reduce the ability of plants to use the N supply post-silking, thus decreasing the grain yield and NUE. In 2013 and 2014, a field experiment, with five N-application rates and three plant densities (6.0, 7.5, and 9.0 plants m-2), was conducted in the North China Plain (NCP). The calculated maximum grain yield and agronomic use efficiency (AEN) at a density of 7.5 plants m-2 were 12.4 Mg ha-1 and 39.3 kg kg-1, respectively, which were significantly higher than the values obtained at densities of 6.0 (11.3 Mg ha-1 and 30.2 kg kg-1) and 9.0 plant m-2 (11.7 Mg ha-1 and 27.8 kg kg-1). A high plant density of 9.0 plants m-2 decreased the post-silking N accumulation, leaf N concentration and net photosynthesis, which reduced the post-silking dry matter production, resulting in a low yield and NUE. Although a relatively low grain yield was observed at a density of 9.0 plants m-2, the optimal N rate increased from 150 to 186 kg N ha-1 at a density of 7.5 plants m-2. These results indicate that high plant densities with crowding stress reduce the ability of plants to use soil N during the post-silking period, and high rate of N fertilizer was needed to increase grain yield. We conclude that selecting the appropriate plant density combined with optimal N management could increase grain yields and the NUE in the NCP.
authors.affiliation: Key Laboratory of Plant-Soil Interactions, Ministry of Education, Center for Resources, Environment and Food Security, China Agricultural University, Beijing, China.|Key Laboratory of Tea Biology and Resources Utilization, Ministry of Agriculture, Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou China.
authors.forename: Peng
authors.initials: P
authors.lastname: Yan
authors.affiliation: Key Laboratory of Plant-Soil Interactions, Ministry of Education, Center for Resources, Environment and Food Security, China Agricultural University, Beijing, China.
authors.forename: Junxiao
authors.initials: J
authors.lastname: Pan
authors.affiliation: Key Laboratory of Plant-Soil Interactions, Ministry of Education, Center for Resources, Environment and Food Security, China Agricultural University, Beijing, China.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Plant-Soil Interactions, Ministry of Education, Center for Resources, Environment and Food Security, China Agricultural University, Beijing, China.
authors.forename: Junfang
authors.initials: J
authors.lastname: Shi
authors.affiliation: Key Laboratory of Plant-Soil Interactions, Ministry of Education, Center for Resources, Environment and Food Security, China Agricultural University, Beijing, China.
authors.forename: Xinping
authors.initials: X
authors.lastname: Chen
authors.affiliation: Key Laboratory of Plant-Soil Interactions, Ministry of Education, Center for Resources, Environment and Food Security, China Agricultural University, Beijing, China.
authors.forename: Zhenling
authors.initials: Z
authors.lastname: Cui
mesh_terms: D000383:Agriculture; D005308:Fertilizers; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation / Q000502:physiology*; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism; D018521:Plant Physiological Phenomena; D011156:Population Density; D012987:Soil / Q000737:chemistry; D013472:Sunlight; D003313:Zea mays / Q000254:growth & development* / Q000378:metabolism
chemical_list: D005308:Fertilizers; D012987:Soil; D009584:Nitrogen