Shoot growth potential drives N uptake in maize plants and correlates with root growth in the soil |
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| Authors: | Yunfeng Peng Junfang Niu Zhengping Peng Fusuo Zhang Chunjian Li |
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| Institution: | 1. The Key Laboratory of Plant Nutrition, Ministry of Agriculture, Department of Plant Nutrition, China Agricultural University, Yuanmingyuan West Road 2, Beijing 100193, China;2. Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021, China;3. College of Resources and Environmental Sciences, Agricultural University of Hebei, Hebei 071001, China;1. State Key Laboratory of Soil Erosion and Dryland Farming, Northwest A&F University, Yangling 712100, Shaanxi, China;2. Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Northwest A&F University, Yangling 712100, Shaanxi, China;3. South Australian R&D Institute, SARDI Waite Campus Blg 11a, Hartley Grove, Urrbrae 5064, Australia;4. College of Resources and Environment, China Agriculture University, Beijing 100094, China;1. State Key Laboratory of Soil Erosion and Dryland Farming, Northwest A & F University, Yangling 712100, Shaanxi, China;2. Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Northwest A & F University, Yangling, 712100, Shaanxi, China;3. South Australian Research & Development Institute, Hartley Grove Urrbrae, 5064, Australia;4. College of Resources and Environment, China Agriculture University, Beijing 100094, China;1. Key Laboratory of Plant-Soil Interactions, Ministry of Education, Department of Plant Nutrition, China Agricultural University, Beijing 100193, China;2. Division of Plant Sciences, 1-31 Agriculture Building, University of Missouri, Columbia, MO 65211, USA;1. The Key Laboratory of Oasis Eco-agriculture, Xinjiang Production and Construction Group, College of Agronomy, Shihezi University, Shihezi 832000, China;2. Institute of Crop Sciences, Chinese Academy of Agricultural Sciences/Key Laboratory of Crop Physiology and Ecology, Ministry of Agriculture, Beijing 100081, China;3. Institute of Crop Sciences, Ningxia Academy of Agriculture Sciences, Yongning, Ningxia Hui Autonomous Region 750105, China |
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| Abstract: | Variation in nitrogen (N) acquisition ability is known to exist among maize genotypes. Field experiments were conducted and the N-efficient maize inbred line 478 and the N-inefficient line Wu312 were employed to illustrate whether the amount of N taken up in maize plants with different N acquisition ability was determined by the shoot growth potential or by the root size. To meet the accelerated growth of the shoot from the jointing stage to the grain-filling stage, the net N gain in whole plants of both genotypes increased dramatically and accounted for 77% and 74% of the total N increment in 478 and Wu312, respectively. Similarly, the 4th to 8th nodal root whorls were initiated predominantly between 35 and 76 d after sowing, which accounted for about 90% of the total root length on 93 d after sowing. The whole plant N content of the N-efficient 478 was significantly higher than that of the N-inefficient Wu312. 478 had also longer root length, including axial and lateral roots, of the embryonic roots and each whorl of shoot-borne roots, and greater root length density (RLD) than Wu312. In spite of the smaller root size, Wu312 had higher shoot N concentration than 478 during the whole growth period, implying that N was not limited for shoot growth in Wu312. It was concluded that maize root growth, especially initiation and development of the shoot-borne roots, as well as the amount of N taken up were coordinated with shoot growth and demand for nutrients. Although a large root system and high RLD in the soil profile were beneficial for efficient N acquisition, amount of N taken up by the two maize genotypes in the presence of sufficient N supply was determined by the shoot growth potential, and not by the root size. |
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