Low crown root number enhances nitrogen acquisition from low-nitrogen soils in maize.
In developing nations, low soil nitrogen (N) availability is a primary limitation to crop production and food security, while in rich nations, intensive N fertilization is a primary economic, energy, and environmental cost to crop production. It has been proposed that genetic variation for root architectural and anatomical traits enhancing the exploitation of deep soil strata could be deployed to develop crops with greater N acquisition. Here, we provide evidence that maize (Zea mays) genotypes with few crown roots (crown root number [CN]) have greater N acquisition from low-N soils. Maize genotypes differed in their CN response to N limitation in greenhouse mesocosms and in the field. Low-CN genotypes had 45% greater rooting depth in low-N soils than high-CN genotypes. Deep injection of (15)N-labeled nitrate showed that low-CN genotypes under low-N conditions acquired more N from deep soil strata than high-CN genotypes, resulting in greater photosynthesis and plant N content. Under low N, low-CN genotypes had greater biomass than high-CN genotypes at flowering (85% in the field study in the United States and 25% in South Africa). In the field in the United States, 1.8× variation in CN was associated with 1.8× variation in yield reduction by N limitation. Our results indicate that CN deserves consideration as a potential trait for genetic improvement of N acquisition from low-N soils.
Intercollege Program in Plant Biology (P.S., J.P.L.) and Department of Plant Science (X.T., J.P.L.), Pennsylvania State University, University Park, Pennsylvania 16802; andState Key Laboratory of Plant Physiology and Biochemistry, and Department of Agronomy, China Agricultural University, Beijing 100193, China (X.T.).
Patompong
P
Saengwilai
Intercollege Program in Plant Biology (P.S., J.P.L.) and Department of Plant Science (X.T., J.P.L.), Pennsylvania State University, University Park, Pennsylvania 16802; andState Key Laboratory of Plant Physiology and Biochemistry, and Department of Agronomy, China Agricultural University, Beijing 100193, China (X.T.).
Xiaoli
X
Tian
Intercollege Program in Plant Biology (P.S., J.P.L.) and Department of Plant Science (X.T., J.P.L.), Pennsylvania State University, University Park, Pennsylvania 16802; andState Key Laboratory of Plant Physiology and Biochemistry, and Department of Agronomy, China Agricultural University, Beijing 100193, China (X.T.) jpl4@psu.edu.
Jonathan Paul
http://orcid.org/0000-0002-7265-9790
JP
Lynch
D002244:Carbon / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*; D013312:Stress, Physiological; D003313:Zea mays / Q000378:metabolism*
D012987:Soil; D002244:Carbon; D009584:Nitrogen