title: Temporal and spatial profiling of root growth revealed novel response of maize roots under various nitrogen supplies in the field.
abstract: A challenge for Chinese agriculture is to limit the overapplication of nitrogen (N) without reducing grain yield. Roots take up N and participate in N assimilation, facilitating dry matter accumulation in grains. However, little is known about how the root system in soil profile responds to various N supplies. In the present study, N uptake, temporal and spatial distributions of maize roots, and soil mineral N (N(min)) were thoroughly studied under field conditions in three consecutive years. The results showed that in spite of transient stimulation of growth of early initiated nodal roots, N deficiency completely suppressed growth of the later-initiated nodal roots and accelerated root death, causing an early decrease in the total root length at the rapid vegetative growth stage of maize plants. Early N excess, deficiency, or delayed N topdressing reduced plant N content, resulting in a significant decrease in dry matter accumulation and grain yield. Notably, N overapplication led to N leaching that stimulated root growth in the 40-50 cm soil layer. It was concluded that the temporal and spatial growth patterns of maize roots were controlled by shoot growth and local soil N(min), respectively. Improving N management involves not only controlling the total amount of chemical N fertilizer applied, but also synchronizing crop N demand and soil N supply by split N applications.
authors.affiliation: Key Laboratory of Plant-Soil Interactions, Ministry of Education, Department of Plant Nutrition, China Agricultural University, Beijing, China.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Peng
authors.forename: Xuexian
authors.initials: X
authors.lastname: Li
authors.forename: Chunjian
authors.initials: C
authors.lastname: Li
mesh_terms: D000383:Agriculture / Q000379:methods*; D000704:Analysis of Variance; D002681:China; D005308:Fertilizers; D009584:Nitrogen / Q000172:deficiency / Q000493:pharmacokinetics / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects* / Q000254:growth & development*; D012987:Soil / Q000032:analysis; D003313:Zea mays
chemical_list: D005308:Fertilizers; D012987:Soil; D009584:Nitrogen