title: Within-Leaf Nitrogen Allocation in Adaptation to Low Nitrogen Supply in Maize during Grain-Filling Stage.
abstract: Nitrogen (N) plays a vital role in photosynthesis and crop productivity. Maize plants may be able to increase physiological N utilization efficiency (NUtE) under low-N stress by increasing photosynthetic rate (P n) per unit leaf N, that is, photosynthetic N-use efficiency (PNUE). In this study, we analyzed the relationship between PNUE and N allocation in maize ear-leaves during the grain-filling stage under low N (no N application) and high N (180 kg N ha(-1)) in a 2-year field experiment. Under low N, grain yield decreased while NUtE increased. Low-N treatment reduced the specific N content of ear leaves by 38% without significant influencing P n, thereby increasing PNUE by 54%. Under low-N stress, maize plants tended to invest relatively more N into bioenergetics to sustain electron transport. In contrast, N allocated to chlorophyll and light-harvesting proteins was reduced to control excess electron production. Soluble proteins were reduced to shrink the N storage reservoir. We conclude that optimization of N allocation within leaves is a key adaptive mechanism to maximize P n and crop productivity when N is limited during the grain-filling stage in maize under low-N conditions.
authors.affiliation: Center for Resources, Environment and Food Security, College of Resources and Environmental Science, China Agricultural University Beijing, China.
authors.forename: Xiaohuan
authors.initials: X
authors.lastname: Mu
authors.affiliation: Center for Resources, Environment and Food Security, College of Resources and Environmental Science, China Agricultural University Beijing, China.
authors.forename: Qinwu
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Center for Resources, Environment and Food Security, College of Resources and Environmental Science, China Agricultural University Beijing, China.
authors.forename: Fanjun
authors.initials: F
authors.lastname: Chen
authors.affiliation: Center for Resources, Environment and Food Security, College of Resources and Environmental Science, China Agricultural University Beijing, China.
authors.forename: Lixing
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Center for Resources, Environment and Food Security, College of Resources and Environmental Science, China Agricultural University Beijing, China.
authors.forename: Guohua
authors.initials: G
authors.lastname: Mi
keywords: 5-bisphosphate carboxylase; bioenergetics; light harvesting; phosphoenolpyruvate carboxylase; photosynthetic nitrogen use efficiency; photosynthetic rate; pyruvate orthophosphate dikinase; ribulose-1; thylakoid nitrogen