Within-Leaf Nitrogen Allocation in Adaptation to Low Nitrogen Supply in Maize during Grain-Filling Stage

• Published in: Frontiers in plant science Vol. 7; p. 699
• Main Authors: Mu, Xiaohuan, Chen, Qinwu, Chen, Fanjun, Yuan, Lixing, Mi, Guohua
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 24.05.2016
• Subjects: Bioenergetics; light harvesting; Nitrogen; Phosphoenolpyruvate Carboxylase; Photosynthetic nitrogen use efficiency; photosynthetic rate; Plant Science; photosynthetic nitrogen use efficiency; light harvesting; bioenergetics; 5-bisphosphate carboxylase; photosynthetic rate; phosphoenolpyruvate carboxylase; thylakoid nitrogen; ribulose-1; pyruvate orthophosphate dikinase
• DOI: 10.3389/fpls.2016.00699
• ISSN: 1664-462X

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.