Within-leaf nitrogen allocation in adaptation to low nitrogen supply in maize during grain-filling stage

• Main Authors: Xiaohuan eMu, Qinwu eChen, Fanjun eChen, Lixing eYuan, Guohua eMi
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2016-05-01
• Series: Frontiers in Plant Science
• Subjects: Nitrogen; Phosphoenolpyruvate Carboxylase; Bioenergetics; photosynthetic rate; light harvesting; Photosynthetic nitrogen use efficiency
• Online Access: http://journal.frontiersin.org/Journal/10.3389/fpls.2016.00699/full

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 (Pn) 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 Pn, 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 Pn and crop productivity when N is limited during the grain-filling stage in maize under low-N conditions.