Journal
BMC PLANT BIOLOGY
Volume 19, Issue -, Pages -Publisher
BMC
DOI: 10.1186/s12870-019-1894-8
Keywords
Nitrogen; Potassium; Photosynthesis; Photosynthetic nitrogen allocation; Photosynthetic nitrogen use efficiency; Oryza sativa L
Categories
Funding
- National Key Research and Development Program of China [2016YFD0200108]
- Special Fund for Agro-scientific Research in the Public Interest [201503123]
- Fundamental Research Funds for the Central Universities [2662017JC010]
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BackgroundNitrogen (N) and potassium (K) are two important mineral nutrients in regulating leaf photosynthesis. Studying the interactive effects of N and K on regulating N allocation and photosynthesis (P-n) of rice leaves will be of great significance for further increasing leaf P-n, photosynthetic N use efficiency (PNUE) and grain yield. We measured the gas exchange of rice leaves in a field experiment and tested different kinds of leaf N based on N morphology and function, and calculated the interactive effects of N and K on N allocation and the PNUE.ResultsCompared with N0 (0kgNha(-1)) and K0 (0kg K2O ha(-1)) treatments, the P-n was increased by 17.1 and 12.2% with the supply of N and K. Compared with N0K0 (0kgN and 0kg K2O ha(-1)), N0K120 (0kgN and 120kg K2O ha(-1)) and N0K180 (0kgN and 180kg K2O ha(-1)), N supply increased the absolute content of photosynthetic N (N-psn) by 15.1, 15.5 and 10.5% on average, and the storage N (N-store) was increased by 32.7, 64.9 and 72.7% on average. The relative content of N-psn was decreased by 5.6, 12.1 and 14.5%, while that of N-store was increased by 8.7, 27.8 and 33.8%. Supply of K promoted the transformation of N-store to N-psn despite the leaf N content (N-a) was indeed decreased. Compared with N0K0, N180K0 (180kgN and 0kg K2O ha(-1)) and N270K0 (270kgN and 0kg K2O ha(-1)), K supply increased the relative content of N-psn by 17.7, 8.8 and 7.3%, and decreased the relative content of N-store by 24.2, 11.4 and 8.7% respectively.ConclusionsThis study indicated the mechanism that K supply decreased the N-a but increased the N-psn content and then increased leaf P-n and PNUE from a new viewpoint of leaf N allocation. The supply of K promoted the transformation of N-store to N-psn and increased the PNUE. The decreased N-store mainly resulted from the decrease of non-protein N. Combined use of N and K could optimize leaf N allocation and maintain a high leaf N-psn content and PNUE.
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