期刊
FRONTIERS IN PLANT SCIENCE
卷 11, 期 -, 页码 -出版社
FRONTIERS MEDIA SA
DOI: 10.3389/fpls.2020.00904
关键词
biomass; enzyme activity; NUE; N-15; C-13; nitrate transporter gene expression
资金
- Special Fund for the National Key R&D Program of China [2016YFD0201100]
- NationalNatural Science Foundation of China [31501713]
- China Agriculture Research System [CARS-27]
- Taishan Scholar Assistance Program from Shandong Provincial Government
Nitrogen (N) is one of the most required mineral elements for plant growth, and potassium (K) plays a vital role in nitrogen metabolism, both elements being widely applied as fertilizers in agricultural production. However, the exact relationship between K and nitrogen use efficiency (NUE) remains unclear. Apple dwarf rootstock seedlings (M9T337) were used to study the impacts of different K levels on plant growth, nitrogen metabolism, and carbon (C) assimilation in water culture experiments for 2 years. The results showed that both deficiency and excess K inhibited the growth and root development of M9T337 seedlings. When the K supply concentration was 0 mM and 12 mM, the biomass of each organ, root-shoot ratio, root activity and NO(3)(-)ion flow rate decreased significantly, net photosynthetic rate (P-n) and photochemical efficiency (F-v/F-m) being lower. Meanwhile, seedlings treated with 6 mM K(+)had higher N and C metabolizing enzyme activities and higher nitrate transporter gene expression levels (NRT1.1;NRT2.1).C-13 and(15)N labeling results showed that deficiency and excess K could not only reduce(15)N absorption and(13)C assimilation accumulation of M9T337 seedlings, but also reduced the(15)N distribution ratio in leaves and(13)C distribution ratio in roots. These results suggest that appropriate K supply (6 mM) was optimal as it enhanced photoassimilate transport from leaves to roots and increased NUE by influencing photosynthesis, C and N metabolizing enzyme activities, nitrate assimilation gene activities, and nitrate transport.
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