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- Title
Inhibition mechanisms of urea combined with nitrification on cadmium uptake by rice (Oryza sativa L.) seedlings.
- Authors
Li, Li; Liu, Yuling; Zhang, Shijing; Ding, Siduo; Fu, Xin; Zeng, Qingru; Peng, Liang; Luo, Si
- Abstract
Background: Cadmium (Cd) pollution in agricultural soils has been a worldwide problem that threatens eco-environmental sustainability and exerts a negative influence on plant growth. The effects of nitrification inhibitors (NIs)—namely, dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP)—on Cd phytoavailability have been reported in some studies, but the underlying mechanisms driving the changes in Cd uptake and accumulation in rice (Oryza sativa L.) seedlings are not well understood. Methods: Here, rice seedlings were transplanted into Cd-contaminated paddy soil, treated with urea and NIs (DCD or DMPP), and cultivated for 21 days. Pot experiments showed that NIs treatments significantly inhibited the ammoxidation process and increased the rhizospheric pH, thereby reducing the DTPA-extracted Cd concentration in soil and decreasing Cd accumulation in rice tissues. Besides, hydroponic culture experiments were performed to explore the impacts of NIs on Cd uptake and translocation in rice seedlings and identify the underlying mechanisms. Results: It was found that adding urea combined with NIs weakened Cd uptake by rice roots through supplying a large amount of NH4+. Furthermore, NIs applications significantly limited net Cd2+ influx and down-regulated the transcription of Cd uptake-related genes in roots via increasing NH4+, thereby decreasing the movement of Cd2+ into roots and Cd accumulation in rice. However, DMPP treatments also promoted Cd root-to-shoot translocation, likely due to the DMPP-induced increase in the expression of the OsHMA2 and OsNRAMP1 genes. Conclusions: Our results suggested that the application of appropriate ratios of NIs and nitrogen fertilizer can inhibit Cd uptake and accumulation in rice. Highlights: • Cd accumulation in rice was driven by multiple factors through NIs application. • Cd uptake in rice was mainly affected by NIs altering soil pH and Cd availability. • N forms was also regulated by NIs thus influencing Cd uptake in rice. • Urea + DMPP inhibited the expressions of NRAMP5 in rice roots. • Urea + DMPP elevated Cd translocation by promoting the HMA2 and NRAMP1 transcription.
- Subjects
NITRIFICATION inhibitors; NITRIFICATION; AGRICULTURAL pollution; CADMIUM; UREA; RICE; PADDY fields; AQUACULTURE
- Publication
Plant & Soil, 2023, Vol 485, Issue 1/2, p425
- ISSN
0032-079X
- Publication type
Article
- DOI
10.1007/s11104-022-05840-4