Effects of enhanced UV-B radiation on nitrogen transformation and functional biological properties in the rice rhizosphere

ABSTRACT

To clarify the effect of enhanced UV-B radiation on soil nitrogen transformation and its biological processes in paddy fields, the effects of enhanced ultraviolet-B radiation (0, 2.5, 5.0 and 7.5 kJ m⁻²) on soil nitrogen transformation and N₂O emission, functional microbial quantity, enzyme activity, and gene expression during the growth period (tillering, jointing, booting and maturity stage) of rice were investigated in situ in a rice paddy field in the Yuanyang terraces, Yunnan Province, southwest China. The results show that UV-B radiation decreased the NH₄⁺-N content, increased the NO₃^–N content in the rhizosphere, decreased N₂O emissions from paddy fields, and significantly affected the properties of soil nitrogen transforming microorganisms. The 5.0 kJ m⁻² UV-B radiation increased the quantity of ammonifying bacteria and ammonia oxidizing bacteria by 18–160% and 34–151%, respectively, decreased the urease activity in the rice rhizosphere by 11.9–27%; and significantly increased the expression of AOB-amoA and nosZ genes. Thus, the enhanced UV-B radiation increased the ammonia-oxidizing bacteria and AOB-amoA and nosZ gene expression, promoted the transformation of NH₄⁺-N to NO₃^–N in the rice rhizosphere, and reduced N₂O emissions in the paddy field.

KEYWORDS:

• UV-B radiation
• rice rhizosphere
• nitrogen transformation
• gene expression
• N₂O emissions

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Nos. 32060287 and 41565010) and the Reserve Talents Funds for Young and Middle-Aged Academic and Technological leaders in Yunnan Province (202005AC160038).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authors’ contributions

Huichuan Xiao: Conceptualization, writing (original draft), Software.

Yanxue Zhang: Methodology, investigation, writing (original draft), data curation.

Jiong Wu: Methodology, formal analysis.

Zuran Li: Methodology, investigation.

Yuan Li: Methodology, writing (original draft preparation), investigation.

Fangdong Zhan: Funding acquisition, project administration, supervision.

Yongmei He: Conceptualization, Funding acquisition, data curation, writing (review and editing), project administration, supervision.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (Nos. 32060287 and 41565010) and the Reserve Talents Funds for Young and Middle-Aged Academic and Technological leaders in Yunnan Province (202005AC160038)