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Purpose <p>Climate warming and enhanced UV-B radiation are major global ecological issues of increasing concern. However, current research on the carbon balance in rice field ecosystems has primarily focused on studying enhanced UV-B radiation and rising temperature as separate, individual factors. This approach fails to fully simulate actual field conditions, where these stressors (resulting from the ozone hole and the greenhouse effect, respectively) occur simultaneously and may interact to influence the rice field carbon pool.</p> Methods <p>This study employed an in-situ field experiment on the traditional rice cultivar Whitefoot Japonica in the Yuanyang terraces, conducted from March (sowing) to May (transplanting) 2022. The experiment comprised four treatments: control (CK), elevated temperature (T, + 2&#xa0;°C), enhanced UV-B radiation (U, + 5.0&#xa0;kJ·m⁻²), and their combination (UT). Each plot measured 2.25&#xa0;m (width) × 3&#xa0;m (length), spaced 0.5&#xa0;m apart, and was surrounded by border rows as guards.</p> Results <p>UV-B radiation significantly increased the soil dissolved organic carbon (DOC) content by 57%, 31%, and 31% during the rice tillering, booting, and maturity stages, respectively. It also raised the readily oxidizable organic carbon (ROC) by 26% at the booting stage. In contrast, the warming treatment significantly enhanced the ROC content by 42% at the maturity stage and increased the soil microbial biomass carbon (MBC) by 95% and 24% during the tillering and booting stages, respectively. Furthermore, the combined treatment of warming and UV-B led to a 29% increase in DOC during the tillering stage and a 25% rise in ROC at the maturity stage. Concurrently, all treatments—warming, enhanced UV-B radiation, and their combination—significantly suppressed β-glucosidase activity. Warming alone also inhibited the growth of <i>Chloroflexi</i> bacterial communities, which are involved in soil carbon decomposition. At the same time, warming, enhanced UV-B radiation and their combined treatments significantly inhibited β-glucosidase activity in the soil, and warming also inhibited the growth of <i>Chloroflexi</i> bacterial communities involved in soil carbon decomposition. Regarding greenhouse gas emissions, UV-B radiation reduced the total emissions of CH₄ by 47%, respectively, over the rice breeding period. While elevated temperature increased CH₄ emissions by 34%, the combined treatment resulted in a 37% reduction.</p> Conclusion <p>Enhanced UV-B radiation counteracted the promotive effect of elevated temperature on the transformation of labile organic carbon in paddy soil and reduced CH₄ emissions.</p>

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Elevated temperature and enhanced UV-B radiation inhibited the decomposition and transformation of activated organic carbon in paddy soils

  • 期刊论文

  • 发表日期：

    2026年1月19日

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  • Yonglin Wu,
  • Qinghao Zhang,
  • Min Yang,
  • Haitao Li,
  • Mingrui Li,
  • Yang Li,
  • Yuan Li,
  • Yongmei He

摘要

Purpose

Climate warming and enhanced UV-B radiation are major global ecological issues of increasing concern. However, current research on the carbon balance in rice field ecosystems has primarily focused on studying enhanced UV-B radiation and rising temperature as separate, individual factors. This approach fails to fully simulate actual field conditions, where these stressors (resulting from the ozone hole and the greenhouse effect, respectively) occur simultaneously and may interact to influence the rice field carbon pool.

Methods

This study employed an in-situ field experiment on the traditional rice cultivar Whitefoot Japonica in the Yuanyang terraces, conducted from March (sowing) to May (transplanting) 2022. The experiment comprised four treatments: control (CK), elevated temperature (T, + 2 °C), enhanced UV-B radiation (U, + 5.0 kJ·m⁻²), and their combination (UT). Each plot measured 2.25 m (width) × 3 m (length), spaced 0.5 m apart, and was surrounded by border rows as guards.

Results

UV-B radiation significantly increased the soil dissolved organic carbon (DOC) content by 57%, 31%, and 31% during the rice tillering, booting, and maturity stages, respectively. It also raised the readily oxidizable organic carbon (ROC) by 26% at the booting stage. In contrast, the warming treatment significantly enhanced the ROC content by 42% at the maturity stage and increased the soil microbial biomass carbon (MBC) by 95% and 24% during the tillering and booting stages, respectively. Furthermore, the combined treatment of warming and UV-B led to a 29% increase in DOC during the tillering stage and a 25% rise in ROC at the maturity stage. Concurrently, all treatments—warming, enhanced UV-B radiation, and their combination—significantly suppressed β-glucosidase activity. Warming alone also inhibited the growth of Chloroflexi bacterial communities, which are involved in soil carbon decomposition. At the same time, warming, enhanced UV-B radiation and their combined treatments significantly inhibited β-glucosidase activity in the soil, and warming also inhibited the growth of Chloroflexi bacterial communities involved in soil carbon decomposition. Regarding greenhouse gas emissions, UV-B radiation reduced the total emissions of CH₄ by 47%, respectively, over the rice breeding period. While elevated temperature increased CH₄ emissions by 34%, the combined treatment resulted in a 37% reduction.

Conclusion

Enhanced UV-B radiation counteracted the promotive effect of elevated temperature on the transformation of labile organic carbon in paddy soil and reduced CH₄ emissions.