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| Effects of enhanced UV-B radiation on the content of soil active organic carbon and greenhouse gas emission from a rice paddy in Yuanyang Terraces |
| Received:August 02, 2017 Revised:October 16, 2017 |
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| KeyWord:UV-B radiation;rice paddy;soil carbon transformation;greenhouse gas emission;field experiment |
| Author Name | Affiliation | E-mail | | WANG Can | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | LI Hong-ru | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | ZHAN Fang-dong | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | LI Xiang | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | LI Yuan | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | ZU Yan-qun | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | HE Yong-mei | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | heyongmei06@126.com | | GUO Xian-hua | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | |
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| Abstract: |
| A local rice variety, Baijiaolaojing, was planted in situ in a rice paddy in Yuanyang Terraces. The effects of enhanced ultraviolet-B(UV-B) radiation at 0 and 5.0 kJ·m-2 on the contents of active organic carbon, activities of enzymes relevant to carbon transformation, and greenhouse gas emissions from the rice paddy during the rice-growing season were studied. The enhanced UV-B radiation resulted in significant decreases in the activities of polyphenol oxidase and sucrose enzymes by 10%~17%, and increases in the cellulose enzyme activities by 2.7 U·g-1 and 5.5 U·g-1 at the tillering and jointing stages. It also significantly decreased the contents of soil microbial biomass carbon and easily oxidized organic carbon by 10%~36% and 9%~31.5%, but increased the contents of soil organic carbon by 123.0, 79.5 mg·kg-1 and 57.8 mg·kg-1 at the booting, heading, and mature stages, respectively. In addition, the enhanced UV-B radiation significantly reduced the methane emission flux during the rice-growing season by 23%~42%. However, it increased the emission flux of carbon dioxide and nitrous oxide by 418.9 mg·m-2·h-1 and 3.77 μg·m-2·h-1, respectively. Furthermore, positive correlations were found between the activities of polyphenol oxidase enzyme with the contents of microbial biomass carbon as well as easily oxidized organic carbon, and between the content of microbial biomass carbon with the methane emission flux. Therefore, UV-B radiation can alter the activity of carbon invertase and the content of active organic carbon, and then affect greenhouse gas emissions from rice paddies. |
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