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| Effect of UV-B radiation on grain morphology and proanthocyanidins content and distribution of Yuanyang red rice |
| Received:September 25, 2019 |
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| KeyWord:UV-B radiation;red rice;grain shape;proanthocyanidins;paraffin sections |
| Author Name | Affiliation | E-mail | | SHENG Jian-jun | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | LI Xiang | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | ZHANG Yan-xue | 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 | | | XIE Chun-mei | 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 | | | LI Yuan | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | liyuan@ynau.edu.cn |
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| Abstract: |
| In order to elucidate the effect of UV-B radiation on the content and distribution of proanthocyanidins in rice grains, Baijiaolaojing, a traditional rice variety in Yuanyang Terraces, was planted in a rice paddy field in situ, under different intensities of UV-B radiation treatments(0 kJ·m-2·d-1, 2.5 kJ·m-2·d-1, 5.0 kJ·m-2·d-1, and 7.5 kJ·m-2·d-1)during the rice growing period. The effect of UV-B radiation on grain morphology, content, and distribution of proanthocyanidin in rice were investigated. Results showed that the grain length, width, 1000-grain weight, biomass, and yield of rice grains per plant were inhibited under UV-B radiation. The grain length and width, as inhibited by UV-B radiation, decreased significantly by 11.6% and 5%, respectively, with a UV-B radiation intensity of 7.5 kJ·m-2·d-1. The 1000-grain weight and grain biomass decreased significantly with the enhanced UV-B radiation, reaching their minimum of 17.41 g and 20.84 g, respectively, with the same UV-B radiation intensity. The yield also decreased significantly at the same UV-B radiation intensity. The proanthocyanidin content in rice husk showed a single-peak curve under different UV-B radiation treatments, reaching a maximum of 4.06 μg·g-1·d-1 at the intensity of 5.0 kJ·m-2·d-1. The proanthocyanidin content in brown rice did not change significantly under the same UV-B radiation intensity, but decreased significantly when the intensity was 7.5 kJ·m-2·d-1. Proanthocyanidin content in rice grains decreased from the outside to inside. Proanthocyanidins were mainly concentrated on the surface of pericarp and endosperm. In the vertical structure(parallel to the line connecting awn and spikelet axes), the area proportion of proanthocyanidins was inhibited under enhanced UV-B radiation. In the horizontal structure(perpendicular to the line connecting awn and spikelet axes), the area proportion of proanthocyanidins was promoted under UV-B radiation. In summary, the results indicate that the enhanced UV-B radiation can change the grain structure and promote the synthesis of proanthocyanidins in rice husk. The synthesis of proanthocyanidins in rice husk and brown rice is inhibited under a UV-B radiation intensity of 7.5 kJ·m-2·d-1. UV-B radiation can affect the distribution of proanthocyanidins; the area proportion of proanthocyanidins of the horizontal structure enhanced by the UV-B radiation is significantly higher than that of the vertical structure in rice grains. |
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