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| Effect of UV-B radiation on photosynthetic characteristics of Japonica rice during vegetative growth |
| Received:April 15, 2020 |
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| KeyWord:UV-B;Japonica rice;vegetative growth;photosynthetic electron transport;fluorescence induction kinetic parameters |
| Author Name | Affiliation | E-mail | | ZHAN Shen-ye | Anshan Meteorological Administration, Anshan 114004, China
College of Agriculture, Shenyang Agricultural University, Shenyang 110866, China | | | LÜ Xiao | Jinzhou Ecological and Agricultural Meteorological Center, Jinzhou 121000, China | | | JIN Dan-dan | Plant Nutrition and Environmental Resources Research Institute, Liaoning Academy of Agricultural Science, Shenyang 110161, China | | | YIN Hong | College of Agriculture, Shenyang Agricultural University, Shenyang 110866, China | 952560318@qq.com |
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| Abstract: |
| In order to analyze the effect of enhanced UV-B radiation on the photosynthetic characteristics of Japonica rice during vegetative growth, an experiment was conducted to determine the characteristics of photosynthetic electron transport and fluorescence induction kinetics curves (OJIP)and their parameters. The Japonica variety Shen-nong 265 was used and was exposed to either natural light (CK)or enhanced UV-B radiation. The UV-B radiation was increased by 5% as the T1 treatment, increased by 10% as the T2, respectively. UV-B radiation enhancement reduced photorespiratory electron flow (Jo)and carbon electron flow (Jc)to different degrees; under T2, Jo was inhibited more compared to under T1, while Jo/JF and Jo/Jc were increased to different degrees. UV-B treatment showed insignificant trends regarding Rubisco oxidation rate (Vo); however, Rubisco carboxylation rate (Vc) was reduced significantly. Vo/Vc showed increasing trend, which was positively correlated with UV-B radiation intensity. UV-B radiation reduced the P-phase value of the OJIP curve. The original light energy conversion efficiency (Fv/Fm), smooth quenching coefficient (qP), and relative rate of photosynthetic electron transfer (rETR) decreased during the 20th, 40th and 60th days after transplanting, but the non-photochemical quenching coefficient (NPQ)increased. Fv/Fm, qP, and rETR were inhibited to a greater extent under T2 than under T1. Thus, the enhanced UV-B radiation during the vegetative growth period enhanced the proportion of photorespiratory electron flow, reduced the proportion of carbon reduction electron flow, and also reduced the Rubisco carboxylation rate. Ultimately, it affected the relative fluorescence yield of leaves. The enhanced UV-B radiation suppressed the degree of photochemical quenching of vegetative growth leaves, but promoted the rate of non-photochemical quenching; the photoelectron transfer rate was also reduced. |
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