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| Effects of cadmium stress on photosynthetic physiology and chlorophyll fluorescence in Solanum nigrum and Solanum americanum |
| Received:July 16, 2020 |
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| KeyWord:Cd stress;Solanum nigrum;Solanum americanum;chlorophyll fluorescence;photosynthetic physiology |
| Author Name | Affiliation | E-mail | | ZHOU Jiao | College of Landscape Architecture, Sichuan Agricultural University, Chengdu 611130, China | | | HAN Pan-pan | College of Landscape Architecture, Sichuan Agricultural University, Chengdu 611130, China | | | PAN Yuan-zhi | College of Landscape Architecture, Sichuan Agricultural University, Chengdu 611130, China | scpyzls@163.com | | WU Meng-xi | College of Landscape Architecture, Sichuan Agricultural University, Chengdu 611130, China | | | ZHAO Yin | College of Landscape Architecture, Sichuan Agricultural University, Chengdu 611130, China | | | JIA Yin | College of Landscape Architecture, Sichuan Agricultural University, Chengdu 611130, China | | | JIANG Bei-bei | College of Landscape Architecture, Sichuan Agricultural University, Chengdu 611130, China | | | ZHANG Lu | College of Landscape Architecture, Sichuan Agricultural University, Chengdu 611130, China | | | XU Qian | College of Landscape Architecture, Sichuan Agricultural University, Chengdu 611130, China | | | LIU Si-li | College of Landscape Architecture, Sichuan Agricultural University, Chengdu 611130, China | | | WANG Kai-lu | College of Landscape Architecture, Sichuan Agricultural University, Chengdu 611130, China | | | ZENG Yong | College of Landscape Architecture, Sichuan Agricultural University, Chengdu 611130, China | |
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| Abstract: |
| To study and compare the effects of cadmium(Cd) stress on plant photosynthetic physiology and chlorophyll, Cd hyperaccumulators of Solanum nigrum and Solanum americanum were selected as materials. A water culture experiment was conducted to observe and analyze their growth and gas exchange parameters, as well as their chlorophyll contents and chlorophyll fluorescence parameters under different Cd levels(0, 20, 80, and 320 μmol·L-1). The results showed that S. nigrum and S. americanum possessed different Cd tolerance abilities. The growth of S. americanum was inhibited when Cd content ≥ 20 μmol·L-1(P<0.05)as its morphological indicators, biomass, chlorophyll content, net photosynthetic rate(Pn), stomatal conductance(Gs), transpiration rate(Ts), the maximum photochemical efficiency(Fv/Fm), and PS Ⅱ potential activity(Fv/Fo) were all significantly decreased under increasing Cd stress compared with those of the control. However, the Fo and Chla/Chlb values of S. americanum increased under Cd stress. Cadmium could destroy the chloroplast structure in S. americanum and increase PSⅡ damage at Cd ≥ 80 μmol·L-1. S. nigrum growth was inhibited when Cd content was >80 μmol·L-1, and all S. nigrum indices decreased with increasing Cd stress(P<0.05)but with smaller reductions than those observed for S. americanum indices. Furthermore, Cd stress inhibited energy transfer efficiency to a greater extent than light energy conversion efficiency. In addition, photosynthesis was mainly influenced by stomatal factors when Cd stress was 20 μmol·L-1, whereas it was affected by non-stomatal factors when Cd stress was 80~320 μmol·L-1. In summary, Cd stress showed more obvious inhibitory effects on the growth and photosynthesis of S. americanum than on those of S. nigrum. The reductions in photosynthesis observed in the two species were the result of the combined effects of stomatal factors and non-stomatal factors. The present study further demonstrated that Cd tolerance was stronger in S. nigrum than in S. americanum in terms of photosynthetic physiology and chlorophyll fluorescence characteristics. |
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