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KMID : 1024520150240111501
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Journal of the Environmental Sciences
2015 Volume.24 No. 11 p.1501 ~ p.1511
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Copper and Zinc Uptake Capacity of a Sorghum-Sudangrass Hybrid Selected for in situ Phytoremediation of Soils Polluted by Heavy Metals
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Oh Soon-Ja
Koh Seok-Chan
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Abstract
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As essential trace elements, copper and zinc play important roles in many physiological events in plants. In excess,
however, these elements can limit plant growth. This study selected a heavy metal-tolerant plant by analyzing seed
germination and biomass of alfalfa (Medicago sativa), canola (Brassica campestris subsp. napus var. nippo-oleifera), Chinese corn (Setaria italica), and a sorghum-sudangrass hybrid (Sorghum bicolor × S. sudanense), and determined heavy metal uptake capacity by analyzing biomass, chlorophyll a fluorescence, and heavy metal contents under high external copper or zinc levels. The seed germination rate and biomass of the sorghum-sudangrass hybrid were higher under copper or zinc stress compared to the other three plants. The plant biomass and photosynthetic pigment contents of the sorghum-sudangrass hybrid seedlings were less vulnerable under low levels of heavy metals (≤ 50 ppm copper or ≤ 400 ppm zinc). The maximum quantum yield of PSII (Fv/Fm) and the maximum primary yield of PSII (Fv/Fo) decreased with increasing copper or zinc levels.
Under high copper levels, the decline in Fv/Fm was caused only by the decline in Fm, and was accompanied by an increase in non-photochemical quenching (NPQ). The Fv/Fm declined under high levels of zinc due to both a decrease in the maximum fluorescence (Fm) and an increase in the initial fluorescence (Fo), and this was accompanied by a marked decrease in photochemical quenching (qP), but not by an increase in NPQ. Accumulations of copper and zinc were found in both aboveand below-ground parts of plants, but were greater in the below-ground parts. The uptake capacity of the sorghum-sudangrass hybrid for copper and zinc reached 4459.1 mg/kg under 400 ppm copper and 9028.5 mg/kg under 1600 ppm zinc. Our results indicate that the sorghum-sudangrass hybrid contributes to the in situ phytoremediation of copper or zinc polluted soils due to its high biomass yield.
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KEYWORD
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Biomass, Chlorophyll a fluorescence, Copper, Photosynthetic pigments, Seed germination, Sorghum-sudangrass hybrid, Zinc
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