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Inhibition of photosynthesis and transpiration in relation to mercury‐induced root damage in spruce seedlings
Author(s) -
Godbold Douglas L.,
Hüttermann Aloys
Publication year - 1988
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1988.tb00631.x
Subject(s) - transpiration , photosynthesis , picea abies , chemistry , chlorophyll , botany , horticulture , nutrient , transpiration stream , respiration , environmental chemistry , biology , biochemistry , organic chemistry
Spruce seedlings [ Picea abies (L.) Karst.] were exposed in nutrient solutions to a range of concentrations of HgCl 2 and CH 3 HgCl for 7 weeks. The mineral, chlorophyll and water contents of the needles, and dry weights of root and needles were then estimated. The rates of photosynthesis, transpiration and dark respiration of the intact plants were determined using a Li‐cor portable photosynthesis‐measuring system. CO 2 uptake decreased as the supply of both forms of Hg increased. Rates of transpiration were significantly reduced only after exposure to CH 3 HgCl. Similar concentrations of Hg were found in needles independent of the form of Hg supplied. Decreased rates of CO 2 uptake at 100 n M HgCl 2 and 1 n M CH 3 HgCl could be explained by lower levels of chlorophyll, and by lower levels of chlorophyll and closed stomata at all other CH 3 HgCl concentrations. Only at 1000 n M HgCl 2 were other photosynthetic parameters affected. Decreased rates of transpiration and the lower chlorophyll levels in the needles did not appear to be due to the direct action of Hg, but rather to root damage that leads to a decrease in water supply and nutrient levels in the needles.