| dc.description.abstract | The purpose of this study was to quantify the effects of heavy metals on pigments
and photosynthesis in four and a half month old black spruce (Picea mariana (Mill.)
B.S.P.) seedlings. Photosynthetic pigment analysis by HPLC and reflectance red edge
methods were compared to chi a fluorescence and net oxygen evolution measurements to
assess their effectiveness in diagnosing plant stress. Copper, zinc and cadmium were
applied as 0, 10 and 20 mM Cu(N03)2, Zn (N03)2 and Cd(N03)2, for 214 weeks.
Response to the treatments was examined by measuring pigment content, reflectance red
edge, (see document) net oxygen evolution, net water content and needle element content. No
treatment differences were found for pigment content or red edge. In contrast, (see document) of
seedlings treated with 20 mM Cd was significantly lower than all other treatments and net
oxygen evolution decreased m metal-treated seedlings compared to untreated control
seedlings. Net water content did not differ between treatments. Needle element content
did not change, except for increases m Cu, Zn and Cd in the seedlings treated with these
elements. It was concluded that pigment content was unaffected by the treatments but
that photosynthetic efficiency (i.e. oxygen evolved) decreased. Possible explanations
include inhibition of enzyme activity by Cu2+, Zn2+ and Cd2+, or overloading of defense
mechanisms, such as phytochelatins. The use of HPLC analysis of pigments and remote
spectroradiometry may prove useful in assessing seedling quality. | |
