G. Ouzounidou et Ha. Constantinidou, Changes in growth and physiology of tobacco and cotton under Ag exposure and recovery: Are they of direct or indirect nature?, ARCH ENV C, 37(4), 1999, pp. 480-487
Citations number
30
Categorie Soggetti
Environment/Ecology,"Pharmacology & Toxicology
Journal title
ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY
Responses of tobacco and cotton seedlings to two chemical farms of Ag at va
rious concentrations were studied. Cotton exhibited higher resistance than
tobacco to Ag. The application of 1 mu g L-1 Ag, as AgI or AgNO3, induced n
o toxicity symptoms in the growth and photosynthesis of cotton. However, th
e corresponding concentration negatively affected the growth and physiology
of tobacco. On exposure to higher Ag concentrations (10(3) and 5 X 10(3) m
u g L-1 as AgNO3), root growth and concentrations of Ca, Mg, K, and Fe were
significantly depressed, whereas concomitant Ag accumulation, especially i
n roots, was increased in both species. The loss of nutrients and chlorophy
ll was associated with disturbances in photosynthetic function. Because the
re was no apparent change in Fv/Fm, there is a possibility that the faster
rise time was due to an increase in LHC size to the PSII reaction centers.
The decreased Fv/Fo reflects the inactivation of chlorophyll associated wit
h the PSII reaction center. Stomatal conductance was decreased less than th
e CO2 assimilation, possibly due to the direct and/or indirect effects of A
g ions on stomatal guard cells. After the plants were transferred from the
highest Ag concentration to a nutrient solution, recovery of tobacco, cotto
n morphology, and physiology were observed.