ROMANIAN AGRICULTURAL RESEARCH, no.38, pp.1-10, 2021 (SCI-Expanded)
Cadmium (Cd), a non-essential heavy metal that cannot be naturally degraded, causes toxicity for plant,
animal and human due to the easy incorporation into the food chain with its high mobility in soil-plant system.
Tobacco (Nicotiana tabacum L.) contrary to other crops, has ability to absorb and accumulate high
concentration of Cd in the leaves without showing phytotoxicity symptom. The purpose of this study was to
investigate the effects of zinc (Zn) applications on chemical composition of tobacco leaves under increased doses
of Cd under greenhouse conditions. The experimental layout was randomized plots with three replicates, and
two different tobacco genotypes (Birlik-124, Xanthi-81) were used as the plant material of the experiment.
Plant growing medium was a Zn-deficient calcareous soil, and plants were treated with increasing Cd (0, 2.5,
5.0 and 10 mg kg-1
soil) and Zn (0 and 5 mg kg-1
soil) doses. The tobacco leaves were harvested in three times
and all harvested leaves were dried under sunlight. The leaf samples were analyzed for Cd and Zn
concentrations, nicotine, glucose, fructose, chlorogenic and rutin contents. The Cd concentration from leaves of
both tobacco genotypes significantly increased (P<0.05) with the increase in Cd application rate, but the
increase in Cd concentration decreased with Zn application. Application of increased Cd doses significantly
(P<0.05) increased or decreased the nicotine content of leaves, while Zn application caused a significant
increase in nicotine contents of both tobacco genotypes. The nicotine content in Birlik-124 and Xanthi-81
genotypes was 0.41 and 0.48% in control plants (Zn0), and increased up to 0.54% in plants treated with zinc
(Zn5 variant). Similar to the nicotine content of both tobacco genotypes, the responses of both genotypes to Cd
stress was different form each other, however, Zn application under Cd toxicity caused an increase in sugar
synthesis of tobacco varieties. The results revealed that Zn plays an important role in the alleviating the
negative effects of Cd stress in tobacco plants.