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Abstract
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High concentrations of heavy metals disrupt the metabolic processes of plant growth and even cause plant
death. Plants show different tolerance thresholds to heavy metals, therefore, the effect of different
concentrations of heavy metals zinc (Zn) and cadmium (Cd) (zero, 2 and 4 mgL
-1
) in two varieties of
spinach (common seed and Thorny seeds) on some morphological, physiological traits and content of the
elements were examined in the factorial experiment based on a completely randomized design with three
replications. The results showed that some morphological traits of the plant are affected by metals and
cultivar type independently, so that the lowest wet weight of leaves and plant height was observed in four
mgL
-1
of Cd treatment and the highest amount of these two traits was observed in two mgL
-1
of Zn. The
highest dry weight of the plant was recorded in the thorny cultivar and the highest plant height was
recorded in the normal seed cultivar. The interaction of the type of cultivar and heavy metals was
significant in some physiological traits such as soluble solids content, catalase content, and superoxide
dismutase. The highest activity of catalase enzyme was observed in the treatment of 2 mgL
-1
of Cd in
normal seeds and the highest amount of superoxide dismutase was observed in the treatment of 4 mgL
-1
of
Zn and 2 mgL
-1
of Cd in normal seeds. Zinc metal up to 2 mgL
-1
increased the growth and development
of spinach, but more than this amount, like cadmium metal, reduced yield and increased the amount of
antioxidant enzymes. All content of the measured elements showed a significant interaction. As the
cadmium increased, the plant's uptake of the Ca, K, Zn, Mn and Mg decreased, so that the lowest amount
of all the elements measured in four mgL
-1
of Cd was observed in thorny seeds. The results of
determining the biological concentration in this experiment showed that the cadmium content of thorny
and common spinach leaves varied between 145 and 167 mgKg
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