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Due to the environment pollution by cadmium (Cd) near industrial metallurgic factories and the widespread use of phosphorus fertilizers, the problem of toxic Cd effect on plants is well discussed by many authors, but the phytotoxicity of Cd under iron (Fe) deficiency stress has not been sufficiently studied. The aim of the work was to study comprehensively the effect of Cd under Fe deficiency conditions on physiological, biochemical, and anatomical parameters of rice varieties, to identify varietal differences in plant response to the effect of double stress. Relative resistance and sensitivity to the joint effect of Cd and Fe deficiency stress rice varieties have been identified. Double stress decreased a linear growth and biomass accumulation of roots and shoots (by 36-50% and 33-46% and 32-56% and 32-48%, accordingly), content of photosynthetic pigments (Chla, Chlb, and carotenoids by 36-51%, 32-47%, and 64-78%, accordingly), and relative water content (by 18-26%). Proline content increased by 28-103% in all rice varieties, but to a lesser extent in sensitive varieties. The thickness of the lower and upper epidermis and the diameter of vascular bundles of leaves decreased by 18-50%, 46-60%, and 13-48%, accordingly. The thickness of the root endodermis and exodermis and diameter of the central cylinder mainly decreased. The thickness of the exodermis increased slightly by 7%, and the diameter of the central cylinder remained at the control level in resistant Madina variety while in sensitive Chapsari variety, these indicators decreased significantly by 50 and 45%, accordingly. Thus, the aggravation of adverse effect of Cd under Fe deficiency conditions and the varietal specificity of plants’ response to double stress were shown. It creates the need for further study of these rice varieties using Fe to identify mechanisms for reducing the toxic effect of Cd on plants as well as the study of Fe and Cd transporter genes at the molecular level.

The purpose of our study was the identification of spring wheat varieties resistant to cadmium, a priority pollutant in the East Kazakhstan region. The experiments were carried out in the condition of model environmental pollution on 14-day sprouts of various spring wheat varieties, that were grown on a nutrient mixture, containing 0.1 mM of CaSO4 and Cd ions at a concentration of 40 mg/l. Screening of spring wheat varieties under the conditions of the model experiment made it possible to identify resistant and sensitive genotypes. In terms of growth and accumulation of cadmium in the aboveground organs, the most resistant to cadmium spring wheat varieties are Samal and Kaiyr, the least resistant are the varieties Lutescens and Zhenis. In terms of growth and accumulation of cadmium in the roots, the most resistant varieties of spring wheat were Kazakhstan-15 and Kazakhstan Early, the most unstablethe variety Lutescens. Chlorophyll a is more sensitive to the action of cadmium ions than chlorophyll в. Cadmium-resistant varieties can be used in field studies of soil contamination with cadmium to identify promising forms that combine metal resistance with high yield and resistance to weather conditions.