Combined effects of heavy metals and drought in the early stages of sunflower ontogenesis

Orenburg State University, Orenburg, Russia

^* Corresponding author: nazarova-1989@yandex.ru

Abstract

The paper presents the results of a study on the effect of various soil moisture supply conditions and increasing concentrations of the most common agricultural soil pollutants - cadmium (Cd) and lead (Pb) on the growth of Helianthus annuus L. 'Poseidon 625' seedlings. It was found that Cd absorption by seedlings under soil moisture deficiency conditions increases compared to sufficient watering conditions, while Pb absorption decreases. It was determined that simulating drought conditions with an osmotic solution (7.4% sucrose) prevents the growth of the aboveground part of seedlings and activates the growth of the root system. It was shown that under the influence of various cadmium concentrations in the soil, the development of the root system of 8-day-old seedlings is blocked, but active development of adventitious roots of the "goose foot" type is observed, which contributes to the adsorption and accumulation of Cd²⁺ in the phytomass. It was found that maximum concentrations of lead suppress the growth of both the main and adventitious roots of sunflower seedlings and simultaneously stimulate the growth of their above-ground part, which probably indicates the activation of the storage function of the stem, as the next line of defense of seedlings from the damaging effects of combined stress.