Some morphological, physiological and biochemical characteristics of wheat seedling Triticum aestivum L. organs after high-temperature treatment

Plants as sessile organisms are exposed to persistently changing stress factors. Heat stress adversely affects plant growth and development and induces oxidative stress in plants. To understand the effect of high-temperature stress on plant growth and development, it is necessary to study the physiology and morphology of whole plants and their organs. The oxidative stress level was assessed by increased production of lipid peroxidation (LP) products, such as malondialdehyde (MDA) and conjugated dienes (CD), and cellular membrane permeability, as evaluated by electrolyte leakage (EL) in different wheat (Triticum aestivum cv. Harmonija) organs after 24-hour high-temperature (42 °C) treatment. Measurements of relative water content (RWC) in leaf tissues were used to assess water deficits in plants. High-temperature treatment had no effects on RWC in the root, but reduced RWC in the coleoptile at all investigated stages of seedling development and in the first leaf (p ≤ 0.01) at the late stages of development. A 24-h high-temperature exposure completely inhibited the growth of the first leaf and root (p ≤ 0.001). LP significantly increased in the coleoptiles of wheat seedlings due to high temperature, but in contrast LP in the root was similar to control at all investigated stages of development. A significant increase of LP products (p ≤ 0.01) was observed in the first leaf at the late stages of wheat seedling development. Such elevated level of LP led to increase of cellular membrane permeability. 24-h high temperature results in the desiccation of the first leaf and coleoptile. Obviously the root of wheat seedlings is less sensitive to heat stress than the first leaf and coleoptiles. The study revealed that specific effects of high temperature on the root result in increase of electrolyte leakage, but high temperature hardly affects lipid peroxidation processes.