Abstract
The article presents the results of a study of drought tolerance of two species and two interspecific hybrids (alloplasmic lines) of wheat according to the anatomy and photosynthetic activity of leafblades under conditions of induced osmotic stress. The negative effect of drought on the leaf anatomicalstructure and on such photosynthetic parameters as the maximum quantum yield of photosynthesis ofphotosystem II (Fv/Fm) and a change in the electron transport through photosystem II (ETR) was shown.The quantum yield of controlled energy dissipation (Y (NPQ)) and the quantum efficiency of unregulatedenergy dissipation of PSII (Y (NO)) were experimentally determined. It was shown that the increase orpreservation of the size of the protective and mechanical tissues of the leaf unchanged under stress canserve as criteria for the selection of drought-resistant forms of wheat in the early stages of ontogenesis.It was clearly reflected that a decrease in the ETR level during stress can be associated with activationof non-photochemical quenching mechanisms, and their combination were characterizing the low resistance of the studied form to drought. A high level of resistance to drought was indicated by a minimaldecrease in the parameter Y (NPQ) under stress. As a result of the study, it was noted that the D-d-05bline can be considered more stable, and the D-42-05 line – less resistant to drought. A different degreeof drought tolerance of the studied lines allowed us to suggest that the combination of nucleus and cytoplasm obtained from interspecific crosses can contribute to both increasing and lowering the important physiological parameters of drought tolerance and photosynthetic activity. This implies the need to continue research involving molecular genetic analysis.Key words: drought tolerance, leaf, seedlings, wheat, photosynthesis