The Role of Phytohormones in the Regulation of the Tolerance of Wheat, Rye, and Triticale Seeds to the Effect of Elevated Temperatures during Germination

The dynamics of changes in the content of phytohormones, abscisic (ABA), and indole-3-acidic (IAA) acids at early stages of the germination of wheat, rye, and triticale (a hybrid of wheat and rye) seeds at a normal temperature (22 degrees C) and during short heat shock (40 degrees C) was studied. In dry wheat and triticale germs, free and conjugate indole-3-acidic and abscisic acids were present, although conjugates prevailed. The effect of elevated temperatures on germs at different stages of swelling and germination induced rapid changes in the levels of hormones. Changes in the ratio of these acids in wheat and triticale germs exposed to short heat shock were revealed. These changes may be associated with self-regulation and hormone transition to an inactive state. The dependence of growth processes on the IAA/ABA ratio during a short heat shock was indicated. The processes preceding seedling emergence and active growth were shown to differ in temperature sensitivity.