[Diurnal cycles of endogenous phytohormones in barley].

We have studied diurnal courses of the free forms of phytohormones (abscisic acid, gibberellins, cytokinins, indolylacetic acid, and ethylene) in leaves of the spring variety of barley (Hordeum vulgare L.), cultivars Zazerskii 85 and Moskovskii 2 in vegetation experiments. The phytohormones were analyzed by gas-liquid chromatography, immunoenzyme assays, and bioassays, using unfractionated plant material. Assays were conducted over a period of 22-24 h, every 2 h, during the phases of formation of the third leaf and tillering; for indolylacetic acid, assays were also conducted during the phases of booting and the beginning of flowering. It has been demonstrated that the ratio of phytohormones in the plant shows continuing changes over 24 h, and the rate of change of this ratio is extremely high. There is a certain functional relationship between changes in the hormonal balance and the accompanying growth processes. The proportion between phytohormones is also significantly affected by such environmental factors as temperature, air humidity, and lighting.