Phenolic compounds as one of the biochemical indicators of frost resistance of the genus Cynoxylon L. representatives in the conditions of Forest-Steppe of Ukraine

The study of phenolic compounds in shoots of the genus Cynoxylon L. representatives due to the sharp fluctuations of temperatures during winter dormancy. Analysis of the obtained experimental data showed that the species and forms of the genus Cynoxylon differ significantly in content of phenolic compounds in the period of sharp fluctuations of temperatures. But, the histogram depending of the content of phenolic compounds from average daily temperatures of all investigated species has similarities and differences. It is established that Cynoxylon japonica (Siebold & Zucc.) Nakai has a larger amplitude in the content of phenols in the temperature change unlike Cynoxylon florida Raf., where the change in the accumulation of phenols occurs more smoothly. C. japonica responds to more short-term changes in temperature contrast C. florida, where the changes of accumulation of phenolic compounds occur only during prolonged cold snaps, or warming. All this indicates a higher frost resistance C. japonica in relation to C. florida.