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The metabolic activity of phytohormones and the accumulation of carbohydrates affect the reactivation of the cambial zone and the radial increment of woody plants. We aimed to monitor the dynamics of indole-3-acetic acid (IAA) concentration and amounts of soluble carbohydrates during xylem and phloem formation of one growing season (2015). Six sample trees of Scots pine (Pinus sylvestris L.), aged 80 years on average, growing in the Sobešice research site (404 m a.s.l.) in the Czech Republic were selected. We obtained microcore samples at weekly intervals by the Trephor tool method for cell formation analysis and spectrophotometric determination of IAA and soluble carbohydrate contents. We found that time of the highest concentration of IAA (last week of April) coincided with time of the maximum number of cells in the cambial zone and highest expansion of the cell enlargement stage. When the IAA concentration was too low to be measured, latewood tracheids started to form, and late phloem sieve cell formation ceased. The highest concentration of soluble carbohydrates was 200.40 ± 21.6 µg GLU per sample (May 14). This coincided with the fastest weekly xylem cell increment. This research shows that IAA and soluble carbohydrate dynamics directly affects xylem and phloem formation. [ABSTRACT FROM AUTHOR]

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Brassinosteroids act favourably in the conditions unexpected stresses infields as e.g. low or extreme temperatures, dry weather, poor soils, etc. By their chemical structure they are steroid phytohormones known from 2988. Their activity consists of the control mechanism of other known phytohormones especially auxins and gibberelins. Small plot trials took its place at the Czech University of Life Sciences Prague in which we tested the impact of brassinosteroids on the yield and technological quality of sugar beet and on the comparison of their activity, which was analyzed by the photosynthesis and its energy balance and yielding in the vegetative period. Native 24-epi, present in some wild plants, was compared to virtually more efficient derivatives (A, B) made by the Institute of Organic Chemistry and Biochemistry of the Academy of Sciences of the Czech Republic and to control. [ABSTRACT FROM AUTHOR]