Tree water status fluctuations directly affecting the xylem cell morphogenesis of drought‑stressed Scots pine trees

0520553 - ÚVGZ 2020 CZ eng A - Abstract
Fajstavr, Marek - Horáček, Petr - Giagli, K. - Vavrčík, H. - Gryc, V. - Stojanović, Marko - Urban, J.
Tree water status fluctuations directly affecting the xylem cell morphogenesis of drought‑stressed Scots pine trees.
EuroDendro 2019. Brno: Mendel University in Brno, 2019 - (Gryc, V.; Giagli, K.; Kolář, T.; Koňasová, E.; Rybníček, M.; Vavrčík, H.). s. 48-49. ISBN 978-80-7509-676-0.
[EuroDendro 2019. 09.09.2019-13.09.2019, Brno]
R&D Projects: GA MŠMT(CZ) LO1415
Institutional support: RVO:86652079
Keywords : Pinus sylvestris * morphogenesis * tracheid * water status * drough
OECD category: Forestry

Major current problem in the terrestrial temperate forests is the long‑lasting drought periods combined with heat waves negatively affecting the tree water status. Very few information still exists on the acclimation processes of drought‑suffering Scots pine trees. We analysed the morphogenesis rate of differentiating tracheids during summer drought for three consecutive growing seasons (2014–2016). Xylem tissues were micro‑cored (Trephor tool) from the tree stems in weekly intervals. The microcore samples were used for preparing permanent microscopic slides (cross sections) to analyse the cambial activity, duration and rate of tracheid morphogenesis. During all examined years, we recorded summer drought episodes, where the value of the daily soil water potential dropped below –1 MPa and daily sap flow dropped under 5 kg∙day–1, resulting to cambial latency (reduced number of dividing cells). After improved tree water status the cambial division was reactivated and hence, the xylem cells began to form again. This resulted to formation of earlywood‑like tracheids appearing inside the latewood zone (intra‑annual density fluctuation) reflected also by the rate of cell enlargement and cell‑wall thickening. The longest and most severe summer drought period in 2015 ceased the cambial activity significant earlier (in mid‑August) and the latewood tracheids spent significant shorter time in both cell enlargement and cell wall thickening phases which resulted to 32% narrower tracheids with 34% thinner cell walls compared with the other years. Thus we concluded that the fluctuations of tree water status had a direct impact on the cell radial dimensions and mainly, cell‑wall thickness.
Permanent Link: http://hdl.handle.net/11104/0305230