title: Seasonal change in the drought response of wood cell development in poplar.
abstract: Field-grown poplar trees (Populus nigra L. x P. maximowiczii Henry, clone Kamabuchi) were exposed to severe drought twice during the growing season to evaluate the impact on wood cell development. The drought treatment caused a reduction in leaf water potential, leaf wilting and a decreased concentration of osmotically active solutes in the cambial zone. Drought-induced changes in the anatomy of developing xylem cells were examined in stem sections and macerated wood samples. In early summer, drought significantly reduced the length and cross-sectional area of newly formed fibers, whereas no such effects were observed in late summer. In well-watered trees, fiber cross-sectional area declined between early and late summer. Similarly, drought reduced the cross-sectional area of vessel elements in early summer but not in late summer, whereas in both control and drought-treated trees, the cross-sectional area of vessel elements decreased between early and late summer. The vessel area to xylem area ratio was unaffected by drought because the drought-induced decrease in vessel size was matched by an increase in the number of newly formed vessel cells. In contrast to its effect in early summer, late-summer drought had no significant effect on fiber and vessel cell development, indicating that sensitivity of wood cell development to drought varies seasonally.
authors.affiliation: Fachgebiet Angewandte Holzbiologie, Technische Universität München, Germany. arend@wzw.tum.de
authors.forename: Matthias
authors.initials: M
authors.lastname: Arend
authors.forename: Jörg
authors.initials: J
authors.lastname: Fromm
mesh_terms: D004190:Disasters; D018514:Plant Structures / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D032107:Populus / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism*; D012621:Seasons; D014867:Water / Q000378:metabolism; D014934:Wood / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D052584:Xylem / Q000166:cytology / Q000254:growth & development / Q000378:metabolism
chemical_list: D014867:Water