title: Interactions between drought, ABA application and supplemental UV-B in Populus yunnanensis.
abstract: To test whether drought and ABA application alter the effects of enhanced UV-B on the growth and biomass allocation of Populus yunnanensis Dode, cuttings were grown in pots at two ABA levels, two watering regimes and two UV-B levels for one growth season. Exposure to enhanced UV-B radiation significantly decreased plant growth and photosynthesis under well-watered conditions, but these effects were obscured by drought, which alone caused growth reduction. Drought may contribute to masking the effects of UV-B radiation. The accumulation of UV-B absorbing compounds and the increase of the ABA content induced by drought could reduce the effectiveness of UV-B radiation. ABA application did not have large direct effects on biomass accumulation and allocation. Evidence for interactions between UV-B and ABA was detected for only a few measured traits. Therefore, there was little evidence to support a pivotal role for ABA in regulating a centralized whole plant response to enhanced UV-B. Yet, we recorded an ABA-induced decrease in stomatal conductance (g(s)) and increase in UV-B absorbing compounds and carbon isotope composition (delta(13)C) in response to enhanced UV-B. The allometric analysis revealed that regression models between root and shoot biomass in response to enhanced UV-B are different for plants under well-watered and drought conditions. Enhanced UV-B led to a significant displacement of the allometric regression line under well-watered condition, while allometric trajectories for both UV-B regimes did not differ significantly under drought condition.
authors.affiliation: Center for Ecological Studies, Chengdu Institute of Biology, Chinese Academy of Sciences, PO Box 416, Chengdu 610041, China.
authors.forename: Baoli
authors.initials: B
authors.lastname: Duan
authors.forename: Zuying
authors.initials: Z
authors.lastname: Xuan
authors.forename: Xiaolu
authors.initials: X
authors.lastname: Zhang
authors.forename: Helena
authors.initials: H
authors.lastname: Korpelainen
authors.forename: Chunyang
authors.initials: C
authors.lastname: Li
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D000222:Adaptation, Physiological / Q000187:drug effects / Q000528:radiation effects; D018533:Biomass; D002244:Carbon / Q000378:metabolism; D002247:Carbon Isotopes / Q000378:metabolism; D055864:Droughts; D009584:Nitrogen / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000254:growth & development / Q000378:metabolism; D032107:Populus / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D012044:Regression Analysis; D014466:Ultraviolet Rays
chemical_list: D002247:Carbon Isotopes; D010937:Plant Growth Regulators; D000040:Abscisic Acid; D002244:Carbon; D009584:Nitrogen