title: Role of boron in drought resistance in Norway spruce (Picea abies) seedlings.
abstract: Norway spruce (Picea abies (L.) Karst.) seedlings fertilized with boron (B) at three rates were grown in a 3:7 mix of forest humus and quartz sand for 18 weeks. Half of the seedlings were not watered during the last 9 days of the experiment (drought treatment). The role of B in drought resistance was assessed by comparing the effects of seedling internal B concentration on the water relations, photosynthesis, growth and nutrition of well-watered and drought-treated seedlings. At the end of the drought treatment, needle B concentrations were 7.0 mg x kg(-1) at the lowest B supply rate and 17.5 and 23.5 mg x kg(-1), respectively, at the higher supply rates. Seedlings at the lowest B supply rate had fewer root tips and mycorrhizas than seedlings at the higher B supply rates. Drought treatment had a more pronounced effect on the water relations and net photosynthetic rate of seedlings than B treatment. Although seedlings at the higher B supply rates lost water more rapidly than seedlings at the low B supply rate-leading to faster stomatal closure and decreased photosynthesis-drought did not affect their final height, whereas drought reduced height growth of seedlings at the low B supply rate.
authors.affiliation: University of Joensuu, Faculty of Forestry, P.O. Box 111, 80101 Joensuu, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Möttönen
authors.forename: P J
authors.initials: PJ
authors.lastname: Aphalo
authors.forename: T
authors.initials: T
authors.lastname: Lehto
mesh_terms: D001895:Boron / Q000032:analysis / Q000502:physiology*; D010788:Photosynthesis / Q000502:physiology; D028222:Picea / Q000737:chemistry / Q000254:growth & development / Q000502:physiology*; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000502:physiology; D018520:Plant Shoots / Q000737:chemistry; D012987:Soil; D014197:Trees / Q000737:chemistry / Q000254:growth & development / Q000502:physiology*; D014867:Water
chemical_list: D012987:Soil; D014867:Water; D001895:Boron