Current uptake of 15N –labeled ammonium and nitrate in flooded and non-flooded black spruce and tamarack seedlings.

• Author(s) / Creator(s)

  • Macdonald, S. Ellen
  • Islam, M. Anisul

• We investigated the effects of flooding for three weeks on physiological responses and uptake of NH4+ and NO3- by black spruce (Picea mariana (Mill.) BSP.) and tamarack (Larix laricina (Du Roi) K. Koch) seedlings fertilized with labeled (15NH4)2SO4 or K15NO3 in a growth chamber experiment. Flooding reduced photosynthesis (A), transpiration (E), water use efficiency (WUE), and current uptake of NH4+ and NO3- in both species. Under flooding, there were no significant differences between the two species in uptake of either NH4+ or NO3- at the whole-plant level but black spruce had higher translocation of NH4+ to the shoots than did tamarack. Under non-flooded conditions, black spruce seedlings exhibited higher uptake of both NH4+ and NO3- than did tamarack and demonstrated preferential uptake of NH4+ (19. 7 mg g-1dw) over NO3- (12.3 mg g-1dw after three weeks). In contrast, non-flooded tamarack seedlings had equal uptake of NH4+ (4.96 mg g-1dw) and NO3- (4.97 mg g-1dw). We hypothesize that the ability of tamarack to equally exploit both 15NH4+ and 15NO3- would confer an advantage over black spruce, when faced with limitations in the availability of different forms of soil nitrogen.

• Date created

  2009

• Subjects / Keywords

  • Gas exchange
  • Flooding
  • Nitrate
  • Ammonium
  • Photosynthesis

• Type of Item

  Article (Published)

• DOI

  https://doi.org/10.7939/R30863784

• License

  © 2009 Annals of Forest Science. This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.