Effects of waterlogged soil on N-uptake by flood tolerant and sensitive containerised tree seedlings

Abstract

ABSTRACTThis study was conducted to determine changes in nitrogen concentrations in urban tropical tree species across short-and long-term flooding with a week of recovery. The roots of Pouteria obovata (flood-tolerant), Albizia saman (moderately flood-tolerant) and Peltophorum pterocarpum (flood-sensitive) were exposed to different flooding treatments (5 and 21 days). N uptake, amino acid, protein, chlorophyll concentrations, respiration and photosynthesis were measured. Differences between the moderately flood-tolerant and flood-sensitive species were observed only in the uptake rates of nitrate (NO3–) and ammonia (NH4+) and protein concentrations. Short-term (5 days) flooding decreased N concentrations but recovery was observed after long-term (21 d) flooding with the exception of the flood-sensitive species. Amino acids in the foliage across all three species were found to have significantly increased with short-term flooding but this increase was short-lived as a decline was observed following long-term flooding. Amino acids (in the roots) and chlorophyll concentrations indicated that P. obovata was more flood-tolerant and had greater recovery potential than the other two species. Photosynthesis and transpiration were significantly decreased in all species with long-term flooding, but recovery occurred after a week. The results confirmed that flooding can impact on nitrogen uptake and related protein and pigment concentrations in the urban tropical trees investigated here.