Nutrient uptake and assimilation in fragrant rosewood (Dalbergia odorifera T.C. Chen) seedlings in growing media with un-composted spent mushroom residue.

The purpose of this study was to detect nutrient uptake and assimilation in woody plants subjected to growing media with some peat replaced by spent mushroom residue (SMR). Fragrant rosewood (Dalbergia odorifera T.C. Chen) seedlings were cultured in five types of growing media with SMR and peat in volumetric proportions of 0% (control), 25%, 50%, 75%, and 100%. With the increase of SMR proportion, ammonium- and nitrate-nitrogen (N) concentrations declined but available phosphorus (P) concentration and electrical conductance both increased. Seedlings in the full SMR substrates showed obvious mortality. Seedlings in substrates with SMR in proportions higher than 25% showed symptoms of excessive N and P toxicities. The utilization efficiency for P was highest in the 25% SMR growing-media. Mineral N in substrates had a positive relationship with growth and biomass but not with glutamine synthetase activity. Available P was negatively related with acid phosphatase activity in both leaves and roots. Un-composted SMR can replace 25% of peat in growing media for fragrant rosewood seedlings, benefitting P uptake and assimilation.