Interactions of copper and phosphorus in accessions of Pfaffia glomerata: effect on growth and yield of β-ecdysone

The increase in copper content (Cu) in soil by antropogenic actions can cause severe damage to plants. This study aimed to evaluate the effects of increasing levels of Cu and phosphorus (P) on the growth and production of β-ecdysone of two accessions (JB e BRA) of Pfaffia glomerata. The experiment was carried out under greenhouse conditions in pots containing 4.0 kg of an Ultisol soil with four Cu levels (control, 20, 40 and 80 mg/kg) and three P levels (10, 60 and 120 mg/kg) for 90 days. Root and leaf Cu concentration in JB accession linearly decreased with increasing Cu levels in the presence of 60 mg P/kg soil. On the other hand, in general, at 10 and 120 mg P/kg soil, root and leaf Cu concentration increased with increasing Cu levels. The increase in soil Cu availability reduced the P concentration in leaves. In the presence of 60 mg P/kg soil, total dry matter in JB accession linearly increased with increasing Cu levels. The maximum total dry mass in BRA accession occurred at 40 mg Cu/kg and 10 mg P/kg of soil. The addition of P and Cu only influenced the root β-ecdysone accumulation in JB accession, where at 60 mg P/kg soil it linearly increased with increasing Cu levels. Therefore, both P. glomerata accessions showed significant variability for plant biomass production and root β-ecdysone accumulation in relation to changes in soil Cu and P levels, but JB accession was more responsive.