TY - JOUR
T1 - Poor regulation of phosphorus uptake and rhizosphere carboxylates in three phosphorus-hyperaccumulating species of Ptilotus
AU - Suriyagoda, Lalith B.D.
AU - Tibbett, M.
AU - Edmonds-Tibbett, T.
AU - Cawthray, Greg R.
AU - Ryan, Megan H.
PY - 2016/5/1
Y1 - 2016/5/1
N2 - © 2015, Springer International Publishing Switzerland. Background and aims: Ptilotus polystachyus occurs in phosphorus (P) – poor soils, but can hyperaccumulate P without toxicity. We examined, in P-poor soils, P accumulation and rhizosphere carboxylates for three Ptilotus species, and carboxylate adsorption and associated P release. Methods: Ptilotus spp. macrocephalus, nobilis and polystachyus were grown in two soils at 40, 100 and 400 mg P kg-1 soil as KH2PO4. After 6 weeks, dry weight (DW), tissue nutrients and rhizosphere carboxylates were determined. Citrate, malate and oxalate adsorption, and associated P release, was investigated in three soils. Results: For all species, shoot DW and carboxylate amount were little affected by increasing P, while green leaves reached ~ 45–60 mg P g-1 DW: tissue P and carbon were negatively correlated. Oxalate was the dominant carboxylate and a large effect of soil type differed with unit (µmol g-1 root DW or rhizosphere soil DW, µmol plant-1). Adsorption was highest for oxalate, but differed with soil type; Freundlich and Langmuir functions generally fitted well. Citrate was the most effective for P release, followed by oxalate. Conclusions: Inability to down-regulate P uptake and rhizosphere carboxylates with increasing P may be characteristic of Ptilotus. The role of these traits in adaptation to P-poor soils merits further investigation.
AB - © 2015, Springer International Publishing Switzerland. Background and aims: Ptilotus polystachyus occurs in phosphorus (P) – poor soils, but can hyperaccumulate P without toxicity. We examined, in P-poor soils, P accumulation and rhizosphere carboxylates for three Ptilotus species, and carboxylate adsorption and associated P release. Methods: Ptilotus spp. macrocephalus, nobilis and polystachyus were grown in two soils at 40, 100 and 400 mg P kg-1 soil as KH2PO4. After 6 weeks, dry weight (DW), tissue nutrients and rhizosphere carboxylates were determined. Citrate, malate and oxalate adsorption, and associated P release, was investigated in three soils. Results: For all species, shoot DW and carboxylate amount were little affected by increasing P, while green leaves reached ~ 45–60 mg P g-1 DW: tissue P and carbon were negatively correlated. Oxalate was the dominant carboxylate and a large effect of soil type differed with unit (µmol g-1 root DW or rhizosphere soil DW, µmol plant-1). Adsorption was highest for oxalate, but differed with soil type; Freundlich and Langmuir functions generally fitted well. Citrate was the most effective for P release, followed by oxalate. Conclusions: Inability to down-regulate P uptake and rhizosphere carboxylates with increasing P may be characteristic of Ptilotus. The role of these traits in adaptation to P-poor soils merits further investigation.
U2 - 10.1007/s11104-015-2784-y
DO - 10.1007/s11104-015-2784-y
M3 - Article
SN - 0032-079X
VL - 402
SP - 145
EP - 158
JO - Plant and Soil
JF - Plant and Soil
IS - 1-2
ER -