TY - JOUR
T1 - Growth, carboxylate exudates and nutrient dynamics in three herbaceous perennial plant species under low, moderate and high phosphorus supply
AU - Suriyagoda, Lalith
AU - Lambers, Hans
AU - Renton, Michael
AU - Ryan, Megan
PY - 2012/9/1
Y1 - 2012/9/1
N2 - Background and aimsAustralian herbaceous native species have evolved in phosphorus (P) impoverished soils. Our objective was to explore shoot and root adaptations of two of these species with potential to be developed as pasture plants, at low, moderate and high P supply after 4 and 7 weeks of growth.MethodsA glasshouse experiment examined the effect of 5, 20 and 80 mg P kg−1 air-dry soil on growth, rhizosphere carboxylate content, and mineral nutrition of two Australian native perennials, Kennedia nigricans (Fabaceae) and Ptilotus polystachyus (Amaranthaceae), and the exotic Medicago sativa (Fabaceae).Key resultsLeaf P concentrations at P80 were 6, 14 and 52 mg P g−1 leaf dry weight for M. sativa, K. nigricans and P. polystachyus, respectively. As soil P concentration increased, rhizosphere carboxylate content decreased for M. sativa, increased and then decreased for K. nigricans and was unchanged for P. polystachyus. For all species, the contribution of malic acid declined at the second harvest. For all species and P treatments, the amount of rhizosphere carboxylates per unit root length decreased as root length of a plant increased. Plant P content was determined more by P uptake rate per unit root length and time than by root length. Uptake of Mo for all species, and uptake of K, Mg and Mn for P. polystachyus, increased with soil P concentration. Uptake of Fe and S was higher when the content of carboxylates in the rhizosphere was higher.ConclusionRoot physiological adaptations (i.e. rhizosphere carboxylate content and P-uptake rate) are more important than morphological adaptations (i.e. root length and diameter) to enhance the uptake of P and cations.
AB - Background and aimsAustralian herbaceous native species have evolved in phosphorus (P) impoverished soils. Our objective was to explore shoot and root adaptations of two of these species with potential to be developed as pasture plants, at low, moderate and high P supply after 4 and 7 weeks of growth.MethodsA glasshouse experiment examined the effect of 5, 20 and 80 mg P kg−1 air-dry soil on growth, rhizosphere carboxylate content, and mineral nutrition of two Australian native perennials, Kennedia nigricans (Fabaceae) and Ptilotus polystachyus (Amaranthaceae), and the exotic Medicago sativa (Fabaceae).Key resultsLeaf P concentrations at P80 were 6, 14 and 52 mg P g−1 leaf dry weight for M. sativa, K. nigricans and P. polystachyus, respectively. As soil P concentration increased, rhizosphere carboxylate content decreased for M. sativa, increased and then decreased for K. nigricans and was unchanged for P. polystachyus. For all species, the contribution of malic acid declined at the second harvest. For all species and P treatments, the amount of rhizosphere carboxylates per unit root length decreased as root length of a plant increased. Plant P content was determined more by P uptake rate per unit root length and time than by root length. Uptake of Mo for all species, and uptake of K, Mg and Mn for P. polystachyus, increased with soil P concentration. Uptake of Fe and S was higher when the content of carboxylates in the rhizosphere was higher.ConclusionRoot physiological adaptations (i.e. rhizosphere carboxylate content and P-uptake rate) are more important than morphological adaptations (i.e. root length and diameter) to enhance the uptake of P and cations.
U2 - 10.1007/s11104-012-1311-7
DO - 10.1007/s11104-012-1311-7
M3 - Article
SN - 0032-079X
VL - 358
SP - 105
EP - 117
JO - Plant and Soil
JF - Plant and Soil
IS - 1-2
ER -