Record ID No. |
3724 |
Author(s) |
He, H., Bleby, T.M., Veneklaas, E.J., Lambers, H. , 2012 |
Affiliation |
School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia, Email: heh01@student.uwa.edu.au |
Title |
Arid-zone Acacia species can access poorly soluble iron phosphate but show limited growth response |
Source. Vol.(no):Page |
Plant and Soil, 358 (1-2):119-130p. |
Categories |
Mycorrhiza General |
Subjects |
Soil plant relations |
Sub-subjects |
Fungal evaluation |
Host |
A.cacia stipuligera and A. ancistrocarpa, A. stellaticeps, A. robeorum |
Organism |
Mycorrhizal Fungi |
Country |
Australia |
Abstracts |
Background and aims: Phosphorus (P) is a commonly limiting nutrient for plant growth in natural environments. Many legumes capable of N2-fixation require more P than non-legumes do. Some legume crops can use sparingly soluble forms of P such as iron phosphate much better than other species, but reports on the ability of woody legumes to access iron phosphate are rare. Methods: Plants of four Acacia species (Acacia stipuligera F. Muell., A. ancistrocarpa Maiden & Blakely, A. stellaticeps Kodela, Tindale & D. Keith and A. robeorum Maslin), native to the Great Sandy Desert in north-western Australia, were grown in a glasshouse in river sand with different levels of iron phosphate, between 0 and 16 μg P g-1 sand. Plant growth, tissue P concentrations, and pH and carboxylates in the rhizosphere were measured. Results: Growth of A. stipuligera and A. ancistrocarpa was not responsive to increased P supply; in contrast, A. stellaticeps and A. robeorum produced significantly more root and shoot dry mass at 8 and 16 μg P g-1 sand than at 0 μg P g-1 sand; differences in root mass ratio were significant between species but not between P treatments. A. robeorum was the only species colonised by mycorrhizal fungi, and the colonisation percentage decreased with increasing P supply. In all species, P-uptake rates and tissue P concentrations were significantly higher at greater P supply. Rhizosphere pH and the amount of carboxylates in the rhizosphere decreased with increasing P supply. Conclusions: Net P uptake increased with increasing P supply, showing that the present Acacia species can access P from iron phosphate. However, due to their inherently slow growth rate, enhanced P supply did not increase growth of two of the four studied species. The ability of the Acacia species to access P from iron phosphate is presumably related with carboxylate exudation and rhizosphere acidification. |