Leaf phosphorus allocation and photosynthesis in native Australian plants differs between soil parent material types

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Abstract
Background and aims: There is considerable interest in how plants allocate phosphorus (P) and how this varies by environment. How leaf P fractions change with soil P supplies and soil type is essential to understand the roles of P in storage, structure and biochemistry including photosynthesis. Here, we contrasted the P allocation patterns for native woody plants in south-eastern Australia on soils derived from either P-poor sedimentary or P-rich igneous parent materials. Methods: We measured total leaf P and four leaf P fractions: inorganic phosphate (P i ), metabolite P, nucleic acid P, and lipid P for 33 native species. We also measured photosynthetic capacity ( A sat ) for species across four sites with contrasting soil P and parent material types: high total soil P from basalt versus low total soil P in sands. Results: The leaf P i fraction scaled consistently with total leaf P within and across the high-P versus low-P sites. Species growing on high P soils from basalt tended to have similar P fractions of total P to those of species on low P soils, except for the lipid P fraction which was greater for species at high P sites. There was a substantial reduction in P allocated to the lipid fraction for species on low P soils, especially in Proteaceae species. Leaf photosynthetic P-use efficiency was significantly higher with lower leaf P concentration. Conclusion: The adaptive strategy of reducing phospholipids in leaves occurs in multiple species in low-P environments, including non-Proteaceae. This resulted in species from more than one plant family maintaining lower leaf P concentrations on sedimentary-derived soils than on igneous soils, thus achieving more efficient P use in photosynthesis at low P.
Funding Information
  • Australian Research Council (DP210100115)
  • Western Sydney University

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