© 1986 Heron Publishing—Victoria, Canada
Effects of anaerobic growth conditions on phosphorus tissue concentrations and absorption rates of southern pine seedlings
M. A. Topa (1) and K. W. McLeod (2)
1. Department of Plant Biology, 505 S. Goodwin Ave., University of Illinois, Urbana, Illinois 61801, USA / 2. Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29801, USA /
Summary
A non-circulating, continuously flowing solution culture was used to examine the long- and short-term effects of anaerobic
growth conditions on phosphorus uptake in 12-week-old seedlings of three pine species. Sand pine (Pinus clausa (Engelm.) Sarg.) and a drought-hardy loblolly pine (P. taeda L.) had the largest reductions in biomass after 8 weeks in anaerobic solution, whereas the more flood-tolerant pond pine
(P. serotina Michx.) and wet-site loblolly pine seedlings were least affected.
Anaerobic growth conditions reduced P concentrations in the shoot and increased P concentrations in the root. Short-term 32P-uptake experiments were conducted with intact seedlings to determine absorption rates (influx) of inorganic phosphate (Pi)
by aerobically and anaerobically grown pine seedlings. Influx of Pi was weakly correlated with shoot fresh weight, root fresh
weight, root P and shoot P per gram fresh weight root, suggesting that internal P levels and biomass influenced Pi absorption.
The highest Pi absorption rates were found in anaerobically grown seedlings under anaerobic 32P-uptake conditions. Of these, sand pine had the highest absorption rate in 50 μM KH2PO4 (0.96 μmol Pi g–1 FW root h–1), and the wet-site loblolly pine exhibited the lowest rate (0.24 μmol Pi g–1 FW root h–1). Aerobically grown seedlings had similar Pi absorption rates that were not significantly affected by O2 concentration in the 32P-uptake solution.
