An inexpensive and mechanically simple technique has been developed to maintain realistically low P concentrations in nutrient solutions using a solid-phase buffer. Phosphate is adsorbed on alumina in a PVC column, and the resulting alumina-P is desorbed against nutrient solution circulated through the column. Kinetics of P adsorption and desorption indicate that the solid-phase-P has rapidly and slowly desorbing components and that buffering capacity is limited by desorption from the solid phase. The technique has been used to maintain P concentrations as low as 0.4 mmolm -3for 26 days in experiments with maize (Zea mays L.), and in solution cultures with prune (Prunus domestics L.) trees. Effects of P supply on P accumulation and P transport are discussed.
Bibliographical noteFunding Information:
We thank Dr. D.N. Munns for helpful discussions, Dr. J. Hohenberg for preliminary data on P adsorption by alumina, and Mr. J. Bold for X-ray spectographic data. Funds were provided by a grant from Allied Chemical Company to A.L. and from the California Prune Board to R.C. A preliminary account of part of this work has been presented elsewhere (Elliott and Lauchli, 1982).
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- Solution culture