SUMMARY Drosera whittakeri was grown in sand cultures supplemented with inorganic salt solutions lacking either nitrogen, sulphur, phosphorus or the microelements. Application of the insect Drosophila melanogaster to the tentacles of plants raised on nitrogen or sulphur deficient medium, enhanced growth, which on nitrogen deficient medium was accompanied by decreased nitrogen content per unit weight although the total nitrogen per plant was unaffected. Application of insects to plants on media deficient in phosphorus or the microelements had no effect on growth but significantly increased the phosphorus content of plants grown on a complete nutrient solution or media deficient in phosphorus or nitrogen. Insects would not serve as a heterotrophic carbon source for the realization of maximum growth of plants grown at very low light intensities. Optimum growth of Drosera binata (and usually D. whittakeri) was attained by applying insects to plants raised on nitrogen‐free medium; addition of inorganic nitrogen (as nitrate) to the nutrient solution to plants raised under these conditions inhibited growth. Optimum growth was not achieved by growing plants on a complete nutrient solution in the absence of insects. Up to 50% of the phosphorus in the tubers of D. whittakeri occurred as inositol hexaphos‐phate. Phosphorus was rapidly transferred to the growing parts of the plant on emergence. During the growing season, plants with higher than average phosphorus content developed new rhizomes on which new tubers formed. The indigenous distribution of Drosera species in southeastern Australia is not restricted to soils of very low phosphorus, nitrogen and sulphur status.

SUMMARY The occurrence of glutamine synthetase isoforms in algae, from seven different phyla, has been investigated, using ion‐exchange chromatography. The algae have been classified into three groups according to their glutamine synthetase isoform content. The first group is characterized by having only the cytosolic glutamine synthetase, whereas the second group is distinguished by having only the chloroplastic glutamine synthetase. The third group is characterized by having both the isoenzymes. Stability studies were used along with the elution profiles from ion‐exchange chromatography to designate the isoforms to the cytosolic or the chloroplastic isoform. Immunoprecipitation studies, for specific identification of the cytosolic and chloroplastic isoforms showed varied results and indicated that the two forms from the lower algae have very similar antigenic sites.

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SUMMARYMeasurements in two sub-tropical rainforests demonstrated that (i) in one rainforest succession, total soil phenols varied dramatically throughout the study year with soils from the 'climax' rainforest exhibiting highest phenol levels, the nature of these phenolic compounds was not investigated; (ii) in the other rainforest succession, the 55-year-oid regrowth exhibited highest total phenols, but the level of condensed tannins increased throughout the succession. The highest level of nitrification was observed in soils containing highest total phenols but the addition of ferulic acid decreased nitrification.Studies on Argyrodendron trifoliolatum demonstrated that addition of the phenol, caffeic acid, to nutrient media enhanced leaf concentrations of Zn, Mn and P. Increasing light intensities, however, decreased foliar concentrations of Fe, Zn, Mn and P but had no effect on Ca or N. Plants raised on ammonium -N exhibited higher levels of Fe, Zn, Mn and P than those raised on nitrate-N.Glasshouse trials showed that at low light intensities omission of N, P and N + P did not dramatically enhance leaf phenol production. Almost invariably, an increase in light intensity increased leaf phenols but only one of the four species examined (Syzygium fioribundum) exhibited marked responses to nutrient deficiencies at high light intensities, with the omission of nitrogen leading to highest leaf phenols.

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