Crop Updates 2000 Cereals - part 4

This session covers twelve papers from different authors: BREEDING 1.Response to subsoil acidity of wheat genotypes differing in Al-tolerance, C. Tang, Z. Rengel, E. Diatloff and B. McGann, Soil Science and Plant Nutrition/CLIMA, University of Western Australia 2. Application of molecular markers in Barley Improvement, Mehmet Cakir1, Nick Galwey1 and David Poulsen2, 1Plant Sciences, Faculty of Agriculture, University of Western Australia, 2Queensland Department of Primary Industries, Hermitage Research Station, Queensland 3. Implementation of molecular markers for wheat improvement in the Western Region, M. Carter1, A. Briney1, R. Wilson2, R.H. Potter1 and M.G.K. Jones1, 1Western Australian State Agricultural Biotechnology Centre, Murdoch University, 2Crop Industries, Agriculture Western Australia 4. Performance in 1999 of recently released wheat varieties in Western Australia, Robin Wilson, Iain Barclay, Robyn McLean, Dean Diepeveen and Robert Loughman, Agriculture Western Australia ECONOMICS 5. Outlook for prices and implications for rotations, Ross Kingwell1 2, Michael O’Connell1, Simone Blennerhasset1 1Agriculture Western Australia, 2University of Western Australia 6. Price Risk Management and the Western Australian Grain Producer, Benjamin Michael Tiller, Muresk Institute of Agriculture FORECASTING 7. Can we forecast wheat yields in Western Australia, Senthold Asseng1, Holger Meinke2, and Bill Bowden3, 1CSIRO Plant Industry, 2 APSRU/DPI, 3Agriculture Western Australia ON FARM TESTING 8. On-farm testing, the quiet revolution continues, Jeff Russell1, Ivan Lee2 1Agriculture Western Australia, 2 Farmer Kunjin TopCrop group, Corrigin GRAIN STORAGE 9. CD-ROM tool for growers and advisers: Managing on-farm grain storage – effective practices for the delivery of quality assured products, Clare Johnson1, Chris Newman2 1Quality Wheat CRC Ltd, 2Production Resource Protection Services, Agriculture Western Australia 10. The Internet as a tool for managing grain insects, Robert Emery, Romolo Tassone and Ernestos Kostas, Agriculture Western Australia SUMMER CROPS AND WINDBREAK EFFECT ON YIELD 11. Summer crop Update and agronomic considerations, Graeme Ralph, Pioneer Hi-Bred Australia Pty Ltd 12. The effect of tree windbreaks on grain yield in the medium and low rainfall areas in Western Australia, Robert Sudmeyer, David Hall and Harvey Jones, Agriculture Western Australi

AtHKT1;1 Mediates Nernstian Sodium Channel Transport Properties in Arabidopsis Root Stelar Cells

The Arabidopsis AtHKT1;1 protein was identified as a sodium (Na+) transporter by heterologous expression in Xenopus laevis oocytes and Saccharomyces cerevisiae. However, direct comparative in vivo electrophysiological analyses of a plant HKT transporter in wild-type and hkt loss-of-function mutants has not yet been reported and it has been recently argued that heterologous expression systems may alter properties of plant transporters, including HKT transporters. In this report, we analyze several key functions of AtHKT1;1-mediated ion currents in their native root stelar cells, including Na+ and K+ conductances, AtHKT1;1-mediated outward currents, and shifts in reversal potentials in the presence of defined intracellular and extracellular salt concentrations. Enhancer trap Arabidopsis plants with GFP-labeled root stelar cells were used to investigate AtHKT1;1-dependent ion transport properties using patch clamp electrophysiology in wild-type and athkt1;1 mutant plants. AtHKT1;1-dependent currents were carried by sodium ions and these currents were not observed in athkt1;1 mutant stelar cells. However, K+ currents in wild-type and athkt1;1 root stelar cell protoplasts were indistinguishable correlating with the Na+ over K+ selectivity of AtHKT1;1-mediated transport. Moreover, AtHKT1;1-mediated currents did not show a strong voltage dependence in vivo. Unexpectedly, removal of extracellular Na+ caused a reduction in AtHKT1;1-mediated outward currents in Columbia root stelar cells and Xenopus oocytes, indicating a role for external Na+ in regulation of AtHKT1;1 activity. Shifting the NaCl gradient in root stelar cells showed a Nernstian shift in the reversal potential providing biophysical evidence for the model that AtHKT1;1 mediates passive Na+ channel transport properties

Use of GEOCHEM-PC to predict rare earth element (REE) species in nutrient solutions

The interpretation of results of some experiments examining effects of rare earth elements (REE) on plant growth may have been complicated by rare earth phosphate precipitation. Simulations were undertaken using the computer model GEOCHEM-PC to define REE solubility limits and predict REE species in low and high ionic strength nutrient solutions. In low ionic strength solutions containing 5 μM P, lanthanum phosphate (LaPO) precipitation is predicted to occur at solution pH>4.0, reaching a maximum (>95% of total) at pH 5.5. In high ionic strength solutions (1000 μM P) over 95% of the La is predicted to precipitate as phosphate at pH>4.0. The predicted behaviour of cerium (Ce) was closely similar to that for La. At pH 5.5, the concentration of REE species in solution can be increased only after virtually all the P has been precipitated. Consequently, it is important to consider REE-P interactions in nutrient solutions when investigating REE effects on plant growth

Concentrations of rare earth elements in some Australian soils

Total, exchangeable, and soil solution concentrations were measured for 15 rare earth elements (REEs) in 9 soils from Queensland and New South Wales. In a further 10 acid soils, effects of amendment with CaCO or CaSO·2HO were measured on the concentrations of REEs in soil solution. The total concentration of the REEs in soil solutions from unamended soils ranged from below the detection limit (0.007 μM) to 0.64 μM. Lanthanum (La) and cerium (Ce) were the REEs present in the greatest concentrations, the highest concentrations measured in the diverse suite of soils being 0.13 μM La and 0.51 μM Ce. Rare earth elements with higher atomic numbers were present in very low concentrations. Exchangeable REEs accounted for 0.07 to 12.6% of the total REEs measured in the soils. Addition of CaCO increased soil solution pH and decreased REE concentrations in soil solution, whilst CaSO·2HO decreased soil solution pH and increased the concentrations of REEs in soil solution. Solubility calculations suggest that CePO may be the phase controlling the concentration of Ce in soil solution