IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...

Recommendations

Info

17 th International Congress on Nitrogen Fixation Fremantle, Western Australia 27 November – 1 December 2011 Session Details: Tuesday 29 November 2011 Concurrent Session 6 – Field Applications II 1100 - 1230 Authors: Ryan Farquharson 1 , Ross Ballard 2 , Nigel Charman 2 , Jeff Baldock 1 1 CSIRO Land and Water. PMB 2 Glen Osmond, South Australia 5064. 2 South Australian Research and Development Institute. GPO Box 397, Adelaide, South Australia 5001. Presentation Title: Symbiotic performance of a herbicide tolerant Medicago littoralis Presentation Time: 1200 – 1220 Group B herbicides inhibit the acetohydroxyacid synthase (AHAS – also known as acetolactate synthase) enzyme in the pathway of branched chain amino acid synthesis. These herbicides have gained widespread use worldwide; however the potential impacts on nitrogen fixation are underappreciated. A new strand medic (Medicago littoralis) cultivar (FEH-1) was developed by chemical mutagenesis of seed of the Herald variety (Heap, 2000). FEH-1 displayed tolerance to various group B herbicides including the sulfonylurea class, however this work had only analysed biomass production and yield with no consideration of nitrogen fixation (Heap, 2000; Howie and Bell, 2005). Through a targeted approach, a single mutation in the AHAS gene was identified as the mechanism of herbicide tolerance (Oldach et al., 2008). An experiment comparing the symbiotic performance of FEH-1 and Herald showed that FEH-1 had useful tolerance to chlorsulfuron, with higher biomass production, nodulation and nitrogen fixation than Herald after application of that herbicide. However it was noted that in the absence of herbicide, Herald had greater biomass production, nodulation and nitrogen fixation than FEH-1. Differences in seed mass and nitrogen could not explain the disparity and a „tolerance penalty‟ was proposed. A subsequent experiment measuring the growth of Herald and FEH-1 with different strains of rhizobia showed symbiotic compatibility had changed in FEH-1. This may be contributing to the tolerance penalty observed when FEH-1 is grown in the absence of herbicide. Although there is scope to better understand the complexities surrounding group B herbicides and nitrogen fixation, it is clear that where in-crop or residual herbicides are of concern, herbicide tolerant varieties will provide a useful option to maintain inputs of biologically fixed nitrogen. Heap J (2000). Increasing Medicago resistance to soil residues of ALS-inhibiting herbicides. Thesis, University of Adelaide. Howie J & Bell CA (2005) Field performance of an annual medic tolerant of sulfonylurea herbicide residues. Proceedings of the XX International Grassland Congress, Dublin, Ireland. Oldach KH, Peck DM, Cheong J, Williams KJ, Nair RM (2008) Identification of a chemically induced point mutation mediating herbicide tolerance in annual medics (Medicago spp.) 48 2011
17 th International Congress on Nitrogen Fixation Fremantle, Western Australia 27 November – 1 December 2011 Session Details: Tuesday 29 November 2011 Plenary Session 4 1330 - 1500 Authors Graham W. O‟Hara 1 Ron J. Yates 1, 2 & John G. Howieson 1 1 Centre for Rhizobium Studies, School of Biological Sciences and Biotechnology, Murdoch University, South Street, Murdoch 6150, Australia. 2 Department of Agriculture and Food Western Australia, 3 Baron-Hay Court, South Perth, Western Australia 6151 Presentation Title: Fifteen years of revolution in legume N-fixation in southern Australia Presentation Time: 1330 – 1400 Legumes in southern Australian agriculture have been, and continue to be, introduced from exotic centres of origin. Inoculation is essential because Australian soils do not naturally contain rhizobia that form effective nitrogen-fixing symbioses with these legumes. During the past 15 years the Centre for Rhizobium Studies & the National Rhizobium Program have developed 15 strains of rhizobia for commercial production, and contributed to development of new legumes which, together with their rhizobia, have been sown over 5 million ha. in southern Australia. In addition, new insights have been provided into phenomena affecting symbiotic performance e.g. the role of horizontal gene transfer in development of poorly effective soil populations of rhizobia, and selective nodulation. Selective nodulation describes an active phenomenon that results in the establishment of a symbiosis between a legume and an effective strain of rhizobia in the presence of ineffective strains. Selective nodulation can overcome a numerical disadvantage in the effective microsymbiontt when there is a population size window of between 1,000 and 100,000 cells. Alternative species of herbaceous perennial legumes (e.g. Lebeckia spp., Rynchosia spp.) originating in southern Africa and nodulated by novel Burkholderia spp. are being evaluated for their potential role in providing green feed in autumn and late spring. Target soils do not sustain traditional legumes (e.g. lucerne, white clover, lotus) because of abiotic stresses such as low pH, low clay content, low nutrient status and low rainfall. Overcoming the challenges of establishing symbioses with these new legumes will be discussed. The Grain Research and Development Corporation (GRDC) of Australia support the National Rhizobium Program. 49 2011
Page 1 and 2: PrinciPal SPonSor: SPonSorS: Progra
Page 3 and 4: INVENTING THE FUTURE IN INOCULANTS
Page 5 and 6: 17 ICNF Organising Committee Graham
Page 7 and 8: Cottesloe Beach © Tourism Western
Page 9 and 10: GeNeRAl INfoRmATIoN aTM’s Automat
Page 11 and 12: 16:30 - 16:50 Felix Dakora Tshwane
Page 14 and 15: Thursday 1 December 2011 08:00 - 12
Page 16 and 17: 17 th International Congress on Nit
Page 98 and 99:
17 th International Congress on Nit
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
Page 130 and 131:
Page 132 and 133:
Page 134 and 135:
Page 136 and 137:
Page 138 and 139:
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
Page 148 and 149:
Page 150 and 151:
Page 152 and 153:
Page 154 and 155:
Page 156 and 157:
Page 158 and 159:
Page 160 and 161:
Page 162 and 163:
Page 164 and 165:
Page 166 and 167:
Page 168 and 169:
show all

IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...

Create successful ePaper yourself

Delete template?

Save as template?