ISHS Acta Horticulturae 698: VI International Symposium on Chemical and non-Chemical Soil and Substrate Disinfestation - SD2004
IMPLICATIONS OF THE INCREASED GROWTH RESPONSE AFTER FUMIGATION ON FUTURE CROP PROTECTION AND CROP PRODUCTION STRATEGIES |
| Authors: | I.J. Porter, R.W. Brett, S.W. Mattner, H.E. Donohoe |
| Keywords: | methyl bromide, soil disinfestation, rhizosphere, Montreal Protocol, ozone layer, nitrogen, population densities |
| Abstract:
Fumigation of soils is often followed by an increased growth response (IGR), which can increase yields substantially, even for crops grown in soils not necessarily containing any significant plant pathogens. Understanding this response is important because it will assist development and greater adoption of chemical and non chemical alternatives to replace the ozone depleting fumigant, methyl bromide. Results from a range of studies with strawberry and ornamental plants in soils without significant pathogens, showed that the increased growth response after fumigation with methyl bromide, is associated with major alterations in biological and nutrient status of the soils. In particular, large increases in ammonium nitrogen, (up to 500%) together with large reductions in population densities of fungi (up to 99.96%) and flushes in gram negative bacteria are often observed after soil fumigation. IGR was apparent in strawberries, ornamentals (e.g. calendula) and flower bulb trials and this partially contributes to the 30% increase that has been observed after fumigation in trials throughout Australia. Results also show that reductions in microbial population densities of fungi and bacterial pathogens in the rhizosphere of strawberry roots are strongly correlated with increased root growth of strawberries. These results have implications for maximising yields in future production systems. | |
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