Dormancy in Malting Barley: Quantifying the Effect of Storage Temperature on Different Varieties and the Response to Sudden Cooling

The rates of break of dormancy of the varieties Blenheim and Pipkin were examined during storage at temperatures of 8, 18, 26 and 33°C. The results were fitted to an established probit model of dormancy and compared with the previously fitted equations for Triumph. Triumph was shown to be the variety with the slowest recovery rate and this was consistent with the observations of other researchers. A similarity between varieties in the change of recovery rate with temperature suggested a consistency in the controlling reaction. A second experiment examined whether the sudden cooling of warm barley could induce ‘secondary dormancy’. The variety Triumph was stored at 12% moisture content and 33°C. Samples were then transferred to 8 or 15°C at different times. This procedure did not bring about any significant reduction in germinative energy. The only effect of a sudden temperature drop was a reduction in the rate of emergence from dormancy. ‘Secondary dormancy’ was not induced. The work is introduced and the results discussed in the context of the development of a thermally based integrated control strategy for malting barley. The strategy was designed to minimise the use of chemicals.