THE QUANTIFICATION OF DORMANCY LOSS IN BARLEY (HORDEUM-VULGARE L)

The rate of dormancy loss in barley (Hordeum Vulgare L.) was quantified and expressed as a function of storage temperature. The germinability curves followed a positive cumulative normal distribution over storage time which allowed the application of probit analysis techniques to the data. Increasing temperature over the range 8 degrees C to 38 degrees C increased the rate of dormancy loss in a similar manner for four separate seed lots of the variety Triumph, from two different seasons, regardless of the initial level of germinability. The germinability curve is characterised by the standard deviation of the dormancy period, which was determined for each seed lot at each storage temperature. The logarithm of this parameter is a decreasing linear function of storage temperature over the range of the experiments. A constant storage moisture content of 12%, wet basis, was used in all experiments. Germination count was based on appearance of the radicle and changes in germinability with storage time were examined using the results of germination counts after three and seven days. Germinability recovery curves based on counts after both lest periods can be predicted by a cumulative normal distribution curve with the same standard deviation, providing the estimate of initial germinability is taken from the respective test period. The effect of deterioration in a seed lot while it is recovering from dormancy is modelled using a combination of the dormancy equation and existing models for prediction of viability loss in barley.