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

The rate of dormancy loss in barley (Hordeum Vulgare L.) was quantifie d and expressed as a function of storage temperature. The germinabilit y curves followed a positive cumulative normal distribution over stora ge time which allowed the application of probit analysis techniques to the data. Increasing temperature over the range 8 degrees C to 38 deg rees C increased the rate of dormancy loss in a similar manner for fou r separate seed lots of the variety Triumph, from two different season s, regardless of the initial level of germinability. The germinability curve is characterised by the standard deviation of the dormancy peri od, which was determined for each seed lot at each storage temperature . The logarithm of this parameter is a decreasing linear function of s torage temperature over the range of the experiments. A constant stora ge moisture content of 12%, wet basis, was used in all experiments. Ge rmination count was based on appearance of the radicle and changes in germinability with storage time were examined using the results of ger mination counts after three and seven days. Germinability recovery cur ves based on counts after both lest periods can be predicted by a cumu lative normal distribution curve with the same standard deviation, pro viding the estimate of initial germinability is taken from the respect ive test period. The effect of deterioration in a seed lot while it is recovering from dormancy is modelled using a combination of the dorma ncy equation and existing models for prediction of viability loss in b arley.