To evaluate the effectiveness of gibberellic acid (GA3) in breaking rice seed dormancy
and the use of a-amylase enzyme activity as an indicator of the dormancy level, seed from the
intensively dormant irrigated cultivar Urucuia were used. The seeds were submitted to a predrying
process in a forced air circulation chamber under 40ºC during 7 days and submersed in 30
mL of GA3 solution under 0, 10, 30 and 60 mg/L H2O concentrations, during 2, 24 and 36 hours.
After the treatments, the a-amylase activity was determined by using the polyacrilamide
electrophoresis and spectrophotometry. At the same time, the germination test was made. The
results indicated a gain in germination and in a-amylase activity in higher concentrations and
soaking time of seeds in GA3. These observations support the conclusion that soaking seed in 60
mg GA3/L during 36 hours can be used as a quick and efficient treatment in breaking rice seed
dormancy and is equivalent to the forced air circulation chamber at 40ºC during 7 days. The aamylase
enzyme activity proved to be as an efficient marker of the seeds dormancy level.