THERMAL AND CHEMICAL TREATMENTS ON WHEAT SEEDS

This work was conducted to study the effectiveness of different treatments, thermal and chemical, for breaking dormancy of seeds of wheat (Triticum aestivum L). Four seed lots of the Roots variety were used. The treatments were T1- pre-cool: 50-10 degrees C for a period of five days; T2- pre-drying: 30-35 degrees C for a period of seven days in an oven with air circulation; T3- pre-drying: 50 degrees C in an oven with air circulation for 72h; T4- pre-drying: 50 degrees C in an oven with circulating air for 96h, T5- gibberellic acid (GA(3)): wet the substrate with a 0.02% solution (200mg GA(3)/liter); and T6- potassium nitrate (KNO): dampen the substrate with a 2% solution (200mg KNO3/liter); and T7- control: untreated seeds. The imbibition curve and tetrazolium test were also carried out to assess the time of radicle protrusion and seed viability, respectively. The trial was randomized and analysis of variance was conducted in a factorial 4x7 scheme (seed lots x treatments to overcome dormancy), with five replicates per treatment. The thermal method, using temperatures of 30-35 and 50 degrees C (72h) was more efficient in overcoming dormancy of wheat seeds.