**3. Material and methods**

Three rice cultivars where used: two conventional (BR IRGA 417, BR IRGA 424) and one hybrid (Avax R.). The cultivars had the same physiological quality and were evaluated for tolerance to low temperature through the germination test. The seeds were treated with a commercial product containing 35 grams of thiamethoxam active ingredient per li‐ ter of product. The treatments were: Treatment 1 - untreated seeds; Treatment 2 - 100ml of product/100kg of seed; Treatment 3 - 200 ml of product/100kg of seed; Treatment 4 - 300 ml of product/100kg of seed and Treatment 5 - 400 ml of product/100kg of seed, pri‐ or to sowing.

The germination test was performed in three replications, eight sub-samples of 50 seeds (400 seeds per replicate) for each cultivar. The seeds were placed to germinate in paper rolls moistened with water equivalent to 2,5 times the weight of the substrate, following the crite‐ ria established by the Rules for Seed Testing (Brazil, 2009). Five germination temperatures were used: 25, 20, 18, 15 and 13°C. The germination test at temperatures of 25 and 20ºC were performed in the germinator, and at temperatures 18, 15 and 13°C held in BOD. The count‐ ing of normal seedlings was performed seven days after sowing for temperatures of 25, 20 and 18°C and at 21 days for temperatures of 15 and 13ºC.
