Productivity and quality of soybean seeds as a function of potassium application

Cultural practices affect the production and physiological quality of soybean seeds, however the Cerrado these studies are still scarce. Therefore, this study aimed to evaluate the production and physiological quality of soybean seeds (cv. Monsoy 9350) in Piauí Cerrado under the influence of times and doses of potassium. We used a randomized block design in a factorial design, the treatments consisted of the combination of five doses of potassium (30 60, 90, 120 and 150 kg K2O ha-1) + aditional treatment (zero kg ha-1) applied four times: I. 100% at planting, 50 % at planting and 50% at 30 days after sowing (DAS); II. 100% at 30 DAS; III. 50% at 20 DAS and IV. 50% at 40 DAS, with four replications. The yield and harvest index of grain, thousand seed weight, seedling length, seedling dry weight, rate of germination, germination and first count. Regardless of the applied dose, there was no effect of application times on the parameters evaluated. Except for the germination and germination speed index, all other parameters were significantly influenced by K rates. The length and seedling dry weight increased with the increasing use of K, showing greater seed vigor. Doses of 80 to 95 kg ha-1 K2O provide the best results for all parameters evaluated