ABSTRACT. The objectives of this study were to evaluate the effect of the chemical composition of soybean seeds and the efficiency of seed mineral supplementation on physiological quality and field performance. Two seed lots (high and low levels of mineral nutrition), with or without supplemental macro- and micronutrients, of three soybean cultivars (BMX Potência RR, BMX Turbo RR, and BMX Magna RR) were used. For the laboratory experiment, a completely randomized design with four replications was used. To evaluate the physiological quality of the seeds, the water content, first count, germination, 1,000-seed weight, and length and dry weight of the seedling were determined. For the field experiment, a randomized block design with four replications was used, and seedling emergence and grain yield were evaluated. Seeds with higher nutrient content produced seedlings of greater vigor and higher grain yield for all of the cultivars studied. The use of mineral supplementation in seed lots with low nutrient content resulted in greater vigor under laboratory conditions. The increase in grain yield after mineral supplementation depends on the quality of the seed lot.

ABSTRACT. Inoculation with nitrogen-fixing bacteria (Bradyrhizobium) is an indispensable technology to increase the productivity of the soybean crop. The objective of this study was to evaluate the viability of the inoculation with Bradyrizobium bacteria associated with the osmoprotector coating on different pre-sowing days and the effect of different soil pH on the components of yield, nodulation and grain yield of soybean. Two soybean cultivars were used, sown in two seasons and submitted to soil pH of 5.3 and 6.5. The seeds were inoculated at different pre-sowin periods with Bradyrizobium bacteria in the presence or absence of osmoprotectants. In the cultivar NA 5909RG (pH 5.3), the seeds inoculated with Bradyrhizobium and osmoprotector, at four and seven days of pre-sowing, presented an increase of 10.8% and 8.3% of productivity, in relation to those without osmoprotector. The osmoprotector and the inoculation of Bradyrhizobium increases the number and dry mass of nodules in soil with more acidic pH. The soil of lower acidity is responsible for higher grain yield, compared to the higher acidity, when both were not inoculated. The variable with the greatest explanatory power and contribution in the variability in the data of the experiment is the grain yield.