The characteristics of materials used in packages for seed storage may have a negative influence in the deterioration process, causing future problems during the period of storage and in emergence in the field. In this study, the objective was to evaluate the physiological quality of soybean seeds, stored in different packages with and without the addition of CO₂ (modified atmosphere), for different periods of storage and in uncontrolled environmental conditions. In order to carry out the experiment, a completely randomized design was used in a split-plot scheme, with three types of packages (permeable, hermetic package inside the permeable package and hermetic package inside the permeable package with CO₂ injection) in the main plot and six storage periods (zero, 45, 90, 135, 180 and 225 days) in the subplot, with four repetitions, totaling 72 experimental units. In hermetic packages multi-layer paper was used with or without CO₂ injection, stored them for 225 days and performed an assessment at regular intervals of 45 days. At each period, the seeds were submitted to tests for moisture content, germination, seedling emergence, accelerated aging and electrical conductivity. The hermetic package, with and without CO₂ injection, decreases the speed of deterioration of soybean seeds. The hermetic package allows a higher physiological quality of soybeans compared to the permeable package, with a storage period of up to 180 days under uncontrolled environmental conditions. The addition of CO₂ inside the hermetic packages favors the maintenance of the physiological quality of soybean seeds in storage.

Soybean is one of the leading commodities in Brazilian agribusiness. Its cultivation is widespread in different seed-producing regions of the country, where it generates income and local development. In this context, the soybean seed is a fundamental input, as its quality strongly influences the success of the crop. However, the period after the achievement of physiological maturity is critical for the maintenance of seed quality. For that reason, this study aimed at evaluating the effect of harvest delay on both the initial and final qualities of soybean seeds. The research consisted of four harvest times, in which the initial quality was assessed through tests of first germination count, germination, accelerated aging and tetrazolium. After 120 days of storage, the germination and accelerated aging tests were once again conducted. The experiment complied with a completely randomized block design with eight replications. The rainfall was monitored during the pre-harvest phase. All variables experienced negative impacts due to the delay in harvesting. Also, the seeds suffered more damage as the delay progressed, and the variables germination and seed vigor decreased after the storage period.