Evolução da deterioração por umidade e danos mecânicos durante o armazenamento de semente de soja

Abstract

In some of the Northern regions of the Paraná state, the physiological quality of soybean seeds of short-season cultivars can be low or irregular due the poor weather conditions. Usually in this period the weather is rainy and presents high humidity which is normally associated with high temperatures. These stressful conditions coincide with the phase of seed maturation and as a result, high levels of weathering damage are developed in the seeds, decreasing germination and vigor. Several seed lots with quality within the standards for commercialization present a sharp decrease in germination and vigor during storage, however so far the exact cause of this quality loss has not been fully explained. This study was carried out with the objective of determining the possible evolution of weathering damage on soybean seeds during storage and to verify if this evolution may be associated with seed quality reductions during this period. Seed quality evaluations were performed for studying weathering damage as determined by the tetrazolium test in seeds of three short-season soybean cultivars with two vigor levels. These seeds were produced in Faxinal and stored in Mandaguari, regions located in Northern of Paraná State. Seed quality evaluations were performed during six periods with a 45-day interval, and consisted of the following tests: germination; accelerated aging; and tetrazolium. The parameters determined by the tetrazolium test that were considered in this study were viability [TZ (1-5)], vigor [TZ (1-3)], weathering damage [TZ (level 3)] and mechanical damage [TZ (6-8)]. Based on the results it was concluded that weathering damage is the type of damage that increases the most during storage of soybean seeds, resulting in significant losses of germination during this period.