Mechanical damage and physiological quality of soybean seeds during conditioning: size matters?

Resumen

Seed conditioning is a fundamental component in the production of high quality seeds, but the possibility of mechanical damage in its stages can compromise the final result of the process. The aim of this study was to evaluate the relationship between soybean seed size and the efficiency of seed conditioning in removing damaged seeds from lots, as well as the effects of these factors on physiological quality throughout distinct stages of the process. Seeds from two cultivars (M6410 IPRO and FLX IPRO) were sampled at the seed conditioning plant. The experiment was conducted using a 5 × 2 factorial arrangement, which included five sampling points during conditioning and two classifications of seeds based on size (5.5 and 6.5 mm). The cultivars were analyzed separately. The following parameters were evaluated: apparent specific mass, mechanical damage (using the sodium hypochlorite test), tetrazolium test (mechanical damage, weathering deterioration and vigor), germination and accelerated aging. Under seed conditioning, larger soybean seeds exhibited higher mechanical damage and lower physiological quality, while seeds with greater apparent specific mass demonstrated better physiological quality. A 3% difference in specific mass between the upper and lower sections of a gravity separator effectively stratified seeds by quality. The gravity separator efficiently separated seeds with mechanical damage and differences in vigor and germination. However, weathering-related deterioration was independent of seed size, and seeds with weathering deterioration were not effectively removed by the gravity separator.