The effect of plant density of soybean cultivars sowed on spring and autumn seasons,
on seed physiological quality at harvesting time and after storage was studied. The experimental
design was a randomized blocks, four replications. Two sowing times (spring and autumn), were
combined with three plant density (300,000/ha, 400,000/ha and 500,000/ha), and seven soybean
cultivars (IAC-16, IAC-Foscarin 31, FT-2, IAC-100, IAC-8, IAC-9 and FT-Cristalina).
Physiological seed quality (germination and vigor) was determined at harvesting time and six
month after storage under uncontrolled conditions. Autumn sowing provided the best seed quality
that conforms with the seed market standards for Mato Grosso of Sul State. Seed physiological
quality six month after harvesting was lower than at harvesting time. Seed vigor was affected by
sowing density when evaluated by germination speed index and accelerated aging. Seed
physiological quality six month after harvesting was even for all tested cultivars. Storage time and
conditions decreased seed physiological quality for all tested cultivars that don?t conforms with
the seed market standards.