The objective of this research was to evaluate the effects of soybean seed vigor on
field plant performance. Nine seed lots of the cv. M-Soy 109 were used. This study utilized
commercially acceptable soybean seed lots (germination greater than 75%) and was conducted in
the agricultural year 1998/1999, in Jaboticabal, São Paulo State, Brazil. In the characterization of
the lots in laboratory, the following tests were used: moisture content, germination in sand, speed
of emergence index, seedling length, seedling dry weight, electrical conductivity and accelerated
ageing. These tests allowed the classification of the nine seed lots in high, medium, and low vigor
lots. With the germination data, the number of seeds sown was calculated for a population of
400,000 plants per hectare, in a spacing of 0.50m between lines. Measurements of some parameters
made during the vegetative and reproductive growth (speed of emergence index, total emergence,
initial and final stand, plant height, amount of plants with flowers in R1, first pod insertion height,
plants survival, yield components and yield) showed that the effects of seed vigor were observed
in early soybean plant establishment (total emergence, emergence speed and stand). There was a
delay in the beginning of the flowering period. The yield (kg.ha-1) was not affected by soybean
seed vigor.