Electrical conductivity of soybean seeds after storage in several environments

Membrane integrity, as measured by electrical conductivity (EC), is suggest ed as an indicator of seed vigor in soybean [Glycine max (L.) Merrill] seed s. This study evaluated the effect of storage time and temperature on EC of six soybean seed lots (two lots each of high, medium and low vigor). All s eed lots were adjusted to 120 g kg(-1) seed moisture, sealed in aluminum fo il packets and placed in storage at 10 and 20 degreesC or stored unsealed i n multi-wall paper bags in warehouse (WH) conditions at Lexington, KY, USA for 486 days. Four of the six seed lots were also stored unsealed at 10 deg reesC. All seed lots were sampled at 3-month intervals and evaluated for se ed moisture (SMC), standard germination (SG) and vigor [accelerated aging ( AA) and EC]. After 91 and 204 days in storage, samples initially stored at 20 degreesC and WH were moved to 10 degreesC and sampled at the same interv als. Seed moisture content for unsealed samples equilibrated at 107 g kg(-1 ) (+/-9 g kg(-1)) in both the WH and 10 degreesC environments. No change in SG occurred for seeds stored sealed (120 g kg(-1)) at 10 degreesC, except for the low vigor seed lots which declined significantly at the last sample date. The AA germination declined significantly for all, seed lots stored sealed at 10 degreesC, however the EC did not change during the same storag e period. Seeds stored sealed at 20 degreesC and unsealed in the WH showed rapid declines in AA and SG and significant increases in EC. When these see ds were moved to 10 degreesC, however, the AA continued to decline while th e EC remained at the same level (no significant change) for the remainder o f the seed storage period. Thus whilst the AA declined in all environments, the EC only increased at higher temperatures (20 degreesC, WH) but showed little change during storage at 10 degreesC. Thus, precautions must be take n if using EC to measure soybean seed vigor following storage at 10 degrees C.