EVALUATING VIABILITY AND VIGOR IN SOYBEAN SEED WITH AUTOMATIC SEED ANALYZER

The relationship between conductivity and standard germination values was investigated to define significance of membrane leakage in adverse weather conditions and to evaluate the conductivity test as a measure of soybean seed quality. The conductivity of seed leachates was measured for individual seeds of three soybean varieties namely: Young, Sharkey and Centennial with the ASAC-1000 Automatic Seed Analyzer. Each variety was harvested at two times (lot A1 and A2). The prediction of germination was based on a 90 muA current flow partition value. Predicted germination values based on conductivity test were close to standard germination in both harvest times. The predicted germination values and standard germination percentage were lower in second harvest than first harvest due to field weathering. Seed population conductivity profiles, constructed from the histogram for the leachate conductivity data, showed the effects of weathering on general seed permeability and there was no major differential response among the three cultivars to weathering. Factors (temperature, humidity, rainfall, seed moisture, mechanical damage and field fungi) other than membrane damage measurable by conductivity test also contribute to weathering injury. Timely harvest of seed fields is essential for obtaining high seed viability and vigour.