SOYBEAN SEED-GERMINATION, VIGOR AND FIELD EMERGENCE

Data from 26 field emergence experiments were used to investigate the relationship between soybean (Glycine max (L.) Merrill) seed germinati on, vigor and field emergence. Each year for 10 years, standard germin ation (SG), accelerated aging (AA) germination and cold test (CT) germ ination were measured on 12 to 52 seed lots of 5 to 21 cultivars and r elated to field emergence in two to four field plantings. A total of 2 72 seed lots were included, of which 146 were carryover seed. Standard germination was generally above 80% but AA and CT varied from >80% to near zero. The field emergence index (FEI = mean field emergence/mean SG x 100), calculated for each field emergence experiment to characte rize seedbed conditions, varied from 108 to 44. The prediction accurac y (proportion of seed lots in each lest with a given critical quality level that had greater than or equal to 80% field emergence) varied fr om 0 to 100%. As the FEI decreased (i.e., seedbed stress increased), p rediction accuracy of all tests decreased. The prediction accuracy) fo r SG with a critical level of 80% was near 100% only when the FEI inde x approached 100. The prediction accuracy for AA at critical levels of 80 or 90% remained near 100% until the FEI approached 80. Increasing the critical level for SG to 95% improved the predictive ability to ne arly equal AA at a critical level of 80%. No test accurately predicted performance when the FEI <80. These data suggest that planting soybea n seed with an AA greater than or equal to 80% or SG greater than or e qual to 95% will ensure adequate performance in many field environment s.