Seedbed Conditions and Prediction of Field Emergence of Soybean Seed

Abstract

It has been difficult to develop consistent relationships between lab measures of soybean [Glycine max (L.) Merr.] seed quality (germination and vigor) and field emergence. Twenty six field emergence experiments (two to four planting dates per year) were conducted over 10 yr to evaluate the effect of seed bed conditions and carryover vs. noncarryover seed on the relationship between standard germination (SG) or accelerated aging germination (AA) and field emergence. Seedbed conditions were characterized by the field emergence index (FEI = mean field emergence/mean SG x 100) calculated for each experiment. The ability of the lab tests to predict field emergence was evaluated by the prediction accuracy (proportion of the seedlots in each test with a specified quality level that had a field emergence above the minimum level). The FEI varied from 108 to 44 and the prediction accuracy varied from 0 to 100%. The prediction accuracy was high for SG and AA for ideal field conditions (FEI ≥ 100) and decreased as soil stress increased. The AA test had higher prediction accuracy than SG in moderate stress. Lowering the minimum acceptable field emergence from 80 to 60% improved the prediction accuracy for SG and AA, but only seedlots with AA ≥ 80% showed acceptable prediction accuracy over a wide range of seedbed conditions. Noncarryover seed had higher prediction accuracy than carryover seed for SG, but there was little difference for AA. High vigor seed (AA ≥ 80%) provided adequate performance in a wide range of seedbed conditions only when the minimum acceptable emergence was lowered to 60%.