Development of a simple evaluation method of soybean seedling emergence against soil crust

Soil crust is of high concern in soybean cultivation due to its adverse impact on seedling emergence. Despite the necessity of soybean varieties with stable seedling emergence against soil surface crust, genotypic variation of this trait has not been well understood because there have been no general protocols widely applicable to a set of accessions. The major constraint in conducting such experiments is the difficulty in reproducing soil crust with uniform hardness for each set of experiments. In this study, a simple method that can evaluate the seedling emergence under the conditions of uniform hardness of soil crust using gypsum mixed soil was developed and tested for 82 soybean accessions. Among the tested accessions, five genotypes with high seedling emergence under soil crust conditions were identified.