Evaluation location: Missouri, United States
Bioassays were performed in the greenhouse for two SCN populations: Races 1 and 3 (HG Types 2.5.7 and 0, respectively), during 2011-2014. The methods used were described by Arelli et al. (2015. New soybean accessions evaluated for reaction to Heterodera glycines populations. Crop Sci 55:1236-1242). In brief, for each nematode population, seven seedlings were evaluated for each of 239 accessions, susceptible control, and indicator lines. Each seedling within a genotype represented a single replication; the test was completely randomized and repeated twice. Approximately 30 d after inoculation, plant roots were individually washed with a strong jet of water to dislodge white females and cysts. These were counted under a stereomicroscope, and a female index (FI%) was calculated for the number of females developed on each line in each replication. Data were combined for the two tests for each nematode population for ANOVA of female and means separated with Fisher’s LSD based on a significant F test. Ratings of resistant (FI=0-9%), moderately resistant (FI=10-30%), moderately susceptible (FI=31%-60%), and susceptible (FI>60%) used to classify the reaction of the accessions were based on Schmitt and Shannon (1992. Differentiating soybean responses to Heterodera glycines races. Crop Sci 32:275-277)